Regulation of apoptotic cell death in the rat epididymis.

The rat epididymis decreases markedly in weight after orchidectomy. In these studies, we demonstrate that a time-dependent wave of apoptotic cell death occurs in some principal cells after orchidectomy. This wave moves coincidentally with the luminal content of the epididymis. Androgen treatment at the time of orchidectomy can prevent apoptotic death in all regions of the epididymis except the initial segment (Robaire and Hermo, 1988, similar to zone 1a defined by Reid and Cleland, 1957). After unilateral efferent duct ligation, apoptotic cell death in the initial segment of the epididymis is similar to that seen after orchidectomy, reduced in the caput (zones 1b,c, 2 and 3 as defined by Reid and Cleland, 1957) and absent from the corpus (defined as zones 4, by Reid and Cleland, 1957) and cauda epididymidis (defined as zones 5 and 6 by Reid and Cleland, 1957). Together, these results indicate that principal cells differ in their responses to androgens and other testicular factors both in any given cross-section and with respect to their position along the epididymis.