A study of germ cell morphology and duration of spermatogenic cycle in the baboon,Papio anubis

Biopsy and orchiectomy specimens were collected from two adult baboons (Papio anubis) at different intervals after intratesticular injection of H³-thymidine. Zenker-formol or Bouin's fixed materials were stained with PASWeigert-Hematoxylin and radioautographed using the H.S.R. (Harleco Synthetic Resin) coating technique. Morphological features of most germ cells appeared similar to those of other monkeys, except that the spermatids in steps 9 to 11 showed a spike-like projection of the acrosome. Also, the type A spermatogonia showed some resemblance to the human type A spermatogonia. The cell associations consisted of 12 stages and a large number of tubular cross sections showed the presence of two or more stages. In Papio anubis, the zygotene spermatocytes are formed in stage VIII, and spermatozoa are released during stages V and VI. H³-thymidine labeling of germ cells indicated that one cycle of spermatogenesis in this species takes approximately 11 days, and complete spermatogenesis occupies 3.8 cycles, or approximately 42 days. The presence of labeled B type spermatogonia 35 days after H³-thymidine injection indicated the existence of some stem cells. The presence of some labeled Ad spermatogonia in these specimens could not be explained. The data indicated that spermatogenesis in this monkey is somewhat different from that in other monkey species described.