Apoptosis and proliferation in the testes of the brown hare ( Lepus europaeus ) under the influence of photoperiod

Abstract

Brown hare is a seasonal breeding mammal and under the influence of photoperiod the spermatogenesis ceases during autumn months - most markedly in September and October. Testis samples from 34 animals, sacrificed between July and December were fixed in Bouin solution, embedded in paraffin, subjected to immunohistochemistry and analysed by light microscopy. TUNEL (terminal deoxynucleotidyl transferase-mediated d'UTP nick end labeling) method was applied to detect apoptosis, anti PCNA (proliferating cell nucleolar antigen) antibodies were used to evaluate cell proliferation and antibodies against apolipoprotein D and 3beta-HSD (3beta-hidroxysteroid dehydrogenase) to evaluate the activity of the Leydig cells. Our results show that the apoptotic processes in seminiferous epithelium are obvious in August and reach peak in September, with cell death occurring during prophase of I meiotic division. In July, and from early November onwards only occasional TUNEL positive cells can be seen. The proliferation of the germ cells continues also during phase of regression (September, October and early November). Active testosterone producing Leydig cells appear to be absent in September, whereas their activity becomes obvious in the middle of November.

Proliferation and apoptosis in the seminiferous epithelium of photoinhibited Syrian hamsters (Mesocricetus auratus)1

“…Germ cell proliferation has been observed in regressed testis of animals exposed to short photoperiod, as the brown hare (Strbenc & Bavdek, 2001) and the hamster (Schlatt & Weinbauer, 1994). It has been suggested that the rate of celldivision may decrease in the testis during regression, indirectly contributing to seasonal atrophy (Young et al ., 2001).…”

Lectin Histochemistry as a Tool to Identify Apoptotic Cells in the Seminiferous Epithelium of Syrian Hamster (Mesocricetus auratus) Subjected to Short Photoperiod

“…). In these animals, there is a significant reduction in testicular volume during the non‐breeding season, accompanied by a strong increase in cell apoptosis in the seminiferous epithelium (Strbenc and Bavdek ; Young et al. ; Jenkins et al.…”

The effect of pinealectomy and leptin hormone on the proliferation and apoptosis activation in Syrian hamster testis in different photoperiods

“…Sertoli cells, spermatogonia and primary spermatocytes can be observed with the tubules. Leydig cells resemble fibroblasts (Strbenc & Bavdek, 2001). In short photoperiods (less than 12–12.5 h of light) atrophy in the testes occurs, resulting in a decrease in spermatogenesis and steroid secretion.…”

“…, 2005). It was found that, while there was an increase in apoptosis in the seminiferous tubules secondary to seasonal and photoperiodic changes, proliferation activity was retained in cells (Strbenc & Bavdek, 2001; Sato et al. , 2005).…”