Morphology of the reproductive tract and acquisition of sexual maturity in males of Potamotrygon magdalenae (Elasmobranchii: Potamotrygonidae)

The purpose of this study was to describe the structure of the reproductive tract of males of Potamotrygon magdalenae before, during, and after they acquire sexual maturity, and to establish the first maturity scale for males within the family Potamotrygonidae. The male reproductive tract of P. magdalenae is composed of testes, efferent ducts, epididymides, deferent ducts, seminal vesicles, Leydig, alkaline, and clasper glands, and claspers, all of which are paired and functional. Four sexual maturity stages were established: immature, maturing, reproductively active, and resting. The degree of claspers calcification is also a good indicator of sexual maturity in this species. The testes are lobulated, each lobe contains numerous spermatocysts which are organized in zones and are displaced radially from germinal papillae to the spermatozoa zone where individual spermatozoa are conveyed to the efferent ducts. The epididymis can be regionalized in head, body, and tail; these regions are distinguished by external pigmentation and by the epithelium lining configuration. The tail of the epididymis is connected with the deferent duct and this, in turn, with the seminal vesicle. The spermatozoa are organized in spermatozeugmata which begin to form in the deferent duct; this latter organ is attached laterally at the Leydig gland that is composed by simple glandular units. Irregular and vesicular secretions can be found in the genital ducts. These secretions might be associated with the maturation of the spermatozoa and formation of spermatozeugmata. The male reproductive tract of P. magdalenae is similar to other elasmobranchs; however, two types of primary spermatogonia, an epididymis internally regionalized, and the presence and structure of spermatozeugmata are specific features not yet described in freshwater stingrays. Most of the year, the males were reproductively active, however, few resting adult males occurred during one of the months of the lowest waters. J. Morphol. 276:273–289, 2015. © 2014 Wiley Periodicals, Inc.     

Correlated Responses in Male Reproductive Traits in Mice Selected for Litter Size and Body Weight

Correlated responses in male reproductive traits were determined at 4, 6 and 8 weeks of age in lines of mice selected for large litter size (L⁺), large 6-week body weight (W⁺), large litter size and small body weight (L⁺W^-) and small litter size and large body weight (L^-W⁺), and in an unselected control (K). Concentration of serum testosterone and weights of testes, seminal vesicles, epididymides and adrenal glands increased with age. Line differences in testosterone concentration were not detected. L⁺ and W⁺ males exhibited positive correlated responses in testes, epididymides and seminal vescile weights. Testis weight adjusted for body weight was significantly larger for L⁺ than controls and approached significance for W⁺. Realized genetic correlation betestis weight and litter size was 0.60 ± 0.04, and the realized partial genetic correlation holding body weight constant was 0.42. Therefore, pleiotropic loci, acting via the hypothalamic-pituitary axis, affect testis weight and litter size independently of body weight. Additionally, genes influencing overall growth have a pleiotropic effect on testis weight and litter size in mice; the realized genetic correlations of body weight with testis weight and with litter size were 0.60 ± 0.03 and 0.52 ± 0.10. Testis weight increased in both L⁺W^- and L^-W⁺ males. The positive correlated response in L⁺W^- may have resulted from changes in frequency of genes controlling reproductive processes; whereas, in L^-W⁺ it could have been the result of changes in the frequency of genes associated with body weight.     

Gonadal and hormonal characteristics of captive adult mourning doves during the nesting cycle

Paired mourning doves ($\text{Zenaida}$$\text{macroura}$) of a captive breeding colony were selected and sacrificed on specific day intervals postlaying and posthatching during 1976–1977. Blood plasma samples were analyzed for androgens, estradiol, and progestins using radioimmunoassays. Testes, ovary and oviduct weights, spermatozoan numbers, diameter of the three largest follicles in the ovary, the presence or absence of eggs in the reproductive tract, and crop gland characteristics also were recorded. Differences (P<0.05) existed between nonbreeding and breeding pairs in testes weights, spermatozoan numbers, and ovary and oviduct weights. No distinct cyclic pattern was observed in gonadal variables among breeding males and females during the nesting cycle, although trends were observed. No differences (P > 0.05) in androgen and progestin concentrations in males, or estradiol and progestin concentrations in females, between nonbreeding and breeding pairs, or among breeding pairs during different stages of the nesting cycle, were observed. Analysis of reproductive variables by stage of crop gland activity tended to indicate an inverse relationship between gonadal and crop gland activity in both male and female doves during the nesting cycle.     

Effects of chemical occlusion of vas deferens on the reproductive organs in gerbil Meriones hurrianae Jerdon.

Male gerbils were sterilized by giving a single injection of a sclerosing chemicial (5% KMnOH) directly into the vasa. After 3 weeks the gerbils were killed. Testes, accessory sex organs, and thyroid and adrenal glands were removed and weighed. Halves of testis and epididymides were fixed in Bouin's fluid fo r microscopic study. The remaining halves were frozen and total RNA, protein, sialic acid, seminal vasicular fructose, and testicular lipids were later determined. Cholesterol estimations were also made. 2 weeks following vas injections animals were tested by exposing them to cycling estrous females. 21 days later the females were examined for possible implantation sites. It was shown that the males had been sterile. Weights of testicles, accessory sex organs, thyroid and adrenal gland remained normal, except that there was a significant increase in the weight of the ventral prostate. No histological changes were found in the testes. Protein content of the testes, epididymides, and seminal vesicles did not change. A decrease in RNA was noted. Sialic acid levels did not alter. Cholesterol and total lipids were normal. Alkaline phosphatase activity in the testes and epididymides had not changed after 3 weeks. Vasicular fructose was normal. Complete occlusion of the vasa resulted. After 100 days there was no return to fertility. The results appear to be permanent.     

Adverse effects of rosemary (Rosmarinus officinalis L.) on reproductive function in adult male rats

Ingestion of rosemary (Rosmarinus officinalis L.) by two groups of adult Sprague-Dawley rats at levels of 250 and 500 mg/kg body wt for 63 days was investigated for its effects on fertility. Body weight and absolute and relative testes weights were not affected, but the average weights of epididymides, ventral prostates, seminal vesicles, and preputial glands decreased significantly. A significant decline in spermatogenesis in testes due to a decrease in the number of primary and secondary spermatocytes and spermatids in treatment group 2 (500 mg/kg) is attributed to a significant decrease in testosterone. Sperm motility and density were also significantly decreased in the cauda epididymis and in the testes of rosemary-treated male rats in group 2. In addition, the treatment markedly increased the number of fetal resorptions in female rats impregnated by group 2 males, thereby reducing their fertility.     

Critical window of male reproductive tract development in rats following gestational exposure to di-n-butyl phthalate

BACKGROUND: Gestational exposure to di-n-butyl phthalate (DBP), a ubiquitous environmental contaminant, has been shown to interfere with the development of the male reproductive tract by acting as an antiandrogen. This study was conducted to identify the critical days for the abnormal development of the male reproductive tract, specifically the testis and epididymis. METHODS: Timed-pregnant Sprague-Dawley rats were dosed with DBP at 500 mg/kg/day on gestation day (GD) 14 and 15, 15 and 16, 16 and 17, 17 and 18, 18 and 19, or 19 and 20 (GD 0=plug day). Anogenital distance (AGD) was measured on postnatal day (PND) 1 and 13, while areloa number was recorded on PND 13 only. After weaning, males were allowed to mature to PND 90 at which time they were necropsied. Areloa number and AGD were recorded and testes, epididymides, seminal vesicles, prostate gland, kidneys, and liver weighed. Blood serum was collected and assayed for total testosterone concentration. RESULTS: There were no observable effects on litter size, sex ratio, serum testosterone concentration, or mortality of pups. Statistically significant permanent reductions in AGD were seen in males exposed prenatally to DBP on GD 15 and 16 or GD 18 and 19. On PND 13, areola were present in males exposed to DBP on GD 15 and 16, 16 and 17, 17 and 18, and 19 and 20. However, permanent retention occurred only in males after DBP exposure on GD 16 and 17. Exposure to DBP on only GD 17 and 18 elicited a reduction in epididymal weights; while exposure on only GD 16 and 17 caused a significant increase in the weights of the testes due to edema. In this study, epididymal and testicular malformations were most prevalent after exposure to DBP on any gestational day. Epididymal malformations, characterized by agenesis of various regions and small or flaccid testes were significantly increased in DBP-exposed males only on GD 16 and 17. CONCLUSIONS: These findings suggest that 2-day DBP exposure is highly detrimental to the developing reproductive tract of the male fetus and the critical window for abnormal development is GD 16-18.     

Size Dependent Male Reproductive Tactic in the Two-Spotted Goby (Gobiusculus flavescens)

Male investment in testes and sperm duct gland in the polygamous nest breeding two-spotted goby Gobiusculus flavescens (Fabricius) was investigated in relation to time in reproductive season and individual physical parameters. This small teleost fish is most likely the most abundant species found along the rocky shores of the North East Atlantic. The two-spotted goby has a single reproductive season, during which nest-caring males can raise several clutches of offspring. According to the literature the males are on average larger than the females. Here we report for the first time a population showing a reversal of this trend, with males on average being smaller than females, a difference likely caused by a large proportion of small males. Early in the breeding season these small males have typical sneaker characters, with relatively large testes and small seminal duct glands compared to the larger dominant territorial males. The presence of these two alternative male reproductive tactics is confirmed by histological studies, which shows the presence of sperm in the sperm duct glands (SDG) of smaller males, but not in the SDG of intermediate and larger males. To our knowledge, males with typical sneaker characters have not been reported in earlier studied populations of two-spotted goby. Interestingly we found that testes investment declined significantly over the course of the breeding season, and that this reduction was significantly more pronounced in small compared to the large males. Further, a significant increase in seminal duct gland (SDG) mass was observed for the smaller males over the breeding season. We propose that this indicates a possible shift in mating tactic by smaller males from a parasitic to a nest-holding tactic over the course of the breeding season. Thus, the observed size dependent plasticity in investment in SDG over time suggests that the reproductive tactic of G. flavescens is conditional, and possibly influenced by mate availability and male—male competition.     

Seasonal timing of sperm production in roe deer: interrelationship among changes in ejaculate parameters,morphology and function of testis and accessory glands

Roe deer are seasonal breeders with a short rutting season from mid-July to mid-August. The seasonality of reproductive activity in males is associated with cyclic changes between growth and involution of both testes and the accessory sex glands. This study characterizes morphological and functional parameters of these organs prior to, during and after breeding season in live adult roe deer bucks. Size and morphology of the reproductive tract was monitored monthly by transcutaneous (testes, epididymis) and transrectal (accessory glands) ultrasonography. Semen was collected by electroejaculation. Concentration, motility and morphological integrity of spermatozoa as well as the content of proteins and testosterone in semen plasma were evaluated. Proportions of haploid, diploid and tetraploid cells were estimated by flow cytometry in testicular tissue biopsies. Serum testosterone was measured by enzyme immunoassay. Most parts of the male reproductive tract showed distinct circannual changes in size and texture. These changes were most pronounced in the testes, seminal vesicles, and prostate. All reproductive organs were highly developed during the rut only. The volume of ejaculates, total sperm number and percentages of motile and intact spermatozoa also showed a maximum during this period and corresponded with high proportions of haploid cells in the testis. The highest percentages of tetraploid cells were found in the prerutting period. The production of motile and intact spermatozoa correlated with both the protein content of semen plasma and the concentration of testosterone in semen plasma and blood serum. These results suggest the importance of combined actions of the testes and accessory sex glands and the crucial role of testosterone in facilitating the optimal timing of intensified semen production to ensure sufficient numbers of normal spermatozoa in seasonal breeders.     

Mating senescence and male reproductive organ size in the Mexican fruit fly

Ageing can reduce the probability that individuals reproduce. The present study investigates whether ageing influences the mating frequency of mass‐reared fertile and sterile Mexican fruit flies Anastrepha ludens (Loew). The ability of males of different ages to inhibit female remating is also determined, and the growth of male reproductive organs is measured as they age. Young males (6 days old) have a lower mating frequency than older males, and also have a lower capacity to inhibit female remating than older males. However, 7‐day‐old males are as likely to inhibit female remating as older males. Young males also have smaller reproductive organs than middle‐aged (21‐day‐old) or senescent males (57‐day‐old). These results have implications for the sterile insect technique because sterilized males of A. ludens are released in the field 6 days after emergence. The highest mating frequency, the lowest mating latency and the largest size of testes are observed at 21 days of age. Older males (57 days old) have more sperm in their seminal vesicles than young males (6 and 9 days old). Accessory glands take longer to grow to their complete size compared with testes, and mating frequency is more closely associated with accessory gland size than testes size. Furthermore, there are more sperm in the seminal vesicles during the afternoon period of peak sexual activity than during the morning when sexual activity is absent. These results indicate that, even at the onset of reproductive senescence, mass‐reared males of A. ludens are still capable of mating, as well as inhibiting remating in females.     

The influence of photoperiod on growth and sexual function in male and female collared lemmings (Dicrostonyx groenlandicus).

The effect of photoperiod on sexual function and growth in weanling male and female collared lemmings (Dicrostonyx groenlandicus) was studied. Males and females maintained in 6 hr light:18 hr dark after weaning were larger at the end of 70 days than their siblings kept in 20L:4D. Males in 6L:18D were longer and overall body growth was greater. Males in 6L:18D had heavier adrenals but there were no differences in the weights of testes, preputial glands or seminal vesicles or in the mean testosterone levels of the two groups. Females in 6L:18D had heavier preputial glands than the 20L:4D females. There were no differences between the two groups in uterine, ovarian or adrenal weights or in the number or mean size of atretic or healthy Graafian follicles. Adult males kept in 6L:18D increased more in body weight than those in 20L:4D, but there was no detectable influence of the short photoperiod on reproductive function.     

Effect of feed restriction on Hershberger and pubertal male assay endpoints

BACKGROUND: The Hershberger and male pubertal onset assays have been identified as possible Tier I screening tests to detect endocrine‐active compounds (EACs). Both tests rely on changes in reproductive and/or accessory sex gland (ASG) weights in young animals. Because chemical treatment may affect growth rate, the relationship between body weight and reproductive/ASG weights was examined using feed restriction (FR) to produce a targeted 10% decrease in body weight. METHODS: In the male pubertal onset assay, 23‐day‐old rats (12/group) were given ad lib feed or FR until euthanized at 45, 49, 52, 56, or 59 days of age. Despite a 10% body weight differential, pubertal onset was not significantly delayed and testes weights were conserved. Absolute prostate, ventral prostate, seminal vesicle, epididymides, and liver weights were decreased by FR. Relative weights for the prostate, ventral prostate, and seminal vesicles were similar to controls, but relative epididymides and liver weights still exhibited FR‐mediated changes. In the Hershberger assay, male rats (12/group) castrated at 36 days of age were given ad lib feed or FR in the presence or absence of testosterone propionate (T) from 46–55, 50–59, or 56–65 days of age. At 56, 60, and 66 days of age, rats were euthanized. In untreated animals, FR did not alter absolute ventral prostate, seminal vesicles, or Cowper's gland weights; however, absolute and relative weights of the levator ani‐bulbocavernosus muscles (LABC) were affected. In T‐treated animals, absolute organ weights (the ventral prostate, seminal vesicles, LABC, and glans penis) were relatively insensitive to FR. The weight of the Cowper's gland was affected only at 66 days of age. RESULTS: These data show that reproductive and ASG organ weight endpoints in the Hershberger and male pubertal onset assays can be influenced by FR levels that produce a 10% change in terminal body weight. CONCLUSIONS: The establishment of objective criteria for a positive or negative result is problematic due to the confounding effects of body weight on some endpoints. Furthermore, a 10% decrease in body weight seems to be excessive as a requirement for high‐dose toxicity in these assays due to possible indictment of agents that are not EACs, as well as potential masking of EAC effects coincident with body weight changes. Minimally, caution must be used in interpreting assay results in the presence of a 10% body weight change, recognizing the possible confounding effects of this degree of growth suppression. Birth Defects Res B 68:363–374, 2003. © 2003 Wiley‐Liss, Inc.     

Sexual selection affects the sizes of the mammalian prostate gland and seminal vesicles

The accessory reproductive glands of male mammals contribute the bulk of the secretions in which spermatozoa are transported to the female tract during copulation. Despite their morphological diversity,and the chemical complexity of their products,little is known about the possible effects of sexual selection upon these glands in mammals. Here we consider the seminal vesicles and prostate glands in a sample of 89 species and 60 genera representing 8 Orders of mammals. The sizes of the accessory glands are analysed in relation to body weight and testes weight. Both the seminal vesicles size and prostate size (corrected for body weight) correlate positively with relative testes size in this sample; this finding remains highly significant after application of procedures to correct for possible phylogenetic biases in the data set. The accessory reproductive glands are also significantly larger in those mammals which have large relative testes sizes,and in which the likelihood of sperm competition is greatest. These results support the hypothesis that sexual selection has played an important role in the evolution of the mammalian prostate gland and seminal vesicles.     

Effects of treatment of male and female rats in infancy with mifepristone on reproductive function in adulthood

Treatment of neonatal male and female rats with mifepristone (1 mg s.c. every 2 days from Day 1 to 15 or Day 4 to 18 of life) interfered with the normal development of their reproductive capacities and of the adrenal glands. The effect on the adrenal glands seemed only temporary. Effects on reproductive functions seemed permanent. Female rats developed abnormalities in structure of the oviduct and ovarian capsule reminiscent of effects reported after perinatal treatment with androgen or oestrogen. During adulthood, anovulatory polyfollicular ovaries developed, reminiscent of rats treated with a small dose of androgen in infancy. Males showed retardation of testicular growth and delay of puberty. During adulthood testes did not grow beyond 65% that of normal rats. Sexual behaviour was deficient in that ejaculations occurred only rarely; when ejaculations did occur, fertility was unimpaired. Males treated with mifepristone in infancy exhibited female sexual behaviour as adults after castration and injections of testosterone and oestradiol. All effects pointed to an insufficient action of testicular hormones in infancy to bring about normal 'masculinization'. Mifepristone therefore appears to show 'teratogenic' actions in rats which affect female reproductive tract development and, in males and females, development of the systems underlying normal reproductive activity and functions in adulthood.     

Reproductive biology of the male Cape porcupine, Hystrix africaeaustralis

The reproductive tract of the male Cape porcupine is morphologically and histologically similar to that of New World hystricomorph rodents. Males are reproductively active throughout the year and attained sexual maturity (complete spermatogenesis) at an age of 8-18 months. Testes weight, epididymides weight and seminiferous tubule diameter attained asymptotic values at the age of 23-30 months. A tendency towards seasonality in the activity of accessory glands, preceded and accompanied by an increase in circulating plasma testosterone values, may be considered as a factor enforcing seasonal breeding in females. Testosterone concentrations in pubertal males were significantly higher than those recorded in sexually mature males.     

Male accessory sex glands produce heparin-binding proteins that bind to cauda epididymal spermatozoa and are testosterone dependent

Heparin binds to bovine sperm and stimulates capacitation in vitro. Seminal plasma alters the ability of epididymal sperm to bind heparin, and several heparin-binding proteins (HBPs) have been identified in bull seminal plasma. This study had three objectives: 1) to identify production sites of seminal plasma HBPs, 2) to determine which HBPs bound to cauda epididymal sperm, and 3) to determine whether presence of HBPs was testosterone dependent. Proteins from bull or rat seminal vesicles, prostates, and bulbourethral glands were separated by heparin affinity high-performance liquid chromatography. HBPs were found in all accessory glands of rats and bulls, but the major source of bovine seminal plasma HBPs appeared to be seminal vesicles. Between 25% and 50% of the protein from each gland bound to the heparin column, and NaCl concentrations required to elute proteins ranged from 0.15 to 1.4 M. One-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that major HBPs were relatively small, with molecular weights between 13 and 31 kDa, but some HBPs also exhibited higher molecular weights, between 40 and 100 kDa. Radioiodinated HBPs from each bovine gland were incubated with epididymal sperm. Labeled HBPs binding to sperm exhibited molecular weights of 14, 16, 24, and 30 kDa as determined by SDS-PAGE and autoradiography. The HBP content of the accessory sex glands decreased significantly in castrated rats and was restored to levels of sham-operated controls by testosterone replacement. Heparin-binding proteins may play a role in fertilization by attaching to sperm surfaces, enabling heparin-like glycosaminoglycans in the female reproductive tract to induce capacitation.     

Inhibitory effects of technical grade methoxychlor on development of neonatal male mouse reproductive organs

Effects of technical grade methoxychlor (MX), an estrogenic insecticide, and 17 beta-estradiol (E2) were examined on serum testosterone (T) concentrations and growth and histology of neonatal male mouse reproductive organs. Male NIH/Swiss mice received i.p. injections daily from birth to Day 9 with one of the following: 10 micrograms E2 or 0.1 or 1.0 mg MX or sesame oil vehicle. The mice were killed on Day 10. MX or did not affect body weights or mortality. Serum T concentrations in control mice were 0.29 +/- 0.03 ng/ml; T concentrations in males treated with MX or E2 were reduced. The 1.0-mg dose of both MX and E2 significantly decreased DNA contents of the seminal vesicles (SV), bulbourethral glands (BUG), and ventral prostate (VP) compared to controls. In the same animals, DNA contents of testes, epididymides, and efferent ductules were not decreased. The lower dose of MX (0.1 mg) decreased DNA content of only BUG and SV. DNA content of the ductus deferens was not affected by any treatment. E2 and both doses of MX also decreased epithelial morphogenesis in the SV and BUG, and inhibited the onset of mucin production in BUG epithelium and smooth muscle differentiation in the ductus deferens. In summary, our results indicate that technical grade MX, at doses as low as 0.1 mg/day, and E2 inhibit neonatal male reproductive tract development and decrease serum T concentrations.     

Eversible abdominal vesicles and some observations of the male reproductive system of the spoon wing lacewing Palmipenna (Neuroptera: Nemopteridae)

The anatomy and histology of the abdominal eversible vesicles and the male reproductive tract of the spoonwing lacewing Palmipenna (Neuroptera: Nemopteridae) have been examined. The eversible vesicles open as a pair of large bulbous sacs between tergites five and six, each folding into halves during retraction. They consist of highly pleated cuticle, beneath which are typical gland cells, each having a circular or oval end apparatus surrounded by closely packed microvilli. These communicate to the surface via cuticularized channels. In spite of considerable behavioral observations, male Palmipenna were never noted with everted vesicles. Even during mating trials, where females were presented to males in the field, the vesicles were never everted during the attempted copulation that ensued. Our observations indicate that mate attraction is mediated by the release of a female pheromone. The function of the eversible vesicles and their associated gland cells remains unknown, and their structure appears to be unique to the Nemopteridae. The reproductive tract is similar to that of other Neuroptera, consisting of a pair of five-lobed testes, a medium-to-large pair of seminal vesicles, and three pairs of accessory glands. The major accessory glands are surrounded by circular and longitudinal muscle, and are lined by an epithelium, the cells of which presumably secrete the amorphous rods of material always present in this pair of glands. The sperm in the seminal vesicles are elongate, with a pointed head and a 9 + 9 + 2 configuration in the flagellum. A single spermatophore, similar in shape to that described for other Neuroptera, was found occluding the bursa copulatrix of a teneral female. © 1994 Wiley-Liss, Inc.     

Effects of age and photoperiod on reproduction and the spleen in the marsh rice rat (Oryzomys palustris)

To examine the interactions between age and photoperiod on reproduction and spleen weights, we exposed adult male and female rice rats of various ages to photoperiods of 16:8-h light-dark photoperiods (16L:8D) or 12L:12D. After 10 wk, animals were killed and the following data were recorded: weights of testes, seminal vesicles, uterus, ovaries, body, and spleen and, in addition, vaginal patency. Young adult males displayed a greater degree of testicular and seminal vesicle regression in short photoperiods than did older males; the testes of most older males did not regress in response to short photoperiods. Spleen weight was unresponsive to short photoperiods in all males, but was affected by age. Females, however, exhibited reproductive organ regression and decreased vaginal patency in response to short photoperiods at all ages examined. Body weights were affected by photoperiod in young females, and, as in males, photoperiod had no effect on spleen weights. These data suggest that the reproductive response to photoperiod in adult male rice rats declines with age, whereas in adult females it does not.     

Effects of Malva viscus conzattii Greenm flower extract on testicular function of the house rat Rattus rattus Rufescens & the gerbil Meriones hurrianae Jerdon: a biochemical study

Extract of the flower Malva viscus conzattii (M. conzattii) was administered at a dose of 25/50 mg/day/animal to 30 healthy adult male gerbils and 30 adult male house rats to determine its effect on fertility. After 25 days' treatment fin l body weight, and the weights of testes, epididymides, seminal vesicles, and adrenal glands were measured. Testis, epididymides, and seminal vesicles were prepared for histological examination and total protein, RNA, sialic acid, and alkaline phosphatase activity were determined. Quantitative estimation of cholesterol was also made. While overall body weight remained stable during treatment, testicular weight in both animals was drastically decreased. A complete spermatogenic arrest in the testes was evident in house rats treated with 50 mg/day for 20 days and in the gerbil treated with 25 mg/day for 25 days. The seminiferous tubules showed marked degeneration, lined by 1 or 2 cell layers. Epididymides showed degenerative changes as well. RNA contents of the testes, epididydmides, and seminal vesicles of treated anials were significantly lowered as was sialilc acid content. Total cholesterol was increased significantly. M. conzattii causes an effective inhibition of spermatogenesis in gerbils and house rats in 25 states and induces infertility.     

Virilization of the male pouch young of the tammar wallaby does not appear to be mediated by plasma testosterone or dihydrotestosterone.

Virilization of the male urogenital tract of all mammals, including marsupials, is mediated by androgenic hormones secreted by the testes. We have previously demonstrated profound sexual dimorphism in the concentrations of gonadal androgens in pouch young of the tammar wallaby Macropus eugenii during the interval when the urogenital sinus virilizes. To provide insight into the mechanisms by which androgens are transported from the testes to the target tissues, we measured testosterone and dihydrotestosterone in plasma pools from tammar pouch young from the day of birth to Day 150. Plasma testosterone levels were measurable (0.5-2 ng/ml) at all times studied, but there were no differences between males and females. These low concentrations of plasma testosterone appear to be derived from the adrenal glands and not the testes. Plasma dihydrotestosterone levels in plasma pools from these animals were also low and not sexually dimorphic. We conclude that virilization of the male urogenital tract cannot be explained by the usual transport of testosterone or dihydrotestosterone in plasma but may be mediated by the direct delivery of androgens to the urogenital tract via the Wolffian ducts. Alternatively, circulating prohormones may be converted to androgens in target tissues.