We have examined the effects of ageing on the increase in apoptotic cells numbers in the male genital tract of the house mouse (Mus musculus). We have found that not all organs have the same response. There is an induction of apoptosis in both the epididymis and ventral prostate. However, seminal vesicles and other prostatic lobes remain unaffected. Apoptosis was assessed by several methods: TUNEL, detection of the active fragment of caspase-3 and the pattern of DNA fragmentation on agarose gels. This increase in apoptosis is related to the fall in testosterone levels, although there is only a partial decrease in androgen receptor (AR). AR is still present in all tissues and only moderately reduced in the epididymis and ventral prostate. A more intense increase of lipofuscin granules, which may be indicative of oxidative stress, occurred in these tissues. Finally, testosterone supplementation reverses the changes (both in apoptosis and lipofuscin content in the tissue), suggesting a role of androgens in these processes.

It is widely accepted that temperature regulates gene expression and function in the epididymis. However, the significance of reduced temperature of

Summary: The aim of this study was to identify some details of the changes induced by a short‐day light regime (8:16 light:dark) on the male genital tract and accessory sex glands of the golden hamster Mesocricetus auratus. We principally examined the presence of apoptotic cells in the epithelium from different regions of the epididymis, seminal vesicles, prostate and coagulating gland. We detected an increase in the percentage of apoptotic cells in situ using the TUNEL technique in animals that were maintained for 6, 8 or 12 weeks in a short photoperiod. That those cells were indeed undergoing apoptosis was confirmed by the immunodetection of the active fragment of caspase‐3. The apoptotic indices in the different tissues analysed were low, but were maintained for weeks, suggesting cell loss at a steady rate. We tried to correlate these changes with the testosterone levels in serum as well as with the oxidative stress in the tissue. On the other hand, the increase in size and number of lipofuscin granules indicated the possibility that a parallel increase in oxidative stress occurred in the tissues. The normalization in the number of apoptotic cells and lipofuscin granules in animals treated with testosterone suggests that both phenomena might be related to changes in the hormone levels.

Spermatogenesis is a series of events that constitute programmed cell differentiation, with dramatic changes in morphology, biochemistry and gene expression which are regulated by temporal and especially endocrine, paracrine and autocrine mechanisms. During the various stages of spermatogenesis and particularly during the differentiation of spermatids, there is massive degradation of cytosolic proteins, nuclear and membrane due to the elimination of much of the cytoplasm which has round spermatid. This protein degradation occurs within the seminiferous epithelium and is mediated by cellular systems described for this purpose. The proteasome is a multienzyme complex responsible for degrading the majority of nuclear and cytosolic proteins, after they are marked for destruction by covalent attachment of ubiquitin molecules. This selective destruction of cellular proteins is a key mechanism in the process of spermatogenesis. This article discusses the basics of male gonadal physiological process and the current understanding of the role of the ubiquitin proteasome system in the functional maintenance of spermatogenesis are reviewed.