New insights into epididymal function in relation to sperm maturation

Abstract

Testicular spermatozoa acquire fertility only after 1 or 2 weeks of transit through the epididymis. At the end of this several meters long epididymal tubule, the male gamete is able to move, capacitate, migrate through the female tract, bind to the egg membrane and fuse to the oocyte to result in a viable embryo. All these sperm properties are acquired after sequential modifications occurring either at the level of the spermatozoon or in the epididymal surroundings. Over the last few decades, significant increases in the understanding of the composition of the male gamete and its surroundings have resulted from the use of new techniques such as genome sequencing, proteomics combined with high-sensitivity mass spectrometry, and gene-knockout approaches. This review reports and discusses the most relevant new results obtained in different species regarding the various cellular processes occurring at the sperm level, in particular, those related to the development of motility and egg binding during epididymal transit.

Adolescence and the next generation

“…Sperm maturation takes between 70 and 100 days in humans, predominantly in the seminiferous tubules that are in constant contact with supporting Sertoli cells. This is followed by a 1-2 week transitional period in the epididymis, during which time proteins and a small amount of RNA are selectively shuttled into the developing sperm 51,52 . The paternal preconception environment modulates the RNA content of the developing sperm, with possible effects on post-fertilization development and offspring phenotypes 53 .…”

Interpreting histopathology in the epididymis

“…This, together with their acquisition of clusterin in the caput sperm, appears to facilitate subsequent migration of the cytoplasmic droplet and increased capacity for motility as sperm transit the epididymal duct. 7 The epididymis is highly androgen-dependent with androgen supplied by the testicular fluid entering the duct as well as via the vasculature in the interstitium of the duct. Testosterone (T) and dihydrotestosterone (DHT) are involved in both the maturation and transit of sperm through the duct.…”

Comparative proteomic analysis of heat stress proteins associated with rat sperm maturation

“…Heat stress may have a negative effect on male fertility through oxidant damage by producing ROS and further changing the intracellular signal transduction (15). This effect may induce germ cell loss and poor semen quality, however, its effect on sperm maturation, particularly on the sperm maturation milieu, is not clear (16,17). In the present study, a short-term heat stress was performed on rats by exposure to high environmental temperature (42˚C) for 1 h, followed by identification of altered key sperm milieu proteins by comparing a proteomic analysis of caput epididymal fluids.…”