Spermatogenesis in the boar.

In order to study kinetics of the spermatogenic epithelium in the adult boar, a method has been developed to prepare seminiferous tubules mounted as a whole, after which these tubules have been processed and studied as described previously only for rats, mice and hamsters. The tubules were fixed in Zenker for 24 hours and stained with periodic acid - Schiff - haematoxylin to identify the steps in spermatid development, or by Harris' hemalum to identify spermatogonia and spermatogonial divisions. Spermatid development in the boar is comparable with spermatid development in small laboratory rodents. The spermatogenic cycle was divided into 12 steps, each characterized by one step in the development of the acrosome or the shape of the nucleus of the spermatids. By studying whole mounts we could distinguish four classes of spermatogonia in the boar: undifferentiated A spermatogonia (A s, A pr, A al), differentiating A spermatogonia (A1, A2, A3, A4), intermediate and B spermatogonia. The boar demonstrates a striking similarity with small laboratory rodents.