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 PAS-Weigert-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.