The effects on the proximal caput epididymidis of efferent ductule ligation were studied. After 6 h there was a slight increase in autophagocytosis in the initial segment proper (1A). After 12 h this segment showed cell death and cytoplasmic regression and after 24 h large amounts of necrotic cells and focal degeneration in the epithelium, and desquamated cells and débris in the lumen. After 48 h the epithelium was lower, but degeneration less obvious. Segments 1B, 1C and 2 showed marked cell death and cytoplasmic degeneration. This was more evident after 3 days, especially in 1B. After 5 and 7 days some degeneration was still seen, but essentially regional differences had disappeared, leaving a lower, inactive epithelium throughout. Except for an increase in glycogen granules in segment 1C after 48 h, marked focal degeneration always appeared before general cytoplasmic alterations. Sham operation produced no changes. The regression might be caused by the cut supply of androgen binding protein or a growth factor in rete testis fluid.

Summary. Volume

The volume of the blue fox testis showed 5-fold changes during the year, associated with considerable changes in cellular composition. The seminiferous epithelium was maximally regressed in August, when 94% of tubules contained only spermatogonia. By late October, approximately 6 months before the mating season, 40% of tubules contained primary spermatocytes. From the middle of January until the end of April all tubules contained spermatids or more advanced haploid cells. Tubular diameter increased by 73% during testicular re-development, and epithelial height increased 3-fold. Regression to the basal state occurred during May to July. The volume densities of the seminiferous epithelium and of interstitial tissue remained approximately constant throughout the year. Soluble Mn2+-dependent adenylate cyclase activity showed seasonal variations that paralleled those of the haploid germ cell population and testicular volume, whereas somatic cell adenylate cyclase activity was relatively constant.