Duration of spermatogenesis and relative frequency of each stage in the seminiferous epithelial cycle of the chimpanzee

To determine the duration of 1 spermatogenic cycle, a single pulse of tritiated thymidine was infused into a branch of the spermatic artery in each of 3 chimpanzees (Pan troglodytes). Samples were recovered surgically prior to infusion, at 1 h, and at 3, 8, 14, 16, 17, 28, 30, 33, 40, 44, and 48 days postinfusion. Tissues were fixed in Bouin's solution, dehydrated, paraffin-embedded, sectioned at 5 micrometers, and stained. Pre-infusion samples were used in morphometric studies to estimate the percentage frequency of area occupied by each of the 6 cellular associations (stages I-VI) characteristic of chimpanzee spermatogenesis, and thus, to estimate the days duration of each stage. To estimate the duration of 1 spermatogenic cycle, pre- and post-infusion, tissue sections were coated with undiluted Kodak NTB2 liquid autoradiographic emulsion and incubated at 4 +/- 1 degree C. At optimum exposure times, slides were processed with Kodak D-19 and Fixer; light microscopic analyses were conducted to determine the most mature labeled cell in stage III for each of the sample times. The duration of the 6 stages (I-VI) are 4.2, 2.0, 4.3, 1.5, 1.3 and 0.6 days, respectively, and the duration of 1 spermatogenic cycle is approximately 14 days. Thus, the duration of spermatogenesis from the Ap spermatogonium to mature Sd2 spermatid is approximately 62.5 +/- 1.5 days or 4.46 spermatogenic cycles.