Testicular histology of cryptorchid black-tailed deer (Odocoileus hemionus sitkensis) of Kodiak island, Alaska

摘要

Histological structure of intraabdominally located testes and epididymis of cryptorchid black-tailed deer (Odocoileus hemionus sitkensis) of Kodiak island, Alaska was compared with the gonads of intact deer sampled in the same region. The deer were harvested during the rut and their age, antler and gonadal status were recorded. The seminiferous tubules of cryptorchid bucks were malformed, lined only with Sertoli cells and were devoid of any spermatogenetic activity. A great number of blood vessels including arteries were detected within the remnants of tubules. In addition, inclusions comprised of concentric lamellae, containing most probably calcium salts, were observed in the lumen of degenerated tubules. Conversely, we encountered large areas of cells resembling Leydig cells, exhibiting an abundant cytoplasm. The production of testosterone in these cells would explain why an almost normal antler shape and a quasi-normal antler cycle were often observed in many bilateral cryptorchids. Epididymides accompanying the ectopic testes were devoid of any spermatozoa but otherwise were of almost normal size; only in the bilateral cryptorchid the epithelium was partly malformed. It was concluded, that hypoplastic or cryptorchid testes cause male infertility but the production of testosterone in the less affected Leydig cells is sufficient to initiate and control the antler cycle.