Chapter 22 - The Epididymis
B Robaire, BT Hinton, MC Orgebin-Crist
Publisher Summary
This chapter focuses on the embryonic origins of the different regions of the epididymis. It appears that the efferent ducts are derived from the mesonephric tubules, whereas the caput epididymidis to the vas deferens regions are derived from the mesonephric duct. The cells of the initial segment are quite distinct from either the efferent ducts or the distal epididymal regions, but function similarly to the efferent ducts in that they are actively involved in water reabsorption. By birth, the epididymis has undergone considerable coiling in the proximal regions (initial segment to corpus) and the cauda has yet to complete coiling. In the next 1 to 2 days, individual septa are seen delineating the tubule into segments. The mechanisms that regulate the growth and differentiation of the epididymal duct are unknown, although it is clear that the expression of many epididymal genes is developmentally regulated. Certainly, luminal and circulating androgens play a critical role, but luminal fluid factors other than androgens also may be important.