Mm

Figure 1.31: Continued.

G. Photograph of the ovary of Myxine glutinosa. Nearly mature eggs (E) dangle within individual peritoneal slings (ML) from follicular ligaments (FL) attached to the ovary. Two atretic eggs are shown (DE). The intestine (I) is shown at the top.

Figure 1.32: The epithelium lining hollow, cystovarian ovaries of many teleosts is thrown into a complex series of ovigerous folds.

A. Schematic diagram of a cross section of one of the paired ovaries of the sculpin, Alcichthys alcicornis. (From Koya, Mune-hara, and Takano, 1997; © reproduced with permission of John Wiley & Sons, Inc.).

B. Complex ovigerous folds in the ovary of the surfperch, Cymatogaster. (From Hoar 1969; reproduced with permission from Elsevier Science).

C. Photomicrographs of cross sections of the ovary of the brook stickleback Eucalia inconstans showing ovigerous folds (arrows) extending into the ovocoel (OC). Left X 54; right X 155. (From Braekevelt and McMillan, 1967; © reproduced with permission of John Wiley & Sons, Inc.).

Figure 1.32: The epithelium lining hollow, cystovarian ovaries of many teleosts is thrown into a complex series of ovigerous folds.

A. Schematic diagram of a cross section of one of the paired ovaries of the sculpin, Alcichthys alcicornis. (From Koya, Mune-hara, and Takano, 1997; © reproduced with permission of John Wiley & Sons, Inc.).

B. Complex ovigerous folds in the ovary of the surfperch, Cymatogaster. (From Hoar 1969; reproduced with permission from Elsevier Science).

C. Photomicrographs of cross sections of the ovary of the brook stickleback Eucalia inconstans showing ovigerous folds (arrows) extending into the ovocoel (OC). Left X 54; right X 155. (From Braekevelt and McMillan, 1967; © reproduced with permission of John Wiley & Sons, Inc.).

Figure 1.33: The ovary of teleosts is supplied with blood from several arteries that branch off the dorsal aorta, entering the dorsal side of the ovary through the mesovarium. Each follicle in the ovary of the killifish Fundulus is supplied by a primary arteriole that reaches it through a stalk of stromal elements. (From Brummett, Dumont, and Larkin, 1982; © reproduced with permission of John Wiley & Sons, Inc.).

A. Scanning electron micrograph of a developing follicle. The follicle is anchored in the stroma by a stalklike structure (ST) surrounded by stromal elements. Blood vessels (arrows) can be seen in the apical hemisphere of the follicle. X 80.

B. Electron micrograph of a cross section the stalklike structure. A central arteriole (AR) is surrounded by smooth muscle (SM), a nerve (N), abundant collagen (C), and stromal cells (SC). An epithelioid layer of stromal cells (ES) encloses the structure. X 4,300.

C. The superficially located vessels in the apical or luminal hemisphere of the follicle are more readily apparent and are presumed to be venules that collect blood from the intervening capillary bed and transport it to a vessel that forms a loop (arrows) surrounding the presumed site of future ovulation on the luminal side of the follicle. These vessels terminate in a single collecting vessel that courses toward the outer surface of the ovary. X 250.

Figure 1.33: The ovary of teleosts is supplied with blood from several arteries that branch off the dorsal aorta, entering the dorsal side of the ovary through the mesovarium. Each follicle in the ovary of the killifish Fundulus is supplied by a primary arteriole that reaches it through a stalk of stromal elements. (From Brummett, Dumont, and Larkin, 1982; © reproduced with permission of John Wiley & Sons, Inc.).

A. Scanning electron micrograph of a developing follicle. The follicle is anchored in the stroma by a stalklike structure (ST) surrounded by stromal elements. Blood vessels (arrows) can be seen in the apical hemisphere of the follicle. X 80.

B. Electron micrograph of a cross section the stalklike structure. A central arteriole (AR) is surrounded by smooth muscle (SM), a nerve (N), abundant collagen (C), and stromal cells (SC). An epithelioid layer of stromal cells (ES) encloses the structure. X 4,300.

C. The superficially located vessels in the apical or luminal hemisphere of the follicle are more readily apparent and are presumed to be venules that collect blood from the intervening capillary bed and transport it to a vessel that forms a loop (arrows) surrounding the presumed site of future ovulation on the luminal side of the follicle. These vessels terminate in a single collecting vessel that courses toward the outer surface of the ovary. X 250.

Figure 1.34: Thick bundles of non-myelinated nerves, presumably autonomic, accompany the ovarian artery and vein in the ovary of tilapia Oreochromis niloticus (From Nakamura, Specker, and Nagahama, 1996; reproduced with permission from the Zoological Society of Japan).

A. Photomicrograph of a part of the ovary showing thick nerve bundles (large arrows) near the artery (A) and veins (V). Clusters of steroid-producing cells (small arrows) are seen in the interstitial area. X 360.

B. Electron micrograph of a cross section of a thick nerve bundle in the ovary. The bundle consists of more than 1,000 axons and some neurilemma cells (arrows). X 3,800.

C. Cross section of non-myelinated axons in a nerve bundle.

Abbreviations: CV, dense-cored vesicles; M, mitochondria; MT, microtubules; NF, neurofilaments; SV, synaptic vesicles. X 33,200.

D. Nerve bundle (arrows) is distributed near a cluster of steroid-producing cells (SPC) showing well-developed agranular endoplasmic reticulum and mitochondria with tubular cristae. X 41,600.

Figure 1.34: Thick bundles of non-myelinated nerves, presumably autonomic, accompany the ovarian artery and vein in the ovary of tilapia Oreochromis niloticus (From Nakamura, Specker, and Nagahama, 1996; reproduced with permission from the Zoological Society of Japan).

A. Photomicrograph of a part of the ovary showing thick nerve bundles (large arrows) near the artery (A) and veins (V). Clusters of steroid-producing cells (small arrows) are seen in the interstitial area. X 360.

B. Electron micrograph of a cross section of a thick nerve bundle in the ovary. The bundle consists of more than 1,000 axons and some neurilemma cells (arrows). X 3,800.

C. Cross section of non-myelinated axons in a nerve bundle.

Abbreviations: CV, dense-cored vesicles; M, mitochondria; MT, microtubules; NF, neurofilaments; SV, synaptic vesicles. X 33,200.

D. Nerve bundle (arrows) is distributed near a cluster of steroid-producing cells (SPC) showing well-developed agranular endoplasmic reticulum and mitochondria with tubular cristae. X 41,600.

Figure 1.35: In the killifish Fundulus heteroclitus, the posterior portion of the ovary is a thin-walled nongerminal ovisac that is continuous with the short oviduct and apparently serves as a receptacle for ovulated eggs prior to their release to the external environment. These cells may function in the transport of ovulated eggs or they may secrete ajelly that forms a surface coat for the extruded eggs. (From Brummett, Dumont, and Larkin, 1982; © reproduced with permission of John Wiley & Sons, Inc.).

A. Electron micrograph of the luminal epithelium of this thin-walled region showing a localized population of unusual cells with long apical cytoplasmic extensions bearing short microvilli and extensive basal interdigitations and desmosomes. Lobate nuclei and numerous mitochondria occupy the basal cytoplasm. X 5,400.

B. Uncoated endocytotic pits and hemidesmosomes (arrows) are seen adjacent to the basal lamina of these cells. There are a few microtubules in the cytoplasm. X 28,300.

Figure 1.35: In the killifish Fundulus heteroclitus, the posterior portion of the ovary is a thin-walled nongerminal ovisac that is continuous with the short oviduct and apparently serves as a receptacle for ovulated eggs prior to their release to the external environment. These cells may function in the transport of ovulated eggs or they may secrete ajelly that forms a surface coat for the extruded eggs. (From Brummett, Dumont, and Larkin, 1982; © reproduced with permission of John Wiley & Sons, Inc.).

A. Electron micrograph of the luminal epithelium of this thin-walled region showing a localized population of unusual cells with long apical cytoplasmic extensions bearing short microvilli and extensive basal interdigitations and desmosomes. Lobate nuclei and numerous mitochondria occupy the basal cytoplasm. X 5,400.

B. Uncoated endocytotic pits and hemidesmosomes (arrows) are seen adjacent to the basal lamina of these cells. There are a few microtubules in the cytoplasm. X 28,300.

Figure 1.36: Photomicrographs of sections of the ovary and the epithelium of the ovarian luminal wall the meda-ka Oryzias latipes showing annual cyclic changes. (From Yamamoto, 1963; reproduced with permission from the Zoological Society of Japan).

A. Luminal wall during vitellogenesis (January), (la-c).

B. As the ova mature (February), the luminal wall thickens and its simple cuboidal epithelium becomes simple columnar as secretory activity increases. The underlying tunica albuginea thickens as vascularization increases and smooth muscle develops. (2a-c).

C. The luminal wall continues to thicken (April) and the epithelial cells become taller. (3a-c).

D. Luminal wall in May showing active apocrine secretion. (4a-c).

E. Luminal wall following ovulation (September). (5a-c).

F. After spawning, the epithelium and tunica albuginea undergo involution (November). (6a-c).

G. Rapid changes occur in the luminal wall following spawning. X 440. (7a-c) Immediately after ovulation, the wall becomes thin (left) with a squamous epithelium and reduced tunica submucosa. By the next day, fluid has accumulated in the epithelial cells which once again appear columnar (middle). The vascular subepithelial connective tissue recovers. Two days after spawning (right).

Abbreviations: be, extravasated blood cells; bv, blood vessel; le, epithelium; oe, oedematous tissue; ov, ovarian lumen; ss, secreted substance; vo, vacuole in columnar epithelium.

Magnification offigures A to F: top X110; middle X 440; bottom X1100.

Figure 1.37: Photomicrographs of the simple columnar epithelium of microvillous cells lining the ovarian cavity of the bleak Alburnus alburnus. Around the time of ovulation, these cells bulge apically into the lumen and a few small clusters are also found in the oviduct. (From Lahnsteiner, Weismann, and Patzner, 1997; reproduced with permission from Elsevier Science).

A. General view of the ovary showing the labyrinthine ovarian cavity.

B. In some regions, the theca externa of the follicle surrounds the ovarian cavity, not the epithelium of the ovarian cavity.

C. Cross section of the wall of the oviduct. The arrow indicates a cluster of microvillous cells.

D. Wall of the oviduct showing clusters of microvillous cells.

Abbreviations: ci, cilia; ct, connective tissue; ep, epithelium; fo, theca externa of follicle; lu, lumen of oviduct; oc, ovarian cavity; ov, ovum; p, peritoneum; st, stroma; zp, zona pellucida.

Figure 1.37: Photomicrographs of the simple columnar epithelium of microvillous cells lining the ovarian cavity of the bleak Alburnus alburnus. Around the time of ovulation, these cells bulge apically into the lumen and a few small clusters are also found in the oviduct. (From Lahnsteiner, Weismann, and Patzner, 1997; reproduced with permission from Elsevier Science).

A. General view of the ovary showing the labyrinthine ovarian cavity.

B. In some regions, the theca externa of the follicle surrounds the ovarian cavity, not the epithelium of the ovarian cavity.

C. Cross section of the wall of the oviduct. The arrow indicates a cluster of microvillous cells.

D. Wall of the oviduct showing clusters of microvillous cells.

Abbreviations: ci, cilia; ct, connective tissue; ep, epithelium; fo, theca externa of follicle; lu, lumen of oviduct; oc, ovarian cavity; ov, ovum; p, peritoneum; st, stroma; zp, zona pellucida.

Figure 1.38: Electron micrographs of microvillous cells from the ovarian cavity of Alburnus alburnus. (From Lahnsteiner, Weismann, and Patzner, 1997; reproduced with permission from Elsevier Science).

E. Lipid vacuoles in the cytoplasm.

F. A microvillous cell has released a membrane-bound cytoplasmic bleb; this is apocrine secretion.

Figure 1.38: Electron micrographs of microvillous cells from the ovarian cavity of Alburnus alburnus. (From Lahnsteiner, Weismann, and Patzner, 1997; reproduced with permission from Elsevier Science).

E. Lipid vacuoles in the cytoplasm.

F. A microvillous cell has released a membrane-bound cytoplasmic bleb; this is apocrine secretion.

Figure 1.38: Continued.

A. Protein production is indicated by the prominent nucleolus and abundant tubular granular endoplasmic reticulum that forms concentric layers around the basal nucleus.

B. The presence of lamellar bodies in the microvillous cells results from phagocytosis of débris from the lumen.

C. The cytoplasm of a microvillous cell displays the organelles of protein production: nucleolus, agranular endoplasmic reticulum, and free ribosomes. The inset shows an autophagic vesicle in a region containing secretory vesicles.

D. Golgi complex and neighbouring secretory vesicles.E. Lipid vacuoles in the cytoplasm.

F. A microvillous cell has released a membrane-bound cytoplasmic bleb; this is apocrine secretion.

Abbreviations: ap, cytoplasmic bleb released by apocrine secretion; av, autophagic vesicle; bl, basal lamina; c, coated vesicles; go, Golgi complex; lb, lamellar bodies; li, lipid vacuoles; lu, lumen; mi, mitochondria; nl, nucleolus; nu, nucleus; r, ribosomes; rer, granular endoplasmic reticulum; sv, secretory vesicle.

Abbreviations: ap, cytoplasmic bleb released by apocrine secretion; av, autophagic vesicle; bl, basal lamina; c, coated vesicles;

go, Golgi complex; lb, lamellar bodies; li, lipid vacuoles; lu, lumen; mi, mitochondria; nl, nucleolus; nu, nucleus; r, ribosomes;

rer, granular endoplasmic reticulum; sv, secretory vesicle.

Figure 1.38: Continued.

A. Protein production is indicated by the prominent nucleolus and abundant tubular granular endoplasmic reticulum that forms concentric layers around the basal nucleus.

B. The presence of lamellar bodies in the microvillous cells results from phagocytosis of débris from the lumen.

C. The cytoplasm of a microvillous cell displays the organelles of protein production: nucleolus, agranular endoplasmic reticulum, and free ribosomes. The inset shows an autophagic vesicle in a region containing secretory vesicles.

D. Golgi complex and neighbouring secretory vesicles.E. Lipid vacuoles in the cytoplasm.

F. A microvillous cell has released a membrane-bound cytoplasmic bleb; this is apocrine secretion.

Abbreviations: ap, cytoplasmic bleb released by apocrine secretion; av, autophagic vesicle; bl, basal lamina; c, coated vesicles; go, Golgi complex; lb, lamellar bodies; li, lipid vacuoles; lu, lumen; mi, mitochondria; nl, nucleolus; nu, nucleus; r, ribosomes; rer, granular endoplasmic reticulum; sv, secretory vesicle.

Abbreviations: ap, cytoplasmic bleb released by apocrine secretion; av, autophagic vesicle; bl, basal lamina; c, coated vesicles;

go, Golgi complex; lb, lamellar bodies; li, lipid vacuoles; lu, lumen; mi, mitochondria; nl, nucleolus; nu, nucleus; r, ribosomes;

rer, granular endoplasmic reticulum; sv, secretory vesicle.

Figure 1.39: The ovaries of syngnathids consist of a sheet of follicles, with their supporting vascular stroma, in the form of a tubular scroll extending lengthwise. A. The upper drawing shows the paired ovaries of the pipefish Sygnathus scov-elli which open into the single oviduct. The dashed lines indicate the segment of the ovary that is enlarged below. The middle section has been unfurled to show the follicles and lumen. A single germinal ridge forms the inner margin of the scroll and, extending from this, is a sequential array of follicles arranged according to their developmental age, sandwiched between the outer ovarian wall and the inner luminal epithelium. Mature oocytes are ovulated from the opposite margin of the scroll, the mature edge, into the ovarian lumen. (From Begovac and Wallace, 1987; © reproduced with permission of John Wiley & Sons, Inc.).

In the seahorse Hippocampus erec-tus, there are two germinal ridges that run the length of the tubular ovary on opposite edges of the ovarian sheet. The ovary has been cut along its dorsal midline and both halves have been unrolled. Developing follicles arise from each germinal ridge and grow toward a shared mature region near the middle of the sheet (From Selman, Wallace, and Player, 1991; © reproduced with permission of John Wiley & Sons, Inc.).

Balbiani vitelline

Lipid

HI. Cortical Aiveoii Formation ET. Vitellogenesis 3L Oocyte Maturation 3ZI. Mature Egg j

Lipid

X. Oogonia H. Primary Growth a. Chromatin Nucleolus Phase b. Perinucleolar Phase

Figure 1.40: In contrast to the random organization of ovaries of other fish, the temporal and spatial correlation of oocyte development, as seen in syngnathids, facilitates the study of specific events in follicular development. These sequences may be seen in any cross section of the ovaries. (Figures A, B, and C © reproduced with permission of John Wiley & Sons, Inc.). A. Schematic diagram indicating the sequential stages of oocyte development in an optimal section of the ovary of the pipefish Sygnathus scovelli. Stage designations are indicated by Roman numerals. (From Begovac and Wallace, 1988).

Figure 1.40: Continued.

B. Photomicrograph of a cross section of the ovary of the pipefish. A sequential spiral of developing oocytes is seen, from the earliest stage in the germinal ridge (arrowhead) to the mature edge with the largest oocyte (O) at the dotted line. D, dorsal, L, ovarian lumen; V, ventral. X 100 (From Begovac and Wallace, 1987).

C. Photomicrograph of a cross section through the ovary of the seahorse Hippocampus erectus. The follicular lamina has two germinal ridges (arrowheads) from which developing follicles migrate ventrally. D, dorsal; L, lumen; LE, luminal epithelium; O, oocyte in developing follicle; V, ventral; W, muscular wall of the ovary. X 81. (From Selman, Wallace and Player, 1991).

Figure 1.40: Continued.

B. Photomicrograph of a cross section of the ovary of the pipefish. A sequential spiral of developing oocytes is seen, from the earliest stage in the germinal ridge (arrowhead) to the mature edge with the largest oocyte (O) at the dotted line. D, dorsal, L, ovarian lumen; V, ventral. X 100 (From Begovac and Wallace, 1987).

C. Photomicrograph of a cross section through the ovary of the seahorse Hippocampus erectus. The follicular lamina has two germinal ridges (arrowheads) from which developing follicles migrate ventrally. D, dorsal; L, lumen; LE, luminal epithelium; O, oocyte in developing follicle; V, ventral; W, muscular wall of the ovary. X 81. (From Selman, Wallace and Player, 1991).

Figure 1.41: Syngnathid ovaries are covered on the outside by visceral mesothelium of squamous to low cuboidal cells that is continuous with the mesovarium. It is subtended by variable amounts of collagenous connective tissue connecting it to several layers of smooth muscle. (Figures A, B, and C © reproduced with permission of John Wiley & Sons, Inc.).

A. Seahorse, Hippocampus erectus. Electron micrograph of a section through a typical mesothelial cell showing its irregular apical surface as well as numerous pits and vesicles (arrowheads) on both their apical and basal surfaces. These cells contain abundant cytoplasmic filaments (arrow). X 20,390 (From Selman, Wallace, and Player, 1991).

B. Seahorse, Hippocampus erectus. Photomicrograph of a section through the junction of the mesovarium (M) with the ovarian wall (W). The ovary is covered by visceral peritoneum (arrowheads) which is continuous with the epithelium of

the mesovarium. Blood vessels are abundant within the mesovarium and within the outer layers of the ovarian wall. L, ovarian lumen; O, oocyte. X 140 (From Selman, Wallace, and Player, 1991).

C. Electron micrograph of a section through the ovarian wall of the pipefish, Syngnathus scovelli. The simple squamous coe-lomic epithelium (CE) of the outer ovarian wall faces the peritoneal cavity (PC). It overlies several layers of smooth muscle (SM) which comprise most of the thickness of the ovarian wall; the fibres are arranged roughly into two layers: an inner circular and an outer longitudinal. Small blood vessels course between the muscle cells as well as bundles of unmyelinated nerves (N) that tend to run parallel to the long axis of the ovary. Vascular connective tissue of variable thickness occurs within the wall; a connective tissue cell is shown (*). X 7,980 (From Begovac and Wallace, 1987).

Figure 1.42: The germinal ridges extend the length of the syngnathid ovary and contain the proliferative stem cells from which the oocytes are derived and follicles formed. Photomicrographs of sections through the ovary of the seahorse Hippocampus erectus. (From Selman, Wallace, and Player, 1991; © reproduced with permission of John Wiley & Sons, Inc.).

A. Two germinal ridges (arrowheads) project into the ovarian lumen (L). The ridges are covered by the luminal epithelium of squamous to cuboidal cells and contain richly vascular connective tissue surrounding each follicle. The germinal ridges and the follicles arising from each form scrolls that twist in opposite directions. O, oocyte. X 75.

B. Extensive lymphatic spaces (*), lined by attenuated endothelial cells, penetrate the stroma of the ovary. Left: a lymphatic vessel lying between adjacent follicles and the overlying luminal epithelium (LE). Right: a lymphatic vessel occupies much of the space between adjacent follicles and the ovarian wall (W). V, small vein. X 565.

Figure 1.42: The germinal ridges extend the length of the syngnathid ovary and contain the proliferative stem cells from which the oocytes are derived and follicles formed. Photomicrographs of sections through the ovary of the seahorse Hippocampus erectus. (From Selman, Wallace, and Player, 1991; © reproduced with permission of John Wiley & Sons, Inc.).

A. Two germinal ridges (arrowheads) project into the ovarian lumen (L). The ridges are covered by the luminal epithelium of squamous to cuboidal cells and contain richly vascular connective tissue surrounding each follicle. The germinal ridges and the follicles arising from each form scrolls that twist in opposite directions. O, oocyte. X 75.

B. Extensive lymphatic spaces (*), lined by attenuated endothelial cells, penetrate the stroma of the ovary. Left: a lymphatic vessel lying between adjacent follicles and the overlying luminal epithelium (LE). Right: a lymphatic vessel occupies much of the space between adjacent follicles and the ovarian wall (W). V, small vein. X 565.

Figure 1.43: As in many bony fishes, the lumen of the cystovarian ovaries of syngnathids is lined by an epithelium that is derived from the coelomic mesothelium and is continuous with the oviduct. The epithelial cells lie on a distinct basal lamina and vary in shape from squamous over the germinal ridge to cuboidal or columnar over more mature follicles. These electron micrographs show the luminal epithelium from three regions of the ovary of the seahorse Hippocampus erectus. Single arrows indicate tightjunctions, double arrows, desmosomes. (From Selman, Wallace, and Player, 1991; © reproduced with permission of John Wiley & Sons, Inc.).

A. Luminal epithelial cells over the germinal ridge are relatively flat and are highly interdigitated on their lateral surfaces. The basal plasmalemma is elaborately infolded. Arrowheads indicate the distinct basal lamina. X 8,170.

B. Cuboidal luminal epithelial cells overlie small follicles. The basal lamina (arrowheads) of the luminal epithelial cells lies next to the thick basal lamina (*) of follicular cells (F) from the underlying follicle. X 7,520.

C. Columnar epithelial cells overlying large follicles display long microvilli, interdigitating lateral membranes, and numerous cytoplasmic filaments. X 6,720. Detail of the cytoplasmic filaments is shown in the inset. X 23,800.

Figure 1.44: Electron micrograph of a luminal epithelial cell from the ovary of the pipefish Syngnathus scovelli showing blebbing into the ovarian lumen (L). These cells are highly secretory. Intracellular filaments (F) are abundant. Well developed tightjunctions are seen on each side of the bleb. X 9,760 (From Begovac and Wallace, 1987; © reproduced with permission of John Wiley & Sons, Inc.).

Figure 1.45: A form of apocrine secretion has been described in the columnar epithelial cells of the ovarian lumen of tele-

osts.

A. Electron micrograph of the ovarian wall of the medaka Oryzias latipes following ovulation. Apical "blebs" break off from the rest of the cell and contribute to the secreted material in the lumen. X 3,700 (From Takano, 1968; reproduced with permission of the Graduate School of Fisheries Sciences, Hokkaido University).

Abbreviations: L, ovarian lumen; LS, liquid within intercellular spaces; N, nucleus; SM, smooth muscle of subepithelial layer.

B. Electron micrograph of the maturing ovary of the goldfish Carassius auratus. The columnar epithelial cells lining the lumen (OL) develop cilia (Ci); large cytoplasmic blebs (Ap) break away from the surface at the bases of the cilia. X 5,700 (From Takahashi and Takano, 1971; reproduced with permission from the Zoological Society of Japan).

Abbreviations: M, mitochondrion; N, nucleus.

ovarian wall blood vessel ovarian cavily duncle ovarian follicle blood vessel ovarian stroma

Figure 1.46: The lining of the hollow ovary in some species of Scorpaeniformes secretes a bilobed, gelatinous mass that provides protection for the eggs. The paired cystovarian ovaries are sheathed within a wall of smooth muscle and connective tissue and are enclosed by visceral peritoneum. Anteriorly the ovaries are rounded and each of them is suspended by a spongy, vessel-rich hilus whose vessels penetrate into the lumen to enter the spongy, vascular, ovigerous stroma. Suspended by the hilus at the anterior end of each lobe, the ovigerous stroma floats free within the lumen.

A. Schematic diagram of the ovary of the rockfish Sebastolobus macrochir. (From Koya and Matsubara, 1995; reproduced with permission of the Graduate School ofFisheries Sciences, Hokkaido University).

B. Diagram of a cross section of the ovary of Dendrochirus brachypterus during reproduction. The ovigerous tissue is covered by an oocyte-producing epithelium that bristles with vascularized "peduncles" that radiate from the stroma;. These peduncles are extensions of the stroma and accommodate secondary oocyte development. (From Fishelson, 1977; reproduced with permission of the author).

Abbreviations: BV, blood vessel; EE, egg envelope; EL, epithelial layer; GL, germinative layer; ML, muscle layer; OL, ovarian lumen; SP, secretory processes.

C. Photomicrograph of oocyte and peduncle from the ovary of Sebastolobus alascanus collected during an early phase of production of gelatinous material. Scale bar = 104 |im. (From Erickson and Pikitch, 1993; reproduced with kind permission of Kluwer Academic Publishers).

Abbreviations: bv, blood vessel; gm, gelatinous material; po, previtellogenic oocyte.

D. Photomicrograph of an ovarian follicle of Sebastolobus macrochir in maturation phase. It projects by a narrow peduncle (p) from the ovarian stroma (s). o, oocyte. Scale bar = 100 pm. (From Koya and Matsubara, 1995; reproduced with permission of the Graduate School ofFisheries Sciences, Hokkaido University).

E. Electron micrograph of a portion of an ovarian follicle of Sebastolobus macrochir in maturation phase. The oocyte (o) is enclosed by the amorphous zona pellucida (ve), a layer of follicular cells (g), theca (t), and the simple squamous luminal epithelium (fe). Scale bar = 5 |im. (From Koya and Matsubara, 1995; reproduced with permission of the Graduate School of Fisheries Sciences, Hokkaido University).

Figure 1.47: Electron micrographs of the epithelia of the ovary of the rockfish Sebastolobus macrochir. The luminal wall is lined by a simple columnar epithelium (A,B) while a more delicate simple columnar epithelium covers the ovigerous tissue (C). (From Koya and Matsubara, 1995; reproduced with permission of the Graduate School of Fisheries Sciences, Hokkaido University).

A. Before ovulation, there is a buildup of the cellular mechanism for protein production in the epithelial cells lining the ovarian wall. These cells produce the outer fibrous layer of the gelatinous mass.

Figure 1.47: Electron micrographs of the epithelia of the ovary of the rockfish Sebastolobus macrochir. The luminal wall is lined by a simple columnar epithelium (A,B) while a more delicate simple columnar epithelium covers the ovigerous tissue (C). (From Koya and Matsubara, 1995; reproduced with permission of the Graduate School of Fisheries Sciences, Hokkaido University).

A. Before ovulation, there is a buildup of the cellular mechanism for protein production in the epithelial cells lining the ovarian wall. These cells produce the outer fibrous layer of the gelatinous mass.

Figure 1.47: Continued.

i: Each epithelial cell bears a large apical projection containing masses of electron-lucent material in the cytoplasm (ap). Bar = 10 |jm.

ii: These electron-lucent masses (*) are surrounded by well-developed agranular endoplasmic reticulum (sER). Bar = 1 pm. iii: The central part of an epithelial cell contains abundant agranular endoplasmic reticulum (sER) and sparse granular endoplasmic reticulum (rER). g, glycogen; m, mitochondria; n, nucleus. Bar = 1 |im. iv: Numerous glycogen granules (g) are seen in the cytoplasm of the basal part of an epithelial cell, bm, basal lamina. Bar = 1 |im.

B. The apical projections (ap) of the epithelial cells of the luminal wall have decreased in height after the first ovulation, mv, microvilli; n, nucleus. Bar = 5 |im. Inset: the apical cytoplasm contains well-developed agranular endoplasmic reticulum (sER). m, mitochondrion. Bar = 1 pm.

C. The more delicate columnar epithelial cells of the ovigeorous lamella secrete the homogeneous inner layer of the gelatinous mass.

i: These cells lie on a basement lamina (bm) that separates them from the cells of the theca (t). m, mitochondria; n, nucleus;

rER, granular endoplasmic reticulum. Bar = 5 |im. ii: The perinuclear cytoplasm shows well developed agranular endoplasmic reticulum (sER), granular endoplasmic reticulum (rER), and a Golgi complex (G). n, nucleus. Bar = 0.1 |im. Inset: The apical cytoplasm showing an exocytotic pit (arrow). Bar = 0.1 |im.

Figure 1.48: Schematic diagram of the formation of gelatinous egg masses in the rockfsh Sebastolobus macrochir. (From

Koya, Hamatsu, and Matsubara, 1995; reproduced with permission from Blackwell Publishing Asia Pty. Ltd.).

A. Anteriorly the ovaries are rounded and each of them is suspended by a spongy, vessel-rich hilus whose vessels penetrate into the lumen to enter the spongy, vascular, ovigerous stroma which floats free within the lumen. The ovigerous tissue is covered by an oocyte-producing epithelium that bristles with vascularized "peduncles" that radiate from the stroma and bear developing oocytes. During the spawning season, epithelia lining he luminal wall and covering the ovigerous tissue secrete a gelatinous mass that fills the lumen and embeds the oocytes and their stalks. Peduncle length increases as vitel-logenesis proceeds.

B. Within the base of each peduncle are previtellogenic oocytes; when a mature oocyte is released at ovulation, a previtello-genic oocyte moves up inside the peduncle to take its place and undergo vitellogenesis.

C. During spawning, the oocytes, embedded in the gelatinous mass, are swept from the lumen. The gelatinous mass, secreted by the epithelia of the two lobes, is extruded around the ovigerous tissue ofboth lobes.

D. The hollow, bilobed egg mass is extruded.

Figure 1.48: Schematic diagram of the formation of gelatinous egg masses in the rockfsh Sebastolobus macrochir. (From

Koya, Hamatsu, and Matsubara, 1995; reproduced with permission from Blackwell Publishing Asia Pty. Ltd.).

A. Anteriorly the ovaries are rounded and each of them is suspended by a spongy, vessel-rich hilus whose vessels penetrate into the lumen to enter the spongy, vascular, ovigerous stroma which floats free within the lumen. The ovigerous tissue is covered by an oocyte-producing epithelium that bristles with vascularized "peduncles" that radiate from the stroma and bear developing oocytes. During the spawning season, epithelia lining he luminal wall and covering the ovigerous tissue secrete a gelatinous mass that fills the lumen and embeds the oocytes and their stalks. Peduncle length increases as vitel-logenesis proceeds.

B. Within the base of each peduncle are previtellogenic oocytes; when a mature oocyte is released at ovulation, a previtello-genic oocyte moves up inside the peduncle to take its place and undergo vitellogenesis.

C. During spawning, the oocytes, embedded in the gelatinous mass, are swept from the lumen. The gelatinous mass, secreted by the epithelia of the two lobes, is extruded around the ovigerous tissue ofboth lobes.

D. The hollow, bilobed egg mass is extruded.

Figure 1.49: Several marine cottid species (Scorpaeniformes) have a unique reproductive mode called "internal gametic association" where spermatozoa are introduced into the ovarian cavity by copulation and float freely in the ovarian fluid although fertilization does not occur until the eggs have been spawned into sea water. These electron micrographs are from the ovary of the marine sculpin Alcichthys alcicornis. (From Koya, Takano, and Takahashi, 1995; Koya, Munehara, and Takano, 1997; © reproduced with permission of John Wiley & Sons, Inc.).

A. The epithelium of the ovigerous lamella during the recovery period following spawning.

Upper. The epithelium is stratified during early recovery. X 6,300.

Lower. Later during the recovery period, a simple layer of epithelial cells is arranged on the basal lamina (bm). X 16,000.

B. The epithelium of the ovarian wall early in the recovery period is ciliated (c).

Upper. The epithelium is simple during early recovery. There are few short apical microvilli. The arrow indicates small apical pits on the epithelial cells. X 6,300.

Inset. These pits are shown in greater detail. The vesicles appear to be discharging their contents into the ovarian lumen.

Lower. Microvilli are well developed on the apical surface of the epithelial cells later in the recovery period. The cytoplasm is packed with well-developed granular endoplasmic reticulum (er). X 7,800.

C. Epithelium from the ovigerous lamella during the spawning period. The epithelial cells manifest the appearance of protein production with abundant basal granular endoplasmic reticulum and active apical Golgi complexes. Numerous pinocytotic pits and vesicles are seen in the peripheral cytoplasm of these cells; increasing numbers of pits and vesicles are also present in the endothelial cells of adjacent capillary walls at this time indicating that active transcytosis is taking place.

Upper. Abundant microvilli extend from the apical surface. Granular endoplasmic reticulum (er) and Golgi complexes (G) are well developed. Note the apical desmosomes between adjacent epithelial cells. X 5,800.

Midleft: Granular endoplasmic reticulum near the nucleus (n) appears to be forming a bud-like extension (arrow). X 13,600.

Mid right: Well developed Golgi complex in the apical cytoplasm. Electron-lucent vesicles (arrow) and slightly electron-dense vesicles (arrowheads) lie near the Golgi lamellae. X 22,200.

Lower left: Vesicles in the apical cytoplasm appear to fuse to form secretory vesicles (arrowheads). The contents of these vesicles are released by exocytosis (arrows). X 18,300.

Lower right: Blebbing of the tips of microvilli (arrow). Some vesicular bodies (arrowhead) lie free in the ovarian lumen (OC).X 11,000.

D. Epithelium from the ovigerous lamella during the spawning period.

Upper left: A pinocytotic pit opens into the intercellular space. X 27,300.

Upper right: Numerous pinocytotic pits (arrows) and vesicles are seen in the basal cytoplasm. X 26,000.

Lower: A strong reaction is seen in the connective tissue (ct) and basal intercellular spaces of fish treated with horseradish peroxidase. Reaction products are also observed in the pits (arrows) and vesicles (arrowheads) near the outer surfaces of the cells. X 24,800.

Figure 1.49: Continued.

E. Epithelium from the ovarian wall during spawning.

Left: Numerous microvilli bristle from the apical surface of the epithelial cells; the cytoplasm contains well devel oped granular endoplasmic reticulum (er) and Golgi complexes (g). X 11,400. Upper right: The apical surface of the epithelial cells is riddled with exocytotic pits (arrow) and vesicles (arrowheads). X 26,700.

Lower right: Apical blebs (arrows) separate from the surface of the epithelial cells to form a microapocrine secretion. X28,900.

F. During spawning, numerous vesicles pack the cytoplasm of endothelial cells (E) from the capillaries of the ovigerous lamellae. Pits open on both the apical and basal surfaces of the endothelial cells (arrows). The capillary lumen (L) is at the left. X 20,000.

G. Adjacent epithelial cells arejoined byjunctional complexes and it is suggested that these tightjunctions isolate the spermatozoa in the lumen from the maternal immune system.

Upper left; right: The apical borders of epithelial cells of an ovigerous lamella arejoined by ajunctional complex (arrow)

and desmosome (d). X 40,000. Lower left: Junctional complex (arrow) and desmosome (d) securing the apical borders of epithelial cells from the ovarian wall. X 40,000.

Figure 1.49: Continued.

H. After the spawning period, the junctions break down and residual spermatozoa are eliminated by invading maternal leucocytes.

Upper left: Plasma cell showing characteristic well-developed granular endoplasmic reticulum (er). X 10,000. Upper right: Polymorphonuclear leucocyte showing lobed nucleus and electron-dense cytoplasmic granules. X 5,000. Mid left: Monocyte, with few cytoplasmic organelles. The arrow indicates a cytoplasmic extension. X 12,000. Lower left: The cytoplasm of a macrophage gives evidence of clean-up of cellular breakdown: membranous whorls, multilamellar bodies (arrow), and a heterogeneous collection of vesicles. X 20,000. Lower right: Masses of macrophages containing lamellar bodies (lm) and electron-dense granules (g) appear during the recovery period. X 3,000.

Figure 1.49: Continued.

H. After the spawning period, the junctions break down and residual spermatozoa are eliminated by invading maternal leucocytes.

Upper left: Plasma cell showing characteristic well-developed granular endoplasmic reticulum (er). X 10,000. Upper right: Polymorphonuclear leucocyte showing lobed nucleus and electron-dense cytoplasmic granules. X 5,000. Mid left: Monocyte, with few cytoplasmic organelles. The arrow indicates a cytoplasmic extension. X 12,000. Lower left: The cytoplasm of a macrophage gives evidence of clean-up of cellular breakdown: membranous whorls, multilamellar bodies (arrow), and a heterogeneous collection of vesicles. X 20,000. Lower right: Masses of macrophages containing lamellar bodies (lm) and electron-dense granules (g) appear during the recovery period. X 3,000.

Figure 1.49: Continued.

I. This diagram summarizes the changes that take place during the reproductive cycle of the sculpin Alcichthys alcicornis. Abbreviations: bm, basal lamina; c, cilium; ct, connective tissue; d, desmosome; DE, degenerating epithelial cell; G,g, Golgi complex; lm, lamellar bodies; n, nucleus; O, oogonium; OC, ovarian cavity.

Figure 1.50: Photomicrographs of cross sections of the ovary of Scyliorhinus canicula. The ovaries of Chondrichthyes are surrounded by the gonadal epithelium and consist of a connective tissue stroma containing developing follicles, postovulatory follicles (corpora lutea), and degenerating follicles (corpora atretica). Blood vessels and nerves course through the stroma. The stroma also contains lymph spaces or membranous folds that are filled with developing blood cells. (From Dodd and Sumpter, 1984; reproduced with permission of Churchill Livingstone)).

Upper: Oocytes in three stages of development: Ol, prior to follicle formation; 02, previtellogenic follicle; and

03, a follicle in early vitellogenesis. Middle: Cross section of early vitellogenic follicle.

Lower: Cross section of a follicle during early atresia. Dissolution of yolk occurs in patches (YD). Abbreviations: BM, basement membrane; BV, blood vessel between theca interna and follicular basement membrane; G, follicular epithelium; TE, theca externa; TI, theca interna; YP, yolk platelets; ZR, zona pellucida.

Figure 1.50: Photomicrographs of cross sections of the ovary of Scyliorhinus canicula. The ovaries of Chondrichthyes are surrounded by the gonadal epithelium and consist of a connective tissue stroma containing developing follicles, postovulatory follicles (corpora lutea), and degenerating follicles (corpora atretica). Blood vessels and nerves course through the stroma. The stroma also contains lymph spaces or membranous folds that are filled with developing blood cells. (From Dodd and Sumpter, 1984; reproduced with permission of Churchill Livingstone)).

Upper: Oocytes in three stages of development: Ol, prior to follicle formation; 02, previtellogenic follicle; and

03, a follicle in early vitellogenesis. Middle: Cross section of early vitellogenic follicle.

Lower: Cross section of a follicle during early atresia. Dissolution of yolk occurs in patches (YD). Abbreviations: BM, basement membrane; BV, blood vessel between theca interna and follicular basement membrane; G, follicular epithelium; TE, theca externa; TI, theca interna; YP, yolk platelets; ZR, zona pellucida.

Figure 1.51: Photomicrograph of the spent ovary of the dogfish shark Squalus acanthias. An unovulated follicle is seen at the lower left. Abundant haemopoietic activity in seen in the loose connective tissue of the stroma. X 50.

Figure 1.52: General view of the reproductive tract of the basking shark Cetorhinus maximus. Left: from the ventral surface; the oviduct on the right is opened longitudinally. Right: lateral view from the right side. Only the right ovary persists and the epigonal organ lies posterior and slightly dorsal to the ovary, being suspended from the dorsal abdominal wall by a backward extension of the mesovarium. The left epigonal organ is of similar size and shape as the right but no ovary is fused to its anterior end and it is suspended by its own peritoneal fold in the corresponding position on the left side of the body cavity. (From Matthews, 1950; reproduced with permission from the Royal Society).

Abbreviations: AP, abdominal pores; CI, cloaca; E, epigonal organ; IN, unpaired oviduct; IS, isthmus; K, kidney; MM, mesome-trium; O, ovary; OA, ostium; OD, paired oviduct; OE, oesophagus; PO, pocket in right side of ovary; R, rectum; SG, oviductal gland; U, uterus; UP, urinary papilla; UR, uterus lined with folds; UT, uterus lined with trophonemata; VC, common vagina; VP, paired vagina of the left side.

FEMALE GENITAL SYSTEMS OF FISH 65

Was this article helpful?

0 0

Post a comment