Seasonal changes in testicular structure and function in the blue fox (Alopex lagopus), as quantified by morphometric analysis and measurement of adenylate cyclase activity

Abstract

The volume of the blue fox testis showed 5-fold changes during the year, associated with considerable changes in cellular composition. The seminiferous epithelium was maximally regressed in August, when 94% of tubules contained only spermatogonia. By late October, approximately 6 months before the mating season, 40% of tubules contained primary spermatocytes. From the middle of January until the end of April all tubules contained spermatids or more advanced haploid cells. Tubular diameter increased by 73% during testicular re-development, and epithelial height increased 3-fold. Regression to the basal state occurred during May to July. The volume densities of the seminiferous epithelium and of interstitial tissue remained approximately constant throughout the year. Soluble Mn2+-dependent adenylate cyclase activity showed seasonal variations that paralleled those of the haploid germ cell population and testicular volume, whereas somatic cell adenylate cyclase activity was relatively constant.

Effect of Refractoriness to Long Photoperiod on Sperm Production and Quality in Tomcats

“…In some short‐day breeders like the male silver and blue fox, short days are necessary if gonadal stimulation is to occur (Smith et al. , ; Forsberg et al. ).…”

“…Likewise, photorefractoriness has been reported in short-day breeders too. In some short-day breeders like the male silver and blue fox, short days are necessary if gonadal stimulation is to occur (Smith et al 1984(Smith et al , 1986Forsberg et al 1989). However, male silver fox show testicular regression after 1 year of SP (Forsberg et al 1989).…”

Preliminary studies of the effects of bromocriptine on testicular regression and the spring moult in a seasonal breeder, the male blue fox (Alopex lagopus)

“…The normal seasonal variations in the occurrence of these categories in both immature and adult males have been described elsewhere (Smith et al, 1986(Smith et al, , 1987b. Examination offur.…”

“…The male blue fox (Alopex lagopus) is a seasonal breeder, with 5-fold annual changes in testicular size and associated seasonal changes in blood concentrations of a range of hormones (Smith et al, , 1986. These variations are probably influenced by seasonal changes in environmental cues such as daylength and temperature, but little is known about the neuroendocrine mechanisms that mediate these cues.…”

Photoperiodic regulation of reproduction in the male silver fox (Vulpes vulpes)

“…The most striking result was the low (P < 0-01) post-thaw motility of the semen frozen in June. (Smith et al, 1984(Smith et al, , 1985(Smith et al, , 1986(Smith et al, , 1987, which are also short-day breeders. Furthermore, our experiments show that short days not only stimulate redevelopment of the testes but can also inhibit testicular regression.…”