Seasonal variation in the histology of the testis of the red deer, Cervus elaphus.

A histological study of the testes of stags shot in autumn (sexual season) and spring (quiescent period) indicated that the 3-fold increase in testicular size observed in the autumn was accompanied by increases in nearly all features studied (volumes of intertubular tissue, Leydig cells, blood vessels and peritubular cells; diameter and length of seminiferous tubules; the number of A1 spermatogonia and products of spermatogonial divisions, meiosis and spermiogenesis). There were, however, fewer A0 spermatogonia in the testes in autumn.