The contractibility of peritubular myoid cell changes along the seminiferous tubule.

LOSINNO A.D., MORALES A., BERTOLDI M.V., AMAYA M.C, COSTANTINO V.V. AND L.A. LÓPEZ

San Luis

Congreso; 47 th Annual Meeting Argentine Society for Biochemistry and Molecular Biology; 2011

Sociedad Argentina de Investigaciones Bioquímicas

The myoid cells (MC) have contractile activity and express typical proteins of smooth muscle cells such as α-actin and miosin II. Along the seminiferous tubules (ST), the germinal epithelium presents specific cell asotiations called stages (numbered from I to XIV in rat). In a previous work, we observed that MC contain an external layer actin filaments bundles (AF) distributed homogeneously in the cytoplasm in cells of the ST segments with VII-VIII stages, but only along of nuclear zone in cells of the ST segments with II-III and IX-X stages. We asked wether the MC cells have specific contraction features in each ST segment. We analyzed the morphology of the MC in each ST segment and the changes produced by the contraction. ST from adult rats were incubated with 0 and 50 nM endothelin-1 (ET-1) and fixed. The segments corresponding to II-III, VII-VIII and IX-X stages (segments A, B and C respectively) were isolated by transillumination, incubated with alfa-actin-FITC and observed by confocal microscopy. The area of MC was of 2068.58±63.24, 1892.52±64.40, 1770.95±62.39 µm2 (X±SEM).in the segments A, B and C respectively. By the contraction with ET-1 the MC area was reduced 36.5±2.3, 20.4±1.6 and 37.9±5.1% respectively. These results indicate that the contractibility of MC changes along the ST and probably is related to the distribution in the cytoplasm of the external layer of AF.