Histological and morphometric study of the epididymus of Chinchilla lanigera Grey under controlled conditions in captivity.

Chinchilla lanigera, native to the Andean Mountains of Perú, Chile, Bolivia and Argentina, is a specimen of great economic importance because of its fur. In mammals, spermatozoa originate in testes and are transported to the epididymis, where they undergo morphological and biochemical modifications known as sperm maturation, a basic step in the acquisition of their fertilizing ability. The aim of this work is the macroscopic and microscopic analysis of the epididymis of Chinchilla lanigera Grey and its sectorization based on a histomorphological study. The epididymis presents a clear segmentation into four regions: initial segment, caput, corpus and cauda. The epithelium lining the seminiferous tubules is pseudostratified, with principal cells with stereocilia and basal, clear, apical, narrow and halo cells. The histological analysis showed that principal and basal cells are the prevailing populations in all regions, also revealing narrow cells and the absence of clear cells in the initial segment. Each segment presents its different histological and morphometric characteristics, which supports the idea of the specific behaviour of each region, giving a segment-specific character to the process of sperm maturation in this species. No significant differences were found in the morphometric measurements or in the histological evaluation of the epididymis of samples collected in April and October. The fact that no differences were found between the samples collected during the two periods when the reproductive ability in nature is different suggests the importance of external factors in the control of the reproductive cycle of Chinchilla lanigera.