Seminiferous Lobules Research Articles

In silico analysis, seasonal variation and gonadotropic regulation of jag1 and its receptor notch1 in testis of spotted snakehead Channa punctatus

The present study in seasonally breeding spotted snakehead Channa punctatus, for the first time in nonmammalian vertebrates, demonstrated correlation between reproductive phase-dependent testicular expression of ligand Jag1/receptor Notch1 and spermatogenic events. Testicular transcriptome sequencing data from our earlier study in C. punctatus was used in the present study to select the best transcript for jag1 (cpjag1) and notch1 (cpnotch1). The transcripts cpjag1 and cpnotch1 encoded full-length putative proteins of 1215 (cpJag1) and 2475 (cpNotch1) amino acids, respectively. A marked homology in the extracellular domains of Jag1 and Notch1 was observed following their alignment with respective proteins from different vertebrates, suggesting conservation in ligand-receptor interaction in C. punctatus. Both cpJag1 and cpNotch1 showed phylogenetic closeness with their teleostean counterparts, especially with that of Perciformes. Temporal expression of cpjag1 and cpnotch1 in testis depending on reproductive phases showed an appreciably high expression during spermatogenically inactive resting and postspawning phases when seminiferous lobules consisted of spermatogonial stem cells and undifferentiated spermatogonia. Their expression sharply declined during spermatogenically active preparatory and spawning phases. It appears that involvement of cpjag1/cpnotch1 is restricted to inactive phases when spermatogonial stem cells renew themselves and replenish undifferentiated spermatogonia. This assumption is ascertained by an experimental study in which high level of testicular cpjag1/cpnotch1 expression in control fish of resting phase markedly decreased after administration of human chorionic gonadotropin that is known to induce proliferation and differentiation of spermatogonia and spawning of spermatozoa.

Morphometric and histological features of the testicles of cultured male broodstock African Catfish (Clarias gariepinus) at different ages

Testicular tissues obtained from 25 apparently healthy broodstock African Catfish (Clarias gariepinus) of 6, 8, 9, 10 and 12 months old were used to investigate the morphological adaptations of the testicles suitable for reproductive exercises. The result showed that the mean gonadosomatic indices of the pooled testicles of the catfish increased linearly from 0.30 ± 0.02, 0.34 ± 0.01, 0.45 ± 0.09 at 6, 8, and 9 months of age respectively and peaked at 12 months with a GSI value of 0.61±0.13. Moreover, the epithelial height of the seminiferous tubules of 9 month old catfish was significantly (P<0.05) higher than the epithelial heights of the 6, 8, 10 and 12 month old fish. The luminal diameters of the seminiferous tubules of the testicles of 10 and 12 months old catfish were significantly (P<0.05) higher than the luminal diameters of the 6, 8 and 9 months old fish. The encapsulated testicles of the catfish exhibited seminiferous lobules which contained spermatogenic cells in cysts. However, at 10 months, there were partial distortion of the cystic distribution of the spermatogenic cells and occasional loss of the germinal epithelium while evidences of necrosis of some of the cells of the seminiferous epithelium were recorded in the testicles of 12 months old fish. Finally, the present study has provided morphological evidences that the use of gonadosomatic indices alone in the determination of the reproductive state of a fish population may give an erroneous picture and that the 8 and 9 months old broodstock African Catfish (Clarias gariepinus) may be most suitable for breeding exercises.

UCHL1 expression and localization on testicular development and spermatogenesis of Chinese giant salamanders.

Ubiquitin carboxyl-terminal hydrolase L1 (UCHL1), which is extensively expressed in vertebrates, is a deubiquitinating enzymes that inhibits the degradation of proteins by reversing ubiquitination modification. Herein, a 1087-bp sequence encoding UCHL1 was identified from the Chinese giant salamander (CGS; Andrias davidianus). The coding sequences (CDS) of UCHL1 encoded a putative poly peptide of 222 amino acids. The CGS UCHL1 isoforms were more related to their human and mouse counterparts. The phylogenic tree of vertebrate UCHL1 indicated that CGS UCHL1 has the closest relationship with human UCHL1 (up to 73.99 %). Before the gonads of male CGSs matured, the peak level of UCHL1 expression in testes appeared in 3-year-old CGSs according to RT-qPCR and western blot. In adult testes, the level of UCHL1 protein was lower in the breeding period than in the post-breeding period, whereas the level of UCHL1 protein in interstitial fluid of adult CGS testes was higher during the breeding period than during the post-breeding period. In testicular seminiferous lobules in the developmental stage of CGSs, immunohistochemistry displayed three kinds of localizing patterns of UCHL1, including nuclear localization at half year old, cytoplasmic localization from one year to three years old, and extracellular localization in adult. In testicular seminiferous lobules of adult CGS, the different developmental germ cells were separated by cysts containing UCHL1 protein, but UCHL1 did not localize on the mature sperm. The results showed that extracellular UCHL1 loaded on exosomes, as a component of the homogeneous germ cell cysts, could regulate the synchronous development of sperm in testes of adult CGS.

Rearing in captivity affects spermatogenesis and sperm quality in greater amberjack, Seriola dumerili (Risso, 1810)1

The greater amberjack, Seriola dumerili (Risso, 1810), is a promising candidate for the diversification of European aquaculture production, but inconsistent reproduction in captivity prevents commercial production. Recent studies showed that greater amberjack confined in sea cages exhibited scarce gonad development and early interruption of gametogenic activity during the reproductive season. The aim of the present study was to improve our understanding of the observed impairment of spermatogenesis. Adult wild and captive-reared males were sampled during 3 different phases of the reproductive cycle: early gametogenesis (EARLY; late April to early May), advanced gametogenesis (ADVANCED; late May to early June), and spawning (SPAWNING; late June to July). Spermatogonial stem cells and proliferating germ cells were identified through the immunohistochemical localization of Pou5f1 and proliferating cell nuclear antigen, respectively. Apoptotic germ cells were identified throughout the terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate nick end labeling method. Sperm quality of captive-reared fish was evaluated using computer-assisted sperm analysis. Captive-reared males exhibited seminiferous lobules of a smaller diameter, a precocious and progressive decrease of spermatogonial mitosis, and a high level of apoptosis at the beginning of the reproductive season, concomitant with a many-fold higher 17β-estradiol plasma concentration. The motile spermatozoa percentage of captive greater amberjack was lower than in other teleosts, and a drastic decrease of spermatozoa motility duration, velocity, and ATP content occurred along the reproductive season. An abnormal increase of sperm concentration as well as an increase of dead spermatozoa occurred during the SPAWNING phase, probably because of lack of sperm hydration and ejaculation and consequent sperm ageing. The present study demonstrates the extreme susceptibility of greater amberjack to rearing stress and underscores the need for improvement of the rearing and handling procedures to ameliorate gametogenesis dysfunctions in commercial aquaculture production.

Gonadal morphogenesis and sex differentiation in cultured Ussuri catfish Tachysurus ussuriensis.

The objective of this study was to investigate the optimal developmental time to perform sex reversal in Ussuri catfish Tachysurus ussuriensis, to develop monosex breeding in aquaculture. Systematic observations of gonadal sex differentiation of P. ussiriensis were conducted. The genital ridge formed at 9 days post fertilization (dpf) and germ cells begin to proliferate at 17 dpf. The ovarian cavity began forming on 21 dpf and completed by 25 dpf while presumptive testis remained quiescent. The primary oocytes were at the chromatin nucleolus stage by 30 dpf, the peri-nucleolus stage by 44 dpf and the cortical alveoli stage by 64 dpf. The germinal vesicle migrated towards the animal pole (polarization) at 120 dpf. In presumptive testis, germ cells entered into mitosis and blood vessels appeared in the proximal gonad on 30 dpf. The efferent duct anlage appeared on 36 dpf and formation of seminal lobules with spermatogonia and lobules interstitium occurred at 120 dpf. Therefore, gonadal sex differentiation occurred earlier in females than in males, with the histological differentiation preceding cytologic differentiation in T. ussuriensis. This indicates that undifferentiated gonads directly differentiate into ovary or testis between 17 and 21 dpf and artificial induction of sexual reversal by oral steroid administration must be conducted before 17 dpf.

Rearing in captivity affects spermatogenesis and sperm quality in greater amberjack, Seriola dumerili (Risso, 1810).

The greater amberjack, (Risso, 1810), is a promising candidate for the diversification of European aquaculture production, but inconsistent reproduction in captivity prevents commercial production. Recent studies showed that greater amberjack confined in sea cages exhibited scarce gonad development and early interruption of gametogenic activity during the reproductive season. The aim of the present study was to improve our understanding of the observed impairment of spermatogenesis. Adult wild and captive-reared males were sampled during 3 different phases of the reproductive cycle: early gametogenesis (EARLY; late April to early May), advanced gametogenesis (ADVANCED; late May to early June), and spawning (SPAWNING; late June to July). Spermatogonial stem cells and proliferating germ cells were identified through the immunohistochemical localization of and proliferating cell nuclear antigen, respectively. Apoptotic germ cells were identified throughout the terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate nick end labeling method. Sperm quality of captive-reared fish was evaluated using computer-assisted sperm analysis. Captive-reared males exhibited seminiferous lobules of a smaller diameter, a precocious and progressive decrease of spermatogonial mitosis, and a high level of apoptosis at the beginning of the reproductive season, concomitant with a many-fold higher 17β-estradiol plasma concentration. The motile spermatozoa percentage of captive greater amberjack was lower than in other teleosts, and a drastic decrease of spermatozoa motility duration, velocity, and ATP content occurred along the reproductive season. An abnormal increase of sperm concentration as well as an increase of dead spermatozoa occurred during the SPAWNING phase, probably because of lack of sperm hydration and ejaculation and consequent sperm ageing. The present study demonstrates the extreme susceptibility of greater amberjack to rearing stress and underscores the need for improvement of the rearing and handling procedures to ameliorate gametogenesis dysfunctions in commercial aquaculture production.

Testicular Morphology and Sperm Motility in Cultured African Catfish (<i>Clarias gariepinus</i>) at Different Stages of Development

Testicular morphology and sperm motility were evaluated in cultured Clarias gariepinus (n = 25) purposively assigned to five groups according to their age. The results showed that the testes were paired, elongated, dorso-ventrally flattened structures, situated in the caudal aspects of the body cavity. The mean length of both right and left testes increased linearly with age, being significantly (p < 0.05) higher at 6 months than at 4 and 5 months of age, and also significantly (p < 0.05) higher at 8 months than at 6 months of age, while the mean weight and organo-somatic index of the catfish testes increased linearly until 6 months of age, after which no significant (p > 0.05) increase in the testicular weight and organo-somatic index was observed. Unidirectional progressive movement of spermatozoa was detected in the milt of C. gariepinus at 6, 7 and 8 months of age, but sperm cells were non-motile at 4 and 5 months of age. Histological sections showed seminiferous lobules, whose germinal epithelia were characterized by many cysts enclosing clones of sperm cells. Each cyst enclosed a clone of sperm cells at an identical stage of spermatogenesis. Spermatids and spermatozoa were present in the lumen of the seminiferous lobule. The obtained results indicate that the morphology of the testes of C. gariepinus is similar to the testes of members of the order Siluriformes, but sexual maturity and production of motile spermatozoa may be achieved at 6 months of age in the African catfish.

Influence of low temperature on structure and dynamics of spermatogenesis during culture of Oreochromis niloticus

Understanding the influence of different temperature conditions on the spermatogenesis is important for improvement of the fish aquaculture. This study evaluated the influence of low temperature on structural and quantitative dynamics of the spermatogenesis in Oreochromis niloticus. Adult males were cultivated with room temperature water (20.28–22.46°C) and testes were collected for histological, ultrastructural and morphometric analyses. This species has unrestricted lobular testis with cystic spermatogenesis and type I spermiogenesis that results in a single anacrosomal aquasperm. Seminiferous lobules and spermatogenic cells had a radial arrangement toward the spermatic duct. Superior and central portions of testes had a greater lobular area than the inferior portion in all samplings. Spermatogonia (9.3%) were distributed in the inferior portion of testes, spermatocytes (25.3%) and spermatids (34.4%) in the central portion, while spermatozoids (39.4%) and secretory cells (4.6%) in the superior portion. Throughout the study, correlation between water temperature and lobular area characteristics was significant only in the inferior portion of testes (r2=0.95), although the lobular area in the other testicular portions increased when the water temperature increased by 2°C. Correlation between the water temperature and spermatogenic cells was significant for undifferentiated spermatogonia (r2=0.54) and number of spermatids (r2=0.67). It is concluded that low cultivation temperatures may positively influence the generation of primary spermatogonia in the inferior periphery of O. niloticus testes. In addition, males maintain reservoirs of germ cells at low temperatures and the radial zonation of spermatogenesis has an important role in the renewal and production of germ cells.

Reproduction Control Of Male Oreochromis Niloticus (Nile Tilapia) Using Gossypium Herbaceum (Cotton) Root Bark Meals As Fertility Inhibitor

The study was carried out to control Tilapia population using Gossypium herbaceum root bark meal (GHRBM) as reproduction inhibitor. Gossypium herbaceum (Cotton) root bark meal was fed to male O. niloticus (31.38±0.67g). The root bark was added to a basal diet (35% crude protein) at 0, 5, 10, 15 and 20 g/kg diet. A total of 75 fishes were randomly distributed in triplicate into 15 plastic tanks (1x1x1m and 1.45 inches thick) at a stocking density of 5 fishes per 1m3. Groundwater of 400 litres volume was maintained throughout the period of experiment. The pH value was between 6.90 and 7.67, temperature ranged between 25.4 and 26.60C and dissolved oxygen concentration between 2.8 and 3.9 ml/l. The fish was fed at 4% body weight/day in two instalments at 09:00-09:30 hour and 17:00-17:30 hour. In fish fed 0g of GHRBM/kg diet, histological examination showed spermatocytes released into the lumen of the seminiferous tubules while in fish fed 5 g, 10 g, 15 g and 20 g GHRBM/kg diets, the sections showed eroded connective tissue, hydropic degeneration, disintegration in seminiferous lobule, damaged connective tissue and increased in interstitial cells. Except in the control treatment, it was observed that O. niloticus spermatozoa maintained normal morphology but low sperm count and low volume. Milt volume and milt count (P<0.05) decreased with increase in concentration of treatments used (from 0.5 to 0.1ml and 3.59 x109 to 0.33 x109 (Sperm/ml) respectively. Weight gained was highest in fish fed 10g GHRB/kg diet. It was observed that the feeding of Gossypium herbaceum root bark meals had no effect on water quality. Histological observations and milt analysis revealed that Gossypium herbaceum root bark may be effective as reproduction inhibitor in O. niloticus.

Ultrastructural Studies of Germ Cell Development and the Functions of Leydig Cells and Sertoli Cells associated with Spermatogenesis in Kareius bicoloratus (Teleostei, Pleuronectiformes, Pleuronectidae).

The ultrastructures of germ cells and the functions of Leydig cells and Sertoli cells during spermatogenesis inmale Kareius bicoloratus (Pleuronectidae) were investigated by electron microscope observation. Each of the well-developed Leydig cells during active maturation division and before spermiation contained an ovoid vesicular nucleus, a number of smooth endoplasmic reticula, well-developed tubular or vesicular mitochondrial cristae, and several lipid droplets in the cytoplasm. It is assumed that Leydig cells are typical steroidogenic cells showing cytological characteristics associated with male steroidogenesis. No cyclic structural changes in the Leydig cells were observed through the year. However, although no clear evidence of steroidogenesis or of any transfer of nutrients from the Sertoli cells to spermatogenic cells was observed, cyclic structural changes in the Sertoli cells were observed over the year. During the period of undischarged germ cell degeneration after spermiation, the Sertoli cells evidenced a lysosomal system associated with phagocytic function in the seminiferous lobules. In this study, the Sertoli cells function in phagocytosis and the resorption of products originating from degenerating spermatids and spermatozoa after spermiation. The spermatozoon lacks an acrosome, as have been shown in all teleost fish spermatozoa. The flagellum or sperm tail of this species evidences the typical 9+2 array of microtubules.

The Male Urogenital System of the Siberian Salamander Salamandrella keyserlingii (Caudata: Hynobiidae) with Special Reference to the Microstructure of the Testes and Sperm Transport Complex

The gross anatomy of the urogenital system and histology of the testes and sperm transport system in adult male Salamandrella keyserlingii from southeast of Western Siberia were examined. The general structure of the male urogenital system in S. keyserlingii was similar to that of other hynobiids. Testes were monolobed and bean shaped. No spermatogenic wave through the longitudinal axis of the testes was observed. However, a «lobular wave» with zonal distribution of cysts at different sperm maturation stages was observed along the proximo-distal axis of each seminiferous lobule. From the testes to the cloaca, the sperm transport system included the vasa efferentia, longitudinal collecting ducts of the vasa efferentia, nephrons of the genital kidneys, collecting ducts, and Wolffian ducts.

A histological study of testis development and ultrastructural features of spermatogenesis in cultured Acrossocheilus fasciatus.

Testis development and ultrastructural features of spermatogenesis in Acrossocheilus fasciatus (Cypriniformes, Barbinae), a commercial stream fish, were studied using light and electron microscopy. The reproduction cycle in A. fasciatus testes is classified into six successive stages from Stage I to Stage VI. Based on an analysis of previous results, May to July can be confirmed as the best breeding season for A. fasciatus males. During this time, the A. fasciatus testes are in Stage V and the sperm in males is most abundant. In the first reproductive cycle, sexually mature male testes return to Stage III in October, subsequently overwintering at this stage. In the lobular-type testes of A. fasciatus, cystic type spermatogenesis occurs with restricted spermatogonia. All spermatogenic cells at different stages are distributed along the seminiferous lobules, which contain spermatogonia, spermatocytes, spermatids and spermatozoa. At the end of spermatogenesis, spermatogenic cysts open to release spermatozoa into the lobule lumen. Ultrastructural observation of A. fasciatus spermiogenesis reveals that electron-dense substances appear at the different stages of germ cells, from primary spermatogonia to secondary spermatocytes. We have termed these dense substances as "nuage" when free in the cytoplasm or adjacent to the nuclear envelope, while those close to the mitochondria are called inter-mitochondrial cement. The spermatozoa in A. fasciatus can be classified as type I due to the presence of nuclear rotation. Although the nuclear chromatin in the head of sperm was highly condensed, no acrosome was formed. The cytoplasmic canal, a common ultrastructural feature of Teleostei spermatozoa, was also present in the midpiece. In addition, numerous fused mitochondria were observed. The distal centriole and proximal centriole constituting the centriolar complex were oriented incompletely perpendicular to each other. The flagellum showed a typical 9+2 arrangement pattern. Conversely, our study on A. fasciatus yielded no information concerning the lateral fins although an enlarged saclike area was present at the end of some flagella.

Structural and functional effects of early exposure to 4-nonylphenol on gonadal development of Nile tilapia (Oreochromis niloticus): b-histological alterations in testes.

The present study investigates the effects of different doses (0, 40, 60, 100 μg/L) of 4-nonylphenol (NP) on testis histology and sperms motility of mature Oreochromis niloticus. A tendency for a dose-dependent reduction in the gonado-somatic index (GSI) in the NP-exposed groups was observed. Histological examination revealed that high doses of NP (60 and 100 μg/L) cause hyperplasia of interlobular connective tissue components coincide with decrease in the size of seminiferous lobules and amount of lumen spermatozoa in comparison with the control and low-dose (40 μg/L)-exposed groups. In addition, within the seminiferous lobules, rupture of spermatogenic cysts, vacuolation and necrosis of primary spermatocytes due to damage of sertoli cells were clearly observed and lead to decrease in advanced spermatogenic cells. The highest dose caused significant decrease in the GSI associated with appearance of testis-ova (intersex) state. The percentage of abnormal sperms increased with increasing the dose of NP reaching to 96 % for those subjected to 100 μg NP/L, while it was only 11 % for the control group specimens. The study indicates that NP has estrogenic potency induced marked alteration in the sexual development including inhibition in testicular growth and deformation in the sperms.

Germ-line activation of the luteinizing hormone receptor directly drives spermiogenesis in a nonmammalian vertebrate.

In both mammals and teleosts, the differentiation of postmeiotic spermatids to spermatozoa (spermiogenesis) is thought to be indirectly controlled by the luteinizing hormone (LH) acting through the LH/choriogonadotropin receptor (LHCGR) to stimulate androgen secretion in the interstitial Leydig cells. However, a more direct, nonsteroidal role of LH mediating the spermiogenic pathway remains unclear. Using a flatfish with semicystic spermatogenesis, in which spermatids are released into the seminiferous lobule lumen (SLL), where they develop into spermatozoa without direct contact with the supporting Sertoli cells, we show that haploid spermatids express the homolog of the tetrapod LHCGR (Lhcgrba). Both native Lh and intramuscularly injected His-tagged recombinant Lh (rLh) are immunodetected bound to the Lhcgrba of free spermatids in the SLL, showing that circulating gonadotropin can reach the intratubular compartment. In vitro incubation of flatfish spermatids isolated from the SLL with rLh specifically promotes their differentiation into spermatozoa, whereas recombinant follicle-stimulating hormone and steroid hormones are ineffective. Using a repertoire of molecular markers and inhibitors, we find that the Lh-Lhcgrba induction of spermiogenesis is mediated through a cAMP/PKA signaling pathway that initiates the transcription of genes potentially involved in the function of spermatozoa. We further show that Lhcgrba expression in germ cells also occurs in distantly related fishes, suggesting this feature is likely conserved in teleosts regardless of the type of germ cell development. These data reveal a role of LH in vertebrate germ cells, whereby a Lhcgrba-activated signaling cascade in haploid spermatids directs gene expression and the progression of spermiogenesis.

Seasonal Histological Changes in Gonads of the Catfish (CLARIAS LAZERA)

Forty mature catfish of both sexes (n=10 per season; 5 males and 5 females) were used to study the effect of different seasons on the histological and histochemical structure of the gonads. The histological results showed that both testes and ovaries of the catfish were degenerated during winter that was considered as a resting season of the catfish gonadal activity. Both testes and ovaries began to restore their intact and fully mature structure during spring and continue the same during summer where the testes show distended seminiferous lobules with all spermatogenic cells and spermatozoa also, the ovaries showed the different developmental stages including mature follicles therefore, both spring and summer were considered as spawning season of the catfish. During autumn, both testes and ovaries appeared as spent gonads where the testes showed many empty seminiferous lobules and the ovaries showed many atretic follicles therefore, autumn was considered as post-spawning or spent season. The results of Gonado-Somatic Index (GSI) were coincided with the histological structure of the gonads where they show peak value during spring and summer (spawning season) and showed the lowest value during winter (resting season).

Ultrastructure features of spermiogenesis and spermatozoa of sparid fish Rhabdosargus sarba (Forsskål, 1775) from Red SEA, Jeddah coast

Transmission and scanning electron microscopy were used to investigate the ultrastructure of spermatogenesis of the Sparid fish Rhabdosargus sarba. The testis is lobular in shape and spermatogensis is of unrestricted type. Spermatogonia occur isolated or in clusters within the seminiferous lobules. The germ cells are found in cysts formed by sertoli cell processes. Cells within cysts are found in the same developmental stage. Spermiogenesis is characterized by chromatin condensation, movement of the centrioles, flagellum development, nuclear rotation, nuclear indentation and nuclear fossa formation, reduction of the cytoplasm and differentiation of the flagellar complex. Ultrastructurally the spermatozoa of R. sarb belonges, like that of other sparid fish, to the teleosean type 1 spermatozoan with the flagellum axis perpendicular to the nuclear fossa. It has an ovoidal head, a short, cylindrically shaped midpiece and a long tail region. The nucleus reveals a deep invagination (nuclear fossa) in which the centrriolar complex is located, and a satellite nuclear noch shaped like a bell. The centriolar complex lies inside the nuclear fossa and is composed of a proximal and a distal centriole. The two centerioles are perpendicular to each other. The distal centriole is traversed by a conspicuous basal plate in its base. At the neck of the flagellum the necklace is observed. A nuclear noch is located above the proximal centeriol. The short midpiece houses two spherical mitochondria. The flagellum is inserted medio-laterally into the head, contains the conventional 9+2 axoneme.

Ultrastructural studies of spermatogenesis and the functions of Leydig cells and Sertoli cells associated with spermatogenesis in Larimichthys polyactis (Teleostei, Perciformes, Sciaenidae)

Ultrastructural studies of spermatogenesis and the functions of Leydig cells and Sertoli cells were investigated by electron microscope observation. Ultrastructural characteristics of spermatozoa of Larimichthys polyactis (Sciaenidae) have a round head, a nucleus containing highly compact filamentous clusters of chromatin, slightly eccentric nuclear fossa, no acrosome, a short midpiece with a short cytoplasmic channel, and a flagellum showing the classic axoneme structure (9 + 2) and short irregular flagellum lateral fins. The spermatozoon of this species (Sciaenidae) is Perciformes type II: the flagellar axis is parallel to the nucleus, the centriolar complex is outside the nuclear fossa, the proximal centriole is anterior and perpendicular to the distal centriole, and no more than five spherical mitochondria are observed. Each of the well-developed Leydig cells observed during the periods of active meiotic division and before spermiation contains an ovoid vesicular nucleus; a number of smooth endoplasmic reticulum, tubular, or vesicular mitochondrial cristae; and several lipid droplets within the cytoplasm. This indicates that Leydig cells, as typical steroidogenic cells showing several cytoplasmic characteristics, are involved in male steroidogenesis. However, no clear evidence of steroidogenesis or of any transfer of nutrients from the cells to spermatids that appears to be associated with phagocytic function in the seminiferous lobule was observed for Sertoli cells. These findings indicate that Sertoli cells of this species function in phagocytosis and the resorption of products originating from degenerating spermatids and spermatozoa following spermiation.

Morphological and Histomorphological Structure of Testes of the Catfish "Clarias Gariepinus" From Egypt

Knowledge of the normal reproductive biology of catfish is of a great importance not only for better understanding of the theory of fish development, but also to be used as a baseline for understanding the pathological changes results form exposure to harmful toxicants. Thus, the aim of the current study was to elucidate the gross anatomical and light microscopic features of the testes of the catfish "Clarias gariepinus" from Egypt. The present study was carried out on 36 mature male catfish (Clarias gariepinus) collected monthly during the spawning period (April-September) throughout the Nile River, crossing Sohag city in Egypt, in the year 2011. Samples were processed for light and electron microscopy. Each testis consisted of two regions, a fringed outer lateral region and a smooth sagittal-medial region. Histological examination revealed that the testis was covered with a highly vascular connective tissue capsule sending septa dividing the testis into seminiferous lobules separated by interstitial connective tissue containing steroid secreting Leydig cells. Seminiferous lobules were made up of spermatogenic cells and Sertoli cells; the spermatogenic cells located within cysts formed by the cytoplasmic projections of the Sertoli cells. According to the maturation stages, the seminiferous lobules were classified into three types. Spermatogenic seminiferous lobules were lined with different spermatogenic cells but had few or no spermatozoa. Pubertal seminiferous lobules were packed with spermatozoa with few spermatogenic cells. Spent seminiferous lobules contained remnants of spermatozoa and spermatogenic cells. In conclusion, the testis of catfish Clarias gariepinus from Egypt was similar in structure to other catfish and teleost species.

Histopathological Effects of Mercury on Male Gonad and Sperm of Tropical FishGymnotus carapo in vitro

Hg is toxic metal mostly due to adverse effects on structure and function of tissues and organs in humans and animals. Male reproductive systems of fish species are also sensitive to Hg action. However, the histological alterations in tropical fish testis are less known and little information is available concerning the underlying mechanisms of metal pathogenesis in reproductive functions. Further investigations dealing with Hg direct effects on tissue and organs of tropical species are a need. The present study investigated HgCl2 toxic effects in testes and sperms of tropical fish Gymnotus carapo. The histopathology, germ cell structure and number were analysed to elucidate the pathological process during exposure to increasing metal concentrations (1 μM – 30 μM). Fishes exposed to 20μM and 30μM reached testicular Hg concentrations of 5.1 μg.g−1 and 5.2 μg.g−1, respectively. No significant alterations in gonadosomatic index (GSI) occurred between control, and Hg exposed fishes. Untreated fishes showed characteristic organization of testicular tissue, with germ epithelium organized in cysts where spermatogenesis occurs. Germ cells and spermatozoa are seen an inner the cysts. HgCl2 induced severe damages characterized by complete disorganization of seminiferous lobules, proliferation of interstitial tissue, congestion of blood vessels, reduction of germ cells and sperm aggregation. Exposed fishes showed a decrease in the sperm’s number. Initial reduction of a sperm’s number (36,8%) was observed after 20 μM/24h treatment and subsequent decrease (48,7%) was observed after 20μM/96h. Hg (20μM) also altered sperm morphology in 24h and 96h where sperm head abnormalities were present. In conclusion, the present study showed HgCl2 progressive damages in testicular tissue, sperm count and morphology of tropical species Gymnotus carapo. The effects in testicular tissues were observed since low Hg concentrations. These results are important to establish a direct correlation between the mercury accumulation and severity of lesions.

Ultrastructural study of spermatogenic stages in the protandrous sparid fish Diplodus cervinus cervinus (Lowe, 1838) from the South Eastern Mediterranean coast

The current study was designed to study the ultrastructure of the spermatogenic stages of the protandrous hermaphrodite sparid Diplodus cervinus cervinus. Although, it is a useful tool to enhance understanding of germ cells differentiation in this economic species, none of the available references paid attention to the studied species. The testis of the studied specie is tubular in shape and the germ cells are arranged in cysts or clusters within the seminiferous lobules. Spermatogenesis occurs in several places along the length of each lobule and induced by the action of the somatic steroidogenic secretory cells which are known as Leydig cells. Such cells contained four main morphological structural characteristics a vesicular nucleus, ovoid and elongated mitochondria with tubular cristae, a number of smooth endoplasmic reticula, and a considerable amount lipid droplets in the cytoplasm. Spermatogenic cyst displays round shaped cells with large nuclei containing clumps of heterogenic dense chromatin and reduced cytoplasm known as primary spermatogonia. They undergo a series of mitotic divisions to reach the secondary spermatogonia stage; such cells irreversibly divide meiotically to form primary and secondary spermatocytes. Spermatids are seen in different stages of spermiogenesis, as indicated by the degree of chromatin condensation. They underwent a shape remodeling and a size reduction during spermiogenesis as the morphology of the spermatid nucleus gradually changed and several mitochondria and centrosomes moved to a position just behind the nucleus of the spermatid. Spermatozoan ultrastructure showed that it is anacrosomal primitive teleostean type (type I) with round head, the posterior part of the nucleus is indented a nuclear fossa which displays a bell-shaped in longitudinal section and circular in transverse section containing centeriolar complex, part of the basal body and cytoplasm. The chromatin is heterogeneously granular, high electron-dense containing tightly packed fibers. The mid piece is short containing mitochondrial ring which consists of spherical or ovoid mitochondria. The axoneme consists of nine double outer tubules and single microtubular constructions. In conclusion, the testis structure could be described as the unrestricted spermatogonial testicular type. More attention should be rewarded to the female of this species in order to give a clear view about the process of oogenesis. Key words: Spermatogenesis, Sparid, protandrous, hermaphrodite, anacrosomal, primitive teleostean spermatozoa.