SEMINIFEROUS TUBULES WALL CONTRACTION WITH ENDOTHELIN-1

LOSINNO A.D; SORRIVAS V; LÓPEZ L.A; MORALES A

Mendoza

Congreso; XXXI Reunión Anual Sociedad de Biología de Cuyo; 2013

Sociedad de Biología de Cuyo

Peritubular myoid (PM) cells form a monolayer which surrounds the seminiferous tubules (ST) in rodents. These cells are in turn covered by a monolayer of endothelial cells (EC) from lymphatic vessels. Both monolayers constitute the ST wall, joined by spaces with collagen fibers. PM are smooth muscle cells, with α-actin filaments arranged in two independent layers. PM cells contract with endothelin-1(ET1), a peptide synthetized by Sertoli cells. The aim of this work is to describe morphological changes of the ST wall during contraction, adding information from light, confocal, and electron microscopes (transmission and scanning SEM). To study PM cells surface by SEM, a previous digestion of the EC monolayer was needed. ET1 makes PM cells contract, folding their nuclei, changing their shape to a more rounded one, and reducing their area. Also, PM cytoskeleton changes: the two independent layers of α actin appeared denser, and the outer longitudinal layer tends to make ribbons that cover the nuclei. This correlates with the images of PM cells surface obtained by SEM when the EC monolayer has been digested. In contracted ST, big foldings appear in parallel to ST axis, in contrast with relaxed ST, where PM are polygonal flat cells with smooth surface. As a consequence of PM cell contraction, EC show numerous protrusions towards the interstitium, basement membranes get waved and the collagen fibers, that anchor PM cells with endothelium and epithelium, change their orientation.