Partial synchronization of spermatogenesis in the immature Djungarian hamster, but not in the immature Wistar rat.

The frequencies of the cellular associations of the seminiferous epithelium were determined at various ages after birth in immature Djungarian hamsters and Wistar rats. The frequencies of the cellular associations present in immature animals were then compared with the frequencies of the corresponding pooled stages in adult animals. At 15 days of age, the cellular associations present in Djungarian hamsters could be divided into four groups based on the presence of A3, intermediate (In), or B (B1 and B2) spermatogonia, or preleptotene-leptotene-zygotene spermatocytes. Compared with adult animals, the group containing spermatocytes was found to be enriched by 52%, while the frequency of the B spermatogonia was reduced by 55%. At 22 days of age, the cellular associations of spermatogenesis were classified into five groups: pachytene spermatocytes associated with A3 spermatogonia. In spermatogonia, B spermatogonia, or preleptotene-leptotene-zygotene spermatocytes, or the meiotic divisions. The stages containing preleptotene-leptotene-zygotene spermatocytes and those containing A3 spermatogonia were enriched by 35% and 59% compared with adult values, respectively. The meiotic divisions were enriched by 21%, but this increase was not significant. The frequency of the B spermatogonia was reduced by 62%. In addition, the synchronization factor, calculated with the computer program SYNTEST, was increased to 1.48 +/- 0.05 (mean +/- SEM) and 1.38 +/- 0.03 at 15 and 22 days of age, respectively, and was significantly higher (P < 0.001 at both ages) than the adult value of 1.08 +/- 0.02. However, after 22 days of age the synchronization factor did not differ from that in adult animals.(ABSTRACT TRUNCATED AT 250 WORDS)