Postnatal development of the testes in the cuis, Galea musteloides

Abstract

SummaryTesticular development to 9 months of age has been studied. Seminiferous tubule diameter increased in a linear manner between 13 and 65 days of age, and there was a steep increase in testicular weight with age. At about 9 months the animals weighed 400-500 g and total testicular weight was about 10 g. This relatively large testicular size was correlated with high sperm density in the semen.Spermatogenesis commenced at about 21-25 days of age, when the first spermatids were found. Spermatozoa appeared in a small proportion of seminiferous tubules by 31-35 days of age, and were seen in the epididymides of an animal of 31 and another of 34 days. Epididymal spermatozoa were consistently present in large numbers after 60 days and this correlated with the increased frequency of mature seminiferous tubules.Leydig cell size increased rapidly from 13 to about 60 days, then remained constant. Inferences have been drawn from this and the study of spermatogenesis about the level of testosterone secretion.The results indicate that the male cuis is almost fully grown and sexually mature by about 90 days of age.The cuis, Galea musteloides, a hystricomorph rodent bearing some similarities to the laboratory guineapig, was introduced as a laboratory animal by Weir (1970), who described techniques of management and breeding. Subsequent studies on the reproduction of this species have been almost exclusively directed towards the female and have resulted in the establishment of the length of the oestrous cycle, gestation period and the effects of season on breeding performance (Rood & Weir, 1970). Weir (1971) also found that the occurrence of the oestrous cycle could be influenced by the presence of a male. No systematic studies of the male cuis have yet been carried out, so that information is lacking on such basic matters as the age at which puberty occurs and full sexual maturity is reached. The present investigation of postnatal testicular development has been undertaken to remedy this situation. Data have been collected on the changes with age in body and testicular weights, seminiferous tubule diameter and Leydig cell size in young cuis. These parameters are correlated with the onset of spermatogenesis, determined by a quantitative analysis of cell associations in the seminiferous tubules and observation of the presence of spermatozoa in the epididymis. Materials and methodsA total of 109 male cuis aged from 13 days to 9 months, taken from the Wellcome Institute breeding colony, was killed at intervals over a period of 3 years. An uninterrupted series was obtained between 13 and 65 days, but it was not possible to extend this continuously to an age much beyond that of full sexual maturity. However, a group of 8 animals of 89-94 days, and another of 6 animals aged about 8-9 months, were obtained. After death, the animals were weighed. The testes and epididymides were removed, fixed in Bouin's fluid for 24 hours (an incision being made after 1 hour), and then transferred to 70% alcohol. The epididymides were separated and...

Tissue-specific epigenetic inheritance after paternal heat exposure in male wild guinea pigs

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Environmental Change-Dependent Inherited Epigenetic Response

“…For each experiment, five F0 males (but no females) were exposed to either a change in diet (“experiment D”, see below) or to an elevated ambient temperature (“experiment H”, see below) for 62 days. The length of this period reflects a full cycle of spermatogenesis in guinea pigs [30,31]. In both of the experiments, each male was mated twice with two females, once before and once after the change in the environmental factor, and livers (Ls) of F1 sons (F1Ls) were harvested at 7 days of age.…”

Maturation of Epididymal Spermatozoa in the Nondomesticated Guinea Pigs Cavia aperea and Galea musteloides

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