Seasonal histological changes in the gonads of Sebastodes paucispinis ayres,an ovoviviparous teleost (family scorpaenidae)

The elongate paired testes of Sebastodes paucispinis consist of tubules which radiate from a single longitudinal sperm duct and terminate blindly at the periphery of the testis. They are lined by an epithelium consisting of columnar cells with distinct elliptical nuclei. During fall and winter, germ cells migrate inward from the fibrous capsule of the testis and become lodged among the tubule-boundary cells of the seminiferous tubules where they mature into primary spermatogonia. Each of these undergoes several mitotic divisions to produce large cysts of secondary spermatogonia. Subsequent spermatogenic divisions within these cysts produce large sperm-filled cysts which rupture, releasing the spermatozoa into the lumina of the seminiferous tubules. Seasonal cycles of cholesterol and carbohydrate production by the tubule-boundary cells suggest that they perform the same functions as the Leydig cells (androgen production) and Sertoli cells (nutrition) of other vertebrates. The paired fusiform ovaries consist of spongy tissue surrounded by thin-walled muscular ovisacs that converge posteriorly to form a genital duct. The spongy tissue is arranged in transverse lamellae composed of fibrovascular trunks which support epithelial and ovigerous tissue. A series of oocytes (up to 150 μ in diameter) is produced continually from oogonial nests distributed throughout each lamella. Vitellogenesis begins in July and continues throughout the summer. The follicle surrounding the mature oocyte consists of a bilaminar striated vitelline membrane, two epithelial layers (granulosa and theca), and a profuse capillary network. Spermatozoa appear within the ovaries from October to March. Ovulation probably precedes fertilization since spermatozoa were never found within pre-ovulatory or post-ovulatory follicles. The follicular epithelium regresses after ovulation but the capillary beds remain intact, thus providing a mechanism for fetal-maternal exchange of gases and nitrogenous wastes.     

Localization of vascular endothelial growth factor in the zona pellucida of developing ovarian follicles in the rat: a possible role in destiny of follicles

There is increasing evidence that in many species angiogenic factors, such as vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF), may have important roles in folliculogenesis. The aim of this study is to determine the localization of VEGF and its receptors, Flt-1 and KDR, and bFGF expression in the rat ovary and to evaluate their distributions throughout the different follicular stages. Out of 20 virginal female rats, 10 were studied during the natural ovarian cycle without any ovulation induction. The other 10 were superovulated and their ovaries were studied by western analysis and immunohistochemistry. Granulosa cells (GC) and oocytes of primordial follicles were negative for VEGF. In early primary follicles, VEGF was present in the oocyte but its immunoreactivity was weak, while newly developing zona pellucida (ZP) of primary follicles was negative for VEGF. Subsequently, with the commencement of antral spaces between GC of the secondary follicle, ZP of some secondary follicles became strongly positive for VEGF, forming a continuous ring around the oocyte. In preovulatory mature follicles granulosa and theca interna (TI) cells showed a weak immunoreactivity for VEGF. Western blot analyses have also demonstrated that VEGF, a 26-kDa protein, was present in follicles. Moreover, in ovulated cumulus–oocyte complex we observed a halo-like immunoreactivity of VEGF around the fully mature oocyte. The immunoreactivity for Flt-1 and KDR receptors in growing follicles was mostly limited to GC and TI cells. Anti-bFGF did not exhibit any immunoreactivity in ZP of follicles at any stage. Its expression was weak in GC of the follicles at different stages, whereas, it could be localized to some extent in the blood capillaries of TI of antral follicles and in blood vessels localized in the stroma. Interestingly, VEGF immunoreactivity in the ZP of some secondary follicles is very striking. Accordingly, the possibility that VEGF may be an important regulatory molecule for the dominant follicle selection or atresia should be considered.     

Cyclic changes in the testis of the brook stickleback Eucalia inconstans (Kirtland)

The cyclic changes in the testis of the five-spined stickleback Eucalia inconstans (Kirtland) were studied histologically. Specimens were trapped between July 1965 and July 1967 in a shallow pond near London, Ontario. A three-dimensional microscopic study showed a main vas deferens and a system of primary, secondary and tertiary tubules. The testis cycle was divided into seven arbitrary stages. Spawning takes place from mid-April to mid-July. This is followed by the division of primary spermatogonia which are located along the walls of the tubules, producing cysts of spermatogonia enclosed in connective tissue which is surrounded by a thin epithelium. Both primary and secondary spermatocytes develop within these cysts. Breakdown of the cysts occurs with the development of spermatids and spermiogenesis occurs while spermatids are free in the tubules. Over-wintering of mature sperm takes place. Development of mature sperm from primary spermatogonia takes about 156 days. Germinal epithelium is absent but primary germ cells are believed to be those cells occupying the spaces between the tubules of the testis. No tissue which might be implicated in hormone production was observed. Phagocytic invasion of the testis has been studied. Massive infiltration by phagocytes is believed to be responsible for the sudden increase in testis weight observed during spawning. These cells ingest sperm nuclei and groups of them have been observed in the lumen of the tubules and the vas deferens, probably on their way out of the body.     

Ovarian structure and mode of egg production in the seaweed pipefish Syngnathus schlegeli (Syngnathidae)

This study investigated ovarian structure and mode of egg production in the seaweed pipefish, Syngnathus schlegeli. The ovary had a rolled sheet-like structure where developing follicles were arranged serially in sequence according to their development, with a single germinal ridge running along the edge of the sheet. Oocytes of various developmental stages were concomitantly present in the ovary, and the number of mature eggs increased continuously over time, indicating that egg production is asynchronous. This would be a physiological basis for multiple spawning within a short time span associated with polygamy in this fish.     

Classification of small type B/C follicles as primordial follicles in mature rats

In the present study, follicles were classified according to the morphology of their granulosa cells. Type B follicles contained only flattened granulosa cells; type B/C follicles had a mixture of flattened and cuboidal granulosa cells in a single layer, and type C follicles had a single layer of cuboidal granulosa cells. The primary objectives of the study were to determine whether 5-bromo-2-deoxyuridine incorporation into type B/C follicles was a marker for initiation of growth and how long type B/C follicles could remain at the same stage before transformation to type C follicles. Female Holtzman rats received bromo-deoxyuridine for 7 days. After the infusion (day minipumps were removed = day 0), rats were ovariectomized on days 0 (n = 9), 30 (n = 8), 90 (n = 8) and 150 (n = 9). The numbers of type B, B/C and C follicles within one ovary were determined using modified fractionator counting. Analysis over all times demonstrated that there were more (P < 0.0001) type B/C (941 +/- 61 per ovary) than type C (140 +/- 18 per ovary) or type B (159 +/- 19 per ovary) follicles. The numbers of type B and type C follicles did not differ from each other at any time. Only one of 34 rats evaluated had bromo-deoxyuridine-labelled type B follicles. On day 150, 57% of the bromo-deoxyuridine-labelled type B/C follicles remained from day 0. It is concluded that (1) DNA synthesis in granulosa cells of type B/C follicles is not a reliable indicator of impending growth; and (2) type B and type B/C follicles are both components of the pool of primordial follicles.     

Oviductal sperm storage structure and their changes during the seasonal (dissociated) reproductive cycle in the soft-shelled turtle Lissemys punctata punctata

The oviduct of the Indian fresh water soft-shelled turtle Lissemys punctata punctata was examined throughout the year under light and scanning electron microscopes to determine the location, histomorphological characteristics, and function of sperm storage structure, as well as their changes at different phases of the seasonal reproductive cycle. Sperm storage structures in the form of tubules were observed in the wall of isthmus throughout the year. These tubules developed either by folding or fusion of the oviductal mucosal folds and were lined by both ciliated and nonciliated epithelial cells. The height and secretory activities of the epithelia were markedly high during the breeding phase (August to September) but low in the nonbreeding phase (October to June). A few short tubules lined by cuboidal epithelium appear in the wall of infundibulum only during the breeding phase. Following mating (May), inseminated sperm were stored within the tubules of isthmus up to the pre-ovulatory stage (August). Thereafter, sperm associated with PAS-positive materials secreted from the epithelium (referred to as a carrier matrix) moved forward to the infundibulum and were stored within the storage tubules of the infundibulum for a short time. Subsequently, sperm evacuated the storage tubules and entered the oviductal lumen to fertilize the subsequently ovulated eggs during or prior to ovulation. The isthmus-tubules become shorter and narrower in the regressive phase (October to November) and remained so until the early preparatory phase (April). Sperm release might have been stimulated by estrogen secreted from the ovarian follicles of pre-ovulatory turtles. Stored sperm not utilized for fertilization remained viable not less than six months in the present turtle species.     

Ultrastructure of Pharyngostomoides procyonis Harkema 1942 (Diplostomatidae). II. The female reproductive system

Several components of the female reproductive system of Pharyngostomoides procyonis, including the vitellaria and vitelline duct, ovary and oviduct, Laurer's canal, and Mehlis' gland and associated ducts, were observed with the electron microscope. Vitelline follicles contain cells in various stages of development. Mature vitelline cells contain membrane-delimited clusters of vitelline globules near the plasma membrane. Cilia are present in the vitelline duct. The ovary contains germ cells in various stages of maturation. Oogonia are found in the peripheral region. Mature oocytes contain numerous dense bodies near the plasmalemma. Also included in the cytoplasm of mature oocytes are "nucleolus-like bodies," myelin-like bodies, and mitochondria containing dense granules and few cristae. The epithelium of the oviduct is ciliated. Sperm are present in the oviduct and in Laurer's canal. Two types of secretory cells found in Mehlis' gland are described.     

Ovarian structure and oogenesis of the extremophile viviparous teleost Poecilia mexicana (Poeciliidae) from an active sulfur spring cave in Southern Mexico

The structure of the ovary and oogenesis of Poecilia mexicana from an active sulfur spring cave is documented. Poecilia mexicana is the only poeciliid adapted to a subterranean environment with high hydrogen sulfide levels and extreme hypoxic conditions. Twenty females were captured throughout one year at Cueva del Azufre, located in the State of Tabasco in Southern Mexico. Ovaries were processed with histological techniques. P. mexicana has a single, ovoid ovary with ovigerous lamella that project to the ovarian lumen. The ovarian wall presents abundant loose connective tissue, numerous melanomacrophage centers and large blood vessels, possibly associated with hypoxic conditions. The germinal epithelium bordering the ovarian lumen contains somatic and germ cells forming cell nests projecting into the stroma. P. mexicana stores sperm in ovarian folds associated with follicles at different developmental phases. Oogenesis in P. mexicana consisted of the following stages: (i) oogonial proliferation, (ii) chromatin nucleolus, (iii) primary growth, subdivided into: (a) one nucleolus, (b) multiple nucleoli, (c) droplet oils‐cortical alveoli steps; (iv) secondary growth, subdivided in: (a) early secondary growth, (b) late secondary growth, and (c) full grown. Follicular atresia was present in all stages of follicular development; it was characterized by oocyte degeneration, where follicle cells hypertrophy and differentiate in phagocytes. The ovary and oogenesis are similar to these seen in other poeciliids, but we found frequent atretic follicles, melanomacrophage centers, reduced fecundity and increased of offspring size.     

Immunohistochemical study of the C-cell complex of dog thyroid glands with reference to the reactions of calcitonin,C-thyroglobulin and 19S thyroglobulin

Summary Continued from the previous study in fetal animals (Kameda et al. 1980), the development and maturation of C-cell complexes in postnatal dogs from newborn to adult were investigated by use of an immunoperoxidase method using antisera to calcitonin, C-thyroglobulin (C-Tg) and 19S thyroglobulin, respectively. The younger the animals were, the more numerous were undifferentiated cells and high columnar epithelial cells in the complexes. With increasing age, the constituent elements of the complexes progressively differentiated. In one type of complex there are a large number of C-cells in various developmental stages, as well as undifferentiated cells and cysts. C-cell complexes composed mostly of mature C-cells were regarded as the more highly differentiated structures of this type. A second type contains follicular cells in various stages of differentiation in addition to undifferentiated cells and C-cells, i.e., 19S-positive cell masses not yet organized into follicles, primordial follicles with small lacunae and comparatively larger follicles. The follicular cells in the complexes were similar with respect to immunoreaction and folliculogenesis to the cells of fetal thyroids, but they developed very slowly. In conclusion, the present study indicates that follicular thyroid cells can differentiate within C-cell complexes, i.e., they develop from cells of ultimobranchial body origin.     

Annual Cyclical Changes in the Histological Features and Surface Ultrastructure in Ovaries of the Freshwater Featherback Notopterus notopterus (Pallas, 1769)

The feather back, Notopterus notopterus is an important food fish. Its ovary is an extremely dynamic organ and the oocytes present an asynchronous development. Variations in ovary weight, GSI, diameter of oocytes were studied in different months of the year in this fish. Different developmental stages of female germ cells were identified on the basis of histological and ultrastructural characteristics in the ovary of N. notopterus (Pallas). In the present investigation the oocyte development of N. notopterus was divided into five stages (oogonia, perinucleolar oocyte, cortical alveolus, yolk granules stage and mature oocyte). The cytophysiological features like vitellogenesis, chorion formation and atresia of some follicles were also studied in the present investigation. The seasonal changes in the ovary have been described according to the variations in gonadosomatic index and the cytological changes of the female germ line cells.     

Ovary cord structure and oogenesis in Hirudo medicinalis and Haemopis sanguisuga (Clitellata, Annelida): remarks on different ovaries organization in Hirudinea

In Hirudo medicinalis and Haemopis sanguisuga, two convoluted ovary cords are found within each ovary. Each ovary cord is a polarized structure composed of germ cells (oogonia, developing oocytes, nurse cells) and somatic cells (apical cell, follicular cells). One end of the ovary cord is club-shaped and comprises one huge apical cell, numerous oogonia, and small cysts (clusters) of interconnected germ cells. The main part of the cord contains fully developed cysts composed of numerous nurse cells connected via intercellular bridges with the cytophore, which in turn is connected by a cytoplasmic bridge with the growing oocyte. The opposite end of the cord degenerates. Cord integrity is ensured by flattened follicular cells enveloping the cord; moreover, inside the cord, some follicular cells (internal follicular cells) are distributed among germ cells. As oogenesis progresses, the growing oocytes gradually protrude into the ovary lumen; as a result, fully developed oocytes arrested in meiotic metaphase I float freely in the ovary lumen. This paper describes the successive stages of oogenesis of H. medicinalis in detail. Ovary organization in Hirudinea was classified within four different types: non-polarized ovary cords were found in glossiphoniids, egg follicles were described in piscicolids, ovarian bodies were found characteristic for erpobdellids, and polarized ovary cords in hirudiniforms. Ovaries with polarized structures equipped with apical cell (i.e. polarized ovary cords and ovarian bodies) (as found in arhynchobdellids) are considered as primary for Hirudinea while non-polarized ovary cords and the occurrence of egg follicles (rhynchobdellids) represent derived condition.     

Microtubule-like structures in developing oocytes of the mongolian gerbil (Meriones unguiculatus)

Oocytes of sexually mature Mongolian gerbils, Meriones unguiculatus, of all stages of the estrous cycle were investigated electron-microscopically during folliculogenesis. Oocytes of advanced stages of development contained numerous microtubule-like structures, which ran through the cytoplasm without any preference in direction. Initially they occurred in oocytes of secondary follicles. In the cross-section view they were either round showing an inner diameter of approximately 16 nm, or they were slightly triangle-shaped. Incomplete tubules were also present. The highest organization was found in oocytes of preovulatory follicles, whereas they vanished during atretic processes. A possible role of the tubules during the maturative growth of the oocyte is discussed.     

Structure of the Testes,Spermatozoa and Spermatozeugmata of Mimagoniates barberiRegan, 1907 (Teleostei: Characidae), an Internally Fertilizing,Oviparous Fish

Abstract The testis of Mimagoniates barberiis bipartite. Spermatogenic tissue is restricted to the anterior part. The posterior part of the testis is devoid of spermatogenic tissue and contains numerous efferent ducts filled with mature sperm. Cells in germinal cysts develop synchronously, sperm nuclei and flagella become oriented parallel in the late stages of spermiogenesis. In the caudal portion of the aspermatogenic part all sperms are arranged into unencapsulated sperm bundles — spermatozeugmata. Two types of spermatozeugmata are found both in the caudal portion of the testis and in milt. In the larger, spindle–shaped type, sperm flagella form the spindle tips. In the smaller ones, which have approximately a length of spermatozoon, the sperm are parallel and approximately in register. In both types sperm heads are arranged parallel. A mature spermatozoon is flail–shaped. The sperm head is highly elongated and situated alongside the flagellum, the tip of the head is directed backwards. Large mitochondria are situated on one side of the elongated nucleus only and form the tip of the head. Live spermatozoa move with the centriolar part ahead. Both testis and spermatozoon structure as well as formation of spermatozeugmata in M. barberiare highly derived features which perhaps evolved as adaptations to internal fertilization.     

Endothelial mitosis during the initial stages of corpus luteum neovascularization in the cycling adult rat

The initial stages of neovascularization of the corpus luteum were studied in cycling adult rats using light-microscopic autoradiography. The aim of this analysis was to determine whether endothelial mitosis is a factor in this vascular growth and whether there are differences in the amount of mitotic activity in various regions of the ovary. Ovaries were examined at two time intervals: 1-2 hr and 7-8 hr following ovulation. Animals received an intraperitoneal injection of tritiated-thymidine 20 min prior to perfusion fixation of the ovaries. Autoradiographic demonstration of tritiated-thymidine labeling in endothelial nuclei was considered an indication of DNA synthesis preceding mitosis. The percentage of labeled endothelial cells in the ovaries at both time intervals varied according to the region of tissue examined and the stage of differentiation of that region. Stromal vessels were less heavily labeled than thecal vessels. Thecal vessels surrounding growing follicles were more heavily labeled than those surrounding atretic follicles. The heaviest labeling was seen in the developing corpora lutea 7-8 hr following ovulation. Minimal labeling was evident in the corpora lutea which were formed in previous cycles. A regional difference was also detected in the ovarian mesothelium. The portion of the mesothelium overlying ovulated follicles and developing corpora lutea had the greatest percentage of labeled cells. The major findings of this study were: endothelial mitosis was elevated in the initial stages of luteal neovascularization; the heightened endothelial labeling was confined to specific regions of the ovary; and mesothelium in close proximity to the developing corpora lutea also displayed heightened DNA synthesis.     

Distribution of lectin-binding glycosidic residues in the hamster follicular oocytes and their modifications in the zona pellucida after ovulation.

In the present study, we have employed a battery of colloidal gold-tagged lectins as probes in conjunction with quantitative analysis to demonstrate the distribution and changes of carbohydrate residues in the hamster zona pellucida (ZP) during ovarian follicular development and during transit of the oocyte through the oviduct after ovulation. High-resolution lectin-gold cytochemistry performed on thin sections of LR White-embedded ovaries revealed a moderate to strong reactivity to WGA, PNA, DSA, AAA, and MAA over the entire thickness of the ZP of ovarian oocytes at different stages of follicular development. Labeling intensity over the ZP progressively increased as follicles matured in the ovary. In parallel, there was an association of labeling by gold particles with cortical granules, stacks of Golgi saccules, and complex structures called vesicular aggregates in the oocyte proper especially during the late stages of follicular growth. In contrary, labeling with each of HPA, DBA, and BSAIB(4) was absent in the ovary but was found to be localized over Golgi complexes and secretory granules in the non-ciliated secretory cells of the oviduct. When ovulated oocytes were labeled with each of HPA, WGA, RCA-I, PNA, DSA, BSAIB(4), AAA, MAA, and DBA, the ZP and several organelles in the oocyte proper presented a differential distribution of lectin-binding sites. Quantitative analysis was also performed on labeling by lectin-gold complexes that bind specifically to the ZP of mature follicular and ovulated oocytes. Quantitative evaluation revealed heterogeneous labeling between the inner and the outer zone of the ZP. A significant increase in the labeling densities in both inner and outer ZP was noted when tissue sections of ovulated oocytes were labeled with RCA-I or AAA. Tissue sections of ovaries labeled with WGA demonstrated a significant increase in the density of labeling in the outer layer of the ZP. Labeling by PNA, DSA, and MAA, however, showed a significant decrease in both the inner and outer portions of the ZP. Together, these results suggest that in the hamster, glycoproteins carrying specific sugar residues are added to the ZP of ovarian follicles during the early stages of folliculogenesis and are processed through a common secretory machinery, and that there is a significant change in both the sugar moieties and distribution of glycoproteins in the ZP following ovulation. Our results also showed that the hamster oviduct plays an important role in contributing certain glycoproteins to the ZP suggesting that the sugar moieties of these oviductal glycoproteins may have functional significance in fertilization.     

Molecular cloning and partial characterization of medaka fish stromelysin-3 and its restricted expression in the oocytes of small growing follicles of the ovary.

A cDNA clone (2755-bp) for stromelysin-3 was isolated by screening the cDNA library and by 3'- and 5'-rapid amplification of cDNA ends using ovary RNA of the medaka fish Oryzias latipes. The clone encodes a protein of 492 amino acids. Stromelysin-3 mRNA was detected only in the ovary. In situ hybridization analysis revealed that stromelysin-3 mRNA was localized in the oocyte cytoplasm of small growing follicles. RT-PCR analysis of total RNAs isolated from various-sized follicles and ovulated oocytes was conducted in order to determine the mRNA levels during oocyte growth. The stromelysin-3 mRNA level was the highest in the small follicles, and the mRNA levels decreased as the follicles grew. No significant stromelysin-3 mRNA was detected in the ovulated oocytes or immature ovaries. The fish stromelysin-3 cDNA was expressed in COS-1 cells in order to characterize the intracellular localization of the protein. A 56 kDa protein was synthesized and secreted into the culture medium. The secreted stromelysin-3 exhibited gelatin-degrading activity.     

The structure of the spiny mouse (Acomys cahirinus) ovary during development

The study presents the structure of the ovaries of the spiny mouse (Acomys cahirinus) during the first months of life. The ovaries in neonate females exhibit a large number of primordial and primary follicles, sometimes clustered in nests. The growing follicles were also observed within the ovary at that period. The first, early antral follicles appeared in the ovary during the second week of life. In the group of 60-day old females, the structure of the ovaries was characterized by a significant increase in the connective tissue elements. Moreover, ovarian follicles at various stages of development were observed, except for the antral ones with cumulus oophorus. The first mature follicles were identified in 3-month old females. In the ovarian follicles, apoptosis occurs at all stages of follicle development, especially in the early antral follicles. In the atretic follicles, apoptotic cells were identified in the layer of granulosa cells.     

Ultrastructure of the ovary and oogenesis in the polychaete Capitella jonesi (Hartman, 1959)

Ultrastructural features of the ovary and oogenesis in the polychaete Capitella jonesi (Hartman, '59) have been described. The ovaries are paired, sac-like follicles suspended by mesenteries in the ventral coelom throughout the midbody region of the mature worm. Oogenesis is unsynchronized and occurs entirely within the ovary, where developing gametogenic stages are segregated spatially within a germinal and a growth zone. Multiplication of oogonia and differentiation of oocytes into the late stages of vitellogenesis occur in the germinal region of the ovary, whereas late-stage vitellogenic oocytes and mature eggs are located in a growth zone. Follicle cells envelop the oocytes in the germinal zone of the ovary and undergo hypertrophy and ultrastructural changes that correlate with the onset of vitellogenesis. These changes include the development of extensive arrays of rough ER and numerous Golgi complexes, formation of microvilli along the surface of the ovary, and the initiation of extensive endocytotic activity. Oocytes undergo similar, concomitant changes such as the differentiation of surface microvilli, the formation of abundant endocytotic pits and vesicles along the oolemma, and the appearance of numerous Golgi complexes, cisternae of rough ER, and yolk bodies. Yolk synthesis appears to occur by both autosynthetic and heterosynthetic processes involving the conjoined efforts of the Golgi complex and rough ER of the oocyte and the probable addition of extraovarian (heterosynthetic) yolk precursors. Evidence is presented that implicates the follicle cells in the synthesis of yolk precursors for transport to the oocytes. At ovulation, mature oocytes are released from the overy after the overlying follicle cells apparently withdraw. Bundles of microfilaments within the follicle cells may play a role in this withdrawal process.     

Effects of pregnant mare serum gonadotropin (eCG) on follicle development and granulosa-cell apoptosis in the pig

The effect of eCG on follicular development and granulosa-cell apoptosis in sexually mature and immature gilts and on granulosa-cell apoptosis in vitro were studied. The sexually mature gilts were treated with eCG on Day 11 of the estrous cycle, and effects were analyzed at different times after treatment with untreated animals at corresponding stages of the cycle as controls. Apoptosis was determined by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL), hematoxylin and eosin staining, and DNA ladder. The proportion of apoptotic cells in atretic follicles (39%) was significantly higher (P<0.01) than that in healthy follicles (9%). At 24h after eCG treatment in mature gilts, the total number of follicles visible on the ovarian surface (57 per ovary), the number of small (<3mm) follicles (31.5 per ovary) and the number of medium-sized (3-5mm) follicles (23 per ovary) were significantly higher (P<0.05) than those of control animals (28, 20 and 6.5 per ovary, respectively), and declined gradually thereafter to below the level of control animals. The number of large (>or=5mm) follicles began to show a marked increase at 72h after eCG (8.5 versus 2.5, P<0.05). At 24h after eCG treatment, the proportions of apoptotic cells in small (7.2%) and medium-sized follicles (7.4%) were markedly lower (P<0.01) than those in controls (21.5 and 21%, respectively) and increased gradually thereafter to approach the level in controls. The percentage of apoptotic cells in large follicles (10% at 24h post-eCG) did not change significantly. Before eCG treatment, there were markedly fewer follicles of all types on ovaries of immature gilts than of mature gilts (9 versus 25 per ovary) and the proportion of apoptotic cells in small and medium follicles was high (25 and 34%, respectively). After eCG treatment, the changes in follicle number and proportion of apoptotic cells in the immature gilts followed a similar pattern to that of the mature gilts. Equine chorion gonadotropin inhibited apoptosis of granulosa cells cultured either in vitro or in intact follicles in a dose-dependent manner. Thus, follicular atresia in the pig, as in other animals, was characterized by apoptosis of large numbers of granulosa cells, and eCG promoted follicular development by inhibition of granulosa-cell apoptosis.     

Testicular,spermatogenesis and sperm morphology in Martarega bentoi (Heteroptera: Notonectidae)

The testicular, spermatogenesis and sperm morphology of the backswimmer Martarega bentoi was described using light and transmission electron microscopy. In this species, a pair of testes, two deferent ducts, two different pairs of accessory glands, and an ejaculatory duct form the male reproductive system. Each testis consists of two testicular follicles, which are arranged side by side in snail shape. The follicles are filled with cysts at different stages of spermatogenesis, but in the same cyst the germ cells (up to 64) are in the same stage. At the end of spermatogenesis, the sperm cells are very long, with the flagellum measuring approximately 2500 μm in length, the nucleus only 19 μm, and the acrosome, with two distinct regions, 300 μm. The flagellum is composed of an axoneme, with a 9 + 9 + 2 microtubular pattern, and 2 asymmetric mitochondrial derivatives (MDs). These have the anterior ends inserted into two cavities at the nucleus base, exhibit two paracrystalline inclusions, and have bridges linking them to the axoneme. Few spermatozoa per cyst, asymmetry in size and shape of the MDs, as well as their insertion at the nuclear base are characteristics considered derived, and that differentiate the sperm of M. bentoi from those of the Nepomorpha, Belostomatidae and Nepidae.