The high frequency of apoptosis during the immature spermatogenic stages VII and VIII was associated with midpachytene spermatocytes. In connection with these two stages, the frequency of apoptosis at 18 and 26 days of age was the same, whereas the total number of pachytene spermatocytes increased with increasing age, suggesting that cell density is not involved in regulating programmed cell death in this case. This pattern of elevated apoptosis in pachytene spermatocytes only during stages VII-VIII is identical to that observed after hypophysectomy. In the latter case, lack of stimulation of Leydig cells by luteinizing hormone leads to a decrease in testosterone production, which in turn causes increased apoptosis in pachytene spermatocytes and spermatids at stage VII. dexone tablets
In the present study, the absence of haploid step 7-8 and elongated step 19 spermatids were the major features that distinguished spermatogenic stages VII and VIII in immature testis from the corresponding mature stages. In connection with pubertal spermatogenesis in the golden hamster, cessation of early spermatogenic apoptosis is known to coincide with the initiation of spermatid elongation. During stages VII-VIII in the mouse, round spermatids secrete the paracrine factors Bmp8a and Bmp8b, which promote the survival of spermatocytes. Accordingly, enhanced spermatocyte apoptosis is observed in mice in which the genes encoding these factors are defective. Thus, in the immature testis, an absence of survival signals from round spermatids may contribute to the high frequency of apoptosis in spermatocytes.