Presence Of Spermatocytes Research Articles

Sexual maturation in male bowhead whales (Balaena mysticetus) of the Bering-Chukchi-Beaufort Seas stock

Since the mid-1970s, study has focused on reproductive biology of female bowhead whales, while little has been described for males. This study evaluates testicular morphology (mass and length) and histology in relation to body length to determine the onset of male sexual maturity. Mean testis mass and mean testis length were highly correlated. Body length and mean testis mass were significantly correlated and an inflection of increased testicular mass occurred at approximately 12.5-13.0m suggesting the onset of puberty, and also indicated by histologic findings. Biological variability and the fact that few male animals have been examined within this critical length cohort do not allow determination of the onset of maturity with higher precision. Too few mature males have been landed in spring to make statistical comparisons of testes mass with autumn-landed animals within specific size cohorts. Two large (15.7m and 17.7m) males landed in spring had relatively small inactive testes and were diagnosed as pseudohermaphrodites; body length and mean testis length and seminiferous tubule diameter (STD) were not correlated with the other ‘normal’ whales. The smallest male confirmed as mature based on the presence of spermatocytes was 12.7m. The largest testes measured (combined mass 203kg) were from a whale landed in autumn. Mean STD for individual whales ranged from 33.3-170.9m and increased with mean testis weight and whale length. The STD is similar within a testis regardless of region evaluated, with minor variability. Some variation was noted for transverse sections within a cross section for some whales but no pattern was evident.

Aspects of the Biology of <i>Periophthalmus barbarus </i>(Mudskipper), from Jaja Creek, Niger Delta, Nigeria

The mudskipper, <i>Periophthalmus barbarus</i> is reported to be a good delicacy for human consumption as well as for use in traditional medicinal preparations where aphrodisiac properties are attributed to its flesh. They are investigated for their biological and eco-toxicological studies, to determine its potential use as a bio-indicator in environmental assessments of coastal waters, tropical or subtropical soft bottom intertidal systems, and despite this; there is lacuna of scientific report on its biology and ecology. This research was undertaken to provide information on the aspects of the biology of the species, with reference to sexual dimorphism, sex ratio, size composition, gonad morphology and morphogenesis, length weight relationship and condition index. Monthly samples were collected at Jaja creek, Niger Delta, Nigeria and preserved in 10% formalin for further analysis. Length and weight of each specimen were measured and weighed to the nearest 0.1 cm and 0.001 g respectively; the specimens were later dissected to examine the gonads. Ovaries and testes from each specimen were measured and weighed to the nearest 0.001 g and 0.1 cm respectively. Paired comparison by the observation of the genital papilla on the postero-ventral surface of the abdominal region was used to determine sexual dimorphism in weight in similarly-sized females and males. The proportion of the two sexes relative to one another was used to calculate the sex ratio. Each specimen was measured using a fish measuring board to the nearest centimeter and weighed using a meter balance to nearest gram and recorded to obtain size composition. The length-weight (L-W) relationship was computed using empirical allometric equation. Findings reveal that the presence of spermatocytes and oocytes at different stages of development was an indication that this species belongs to the fish with prolonged and fractional spawning season and therefore, may spawn more than once during the spawning season. The mean condition index of 1.06 proved that the fish fed well and was in a good condition. The pattern of length-weight relationship revealed positive allometric growth.

Feasibility of salvaging genetic potential of post-mortem fawns: Production of sperm in testis tissue xenografts from immature donor white-tailed deer (Odocoileus virginianus) in recipient mice

The purpose of this study was to evaluate the long-term outcome of testis tissue xenografting from immature deer. Testis tissue was collected post-mortem from a 2-mo-old white-tailed deer fawn (Odocoileus virginianus) and small fragments of the tissue were grafted under the back skin of immunodeficient recipient mice (n=7 mice; 8 fragments/mouse). Single xenograft samples were removed from representative recipient mice every 2mo from grafting for up to 14mo post-grafting. The retrieved xenografts were evaluated for seminiferous tubular density (per mm2) and tubular diameter, as well as for seminiferous tubular morphology and identification of the most advanced germ cell type present in each tubule cross section. Overall, 63% of the grafted testis fragments were recovered as xenografts. Testis tissue xenografts showed a gradual testicular development starting with tubular expansion by 2mo, presence of spermatocytes by 6mo post-grafting, round and elongated spermatids by 8mo, followed by fully-formed sperm by 12mo post-grafting. The timing of complete spermatogenesis generally corresponded to the reported timing of sexual maturation in white-tailed deer. This study demonstrated, for the first time, that testis tissue xenografting from immature deer donors into recipient mice can successfully result in testicular maturation and development of spermatogenesis in the grafts up to the stage of sperm production. These results may therefore provide a model for salvaging genetic material from immature male white-tailed deer that die before reaching sexual maturity.

Ghrelin attenuates heat-induced degenerative effects in the rat testis

This study was conducted to examine the efficacy of ghrelin in prevention of deleterious effects of heat stress in rat testicular tissue. Forty five adult male rats were scheduled for this study and were divided equally into three groups: heat-saline, heat-ghrelin and control-saline. The scrota of heated-designed rats were immersed once in water bath at 43°C for 15min. Immediately upon heating, 2nmol of ghrelin were given subcutaneously to heat-ghrelin animals every other day up to day 60 and physiological saline to the other two groups using the same method. The animals were sacrificed at 10, 30 and 60days after heat treatment and their testes were taken for later photomicrograph and immunohistochemical analysis. Testicular histopathology revealed a significant reduction in the means of seminiferous tubules and Sertoli cell nucleus diameters as well as germinal epithelium height on day 10 in both heated groups. Furthermore, other testicular components including miotic index, spermatogenesis rate, presence of spermatocytes and volume densities were dramatically decreased following heat exposure. Notably, ghrelin caused a partial recovery in all of the above-mentioned parameters and accelerated testicular regeneration process by day 30 compared to the heat-saline group (P<0.05). Because of testicular progressive recovery, these indices were similar among groups on day 60 (P>0.05). However, immunohistochemistry evaluation for in situ detection of Bcl-2 protein did not exhibit any germ cells—positive of this factor among groups at different experimental days. In conclusion, the results of the present study indicate for the first time the novel evidences of ghrelin ability in attenuation of heat-induced testicular damage and also that ghrelin therapy may be useful as a suppressor of degenerative effects following testicular hyperthermia.

Testicular and ovarian development in the harbour porpoise (Phocoena phocoena)

AbstractTesticular and ovarian development in neonatal and juvenile harbour porpoises Phocoena phocoena was examined, using tissue from animals (males n= 65 and females n= 10) stranded or caught off the coast of England and Wales. Classification of the animals according to their stage of sexual development was undertaken using characteristics of gonadal morphology. Developmental correlates of the immature testis were increased incidence of prespermatogonia in seminiferous tubules, and the increasing proportion of testicular volume occupied by the seminiferous tubules. Using a low magnification (×200) assessment of testis sections, immature specimens could be grouped into three developmentally distinct classes, based on the relative amounts of interstitial and seminiferous tubule tissue and the frequency of prespermatogonia. Adult testes, showing either active spermatogenesis or seasonal quiescence, could be clearly distinguished from immature testes using histological criteria such as the presence of spermatocytes and spermatids. This classification system was used to determine relationships between testicular development and body size: males were classified as immature when they had body lengths &lt; 135 cm and body weights &lt; 30 kg; mature males always exceeded 140 cm in length and 40 kg in weight; and a transitional group, which was regarded as juvenile, had body lengths between 110 and 140 cm and body weights between 20 and 40 kg. Ovarian morphology was used to distinguish neonatal and juvenile females. Neonates displayed characteristic cords of naked ova which dispersed as development progressed. Neonatal animals had body lengths &lt; 100 cm and body weights &lt; 18 kg; within this group (n= 5) there were significant (P &lt; 0.01) left‐right asymmetries in the number of naked ova present, the left ovary containing nearly twice as many ova as the right. Although this difference was not apparent in females with body lengths &gt; 100 cm and body weights between 19 and 30 kg (juveniles) it could be related to the almost total asymmetry of ovulation from the left ovary in this species (Harrison, Brownwell &amp; Boice, 1972).

Colchicine effects on meiosis in the male mouse. I. Meiotic prophase: synaptic arrest, univalents, loss of damaged spermatocytes and a possible checkpoint at pachytene.

Antimitotic agents administered at the time of synapsis (leptotene/zygotene) have been shown to induce synaptic abnormalities visible during pachytene in the male mouse. The object of this study was to test the hypothesis that cells with relatively large amounts of colchicine-induced damage to the synaptonemal complex (SC) are eliminated from prophase whereas cells with relatively small amounts of SC damage proceed through to the end of prophase. Male mice were injected with tritiated thymidine to mark a cohort of spermatocytes at premeiotic S-phase for tracking through pachytene. Forty-eight hours later, when those cells were at leptotene/zygotene, colchicine was administered intratesticularly. Whole-mount SC spreads were made from animals sacrificed at various times following colchicine administration, and prepared for autoradiography. The marked cells were examined by light and electron microscopy and the kind and number of synaptic abnormalities were scored throughout pachytene. Colchicine-induced SC damage included single axial elements (univalents), together with partially synapsed and nonhomologously synapsed SCs. The amount of SC damage (amount and type per cell and frequency of cells with damage) scored at early pachytene exceeded by three- to fivefold the amount at late pachytene. This is consistent with spermatogenic cell loss from the seminiferous tubule via colchicine-induced destruction of Sertoli cell microtubules. The presence of spermatocytes with no more than four autosomal univalents at late pachytene indicates that some cells with low amounts of synaptic damage progress to the end of pachytene. The loss of the most severely damaged cells may represent a meiotic checkpoint at early pachytene in the male mouse.

Pituitary gonadotrophs are strongly activated at the beginning of spermatogenesis in African catfish, Clarias gariepinus.

Pituitary gonadotrophs were studied in male African catfish between 1 and 37 wk of age using antisera against the LH subunits for immunohistological and radioimmunological purposes, and cRNA probes for in situ hybridization. Immunoreactive material was already detectable at the earliest age examined. In juveniles, the signal for the common glycoprotein alpha subunit (GP alpha) was stronger than that for the LH beta subunit. Accordingly, an excess of radioimmunoassayable GP alpha 100 times that of LHbeta was recorded in the pituitary. Using in situ hybridization, the mRNAs were detected 7 (GP alpha) and 13 (LHbeta) wk after hatching. Detection of LHbeta mRNA coincided with a 300-fold increase in the pituitary content of LHbeta and intact LH, whereas GP alpha increased only 15-fold. The number of gonadotrophs per pituitary and the amount of LH per gonadotroph also increased strongly. The strong, initial increase in pituitary LH levels was always associated with the presence of spermatocytes. However, in a limited number of cases (3 out of 12 fish), the pituitary LH content was low despite the presence of spermatocytes. The number of gonadotrophs, the staining intensities (reflecting protein and mRNA), and the pituitary LH content kept increasing, although at a reduced rate, until completion of the first wave of spermatogenesis. In view of the excess of GP alpha over LHbeta, we conclude that expression of the two subunits is regulated in part by different mechanisms, and that expression of LHbeta is rate-limiting for the amount of intact LH. The strong activation of the gonadotrophs shortly after meiosis opens the possibility that a signal of testicular origin stimulates LH expression, in particular its beta subunit. In the absence of a FSH-like gonadotropin in catfish, we propose that LH covers all functions requiring gonadotropic regulation in the African catfish.

Two-stage recovery of gametogenic activity following starvation in Lytechinus variegatus Lamarck (Echinodermata: Echinoidea)

Lytechinus variegatus Lamarck were starved for 28 days and then fed ad libitum for 32 days. Gonadal indices increased significantly with feeding by 9.6-fold in females, and 3.03-fold in males, with most of the growth occurring 8 days after feeding. Histological examination of the ovaries after starvation revealed the presence of oocytes (mean = 61 μm) but no visible germinal epithelium. The size of these oocytes increased significantly within the first 8 days of feeding. Ovarian tubules developed a visible germinal epithelium between 8 and 16 days of feeding. The mean oocyte diameter continued increasing to 32 days of feeding (mean = 90 μm). Histological examination of the testicular tubules after starvation revealed the presence of spermatocytes and spermatids, and some mature spermatozoa, but no germinal epithelium was visible. These spermatocytes and spermatids differentiated within the first 8 days of feeding to mature spermatozoa. The testicular tubules developed thin, discontinuous patches of germinal epithelium between 8 and 16 days of feeding. Continuous zones of germinal epithelium occurred in the testes by 32 days of feeding. This suggests that both sexes utilize a two-stage strategy of gametogenic recovery after starvation. First, an immediate completion of development and/or differentiation of existing gametes would allow individuals to attain some reproductive capacity if limited food supplies are found after a period of nutrient deprivation. Second, subsequent initiation of gametogenesis to produce a new cohort of gametes would allow individuals to maximize reproductive output.

Heterochromatization and euchromatization of whole genomes in scale insects (Coccoidea: Homoptera)

In several families of scale insects (coccids), the sex of an embryo is determined by the number of genetically active genomes present (one = males, two = females). In mealybugs (Pseudococcidae), both males and females develop from fertilized eggs but, in the embryos that develop into males, the set of chromosomes (genome) of paternal origin (PG) becomes heterochromatic (H) and genetically inactive and is not transmitted to the offspring. The mechanism that reduces the number of active genomes in male embryos may vary between families and even between congeneric species. Thus, in male embryos of most armored scale species (Diaspididae), the PG is eliminated, while in a few species it becomes H. In two genera of soft scales (Coccidae), males develop from unfertilized eggs when one of two identical genomes of maternal origin becomes H. In most male tissues, one genome remains H. However, in several tissues that become polyploid by endoreduplication, the PG becomes E and genetically active. The tissues in which the PG becomes E often vary between species and the analysis of hybrid males demonstrated that whether the PG becomes H or remains E is determined by the genome of maternal origin. The euchromatization of the PG in the haploid sector of mosaic male embryos and the presence of spermatocytes with two E genomes (instead of one E and one H), following the irradiation of young mealybug males, strongly suggest that the maintenance of the H state requires the presence of a genetically active genome.

Cytological effects of J2581 (5-ethoxy-6-ethoxy-6-[4-methoxyphenyl] methyl-1,3-benzodioxole) on spermatogenesis in the oriental fruit fly, Dacus dorsalis hendel

1. Examination by phase-contrast microscopy of testes from J2581-treated flies showed (1) the presence of spermatocytes and the absence of normal meiotic divisions, and (2) abnormal development of spermatids and sperm bundles. 2. Examination by electron microscopy of flagella from spermatozoa of J2581-treated flies revealed abnormal development of axonemes. 3. Possible interference in microtubule assembly by J2581 is discussed.