Lipid droplets in fractions enriched in spermatocytes, spermatids and residual bodies

ORESTI, G. M.; REYES, J. G.; AVELDAÑO, M. I.

Mar del Plata

Congreso; XLIII Reunión Nacional de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB); 2007

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

LIPID DROPLETS IN FRACTIONS ENRICHED IN SPERMATOCYTES, SPERMATIDS AND RESIDUAL BODIES   Oresti GM1, Reyes JG2 and Aveldaño MI1 1INIBIBB, CONICET-UNS, 8000 Bahía Blanca, Argentina 2INST. de QCA., PUCV, Chile. In seminiferous tubules, Sertoli cells play a chief role in providing structural and functional support to the spermatogenesis. Those germ cells that cannot be supported are led into apoptosis and rapidly eliminated by phagocytosis. At their luminal pole, Sertoli cells are also involved in supporting spermiation: as spermatids are released from the seminiferous epithelium, residual bodies are rapidly engulfed and degraded in Sertoli cells. In this work we isolated cell fractions enriched in pachytene spermatocytes, spermatids, and residual bodies to study their lipids and fatty acids. None of the germ cell fractions contained cholesterol esters, confirming that within seminiferous tubules these lipids are exclusive of Sertoli cell droplets. Glycerophospholipids rich in 22:5n-6 and sphingomyelin with 28:4n-6 and 32:5n-6 were more abundant in spermatocytes and especially in spermatids than in residual bodies. In contrast, the latter contained the highest proportion of 22:5-rich triglycerides of the three fractions. When Nile Red was used as a marker of oil droplets, spermatocytes and spermatids stained faintly and residual bodies fluoresced strongly and punctuated, indicating that 22:5-rich triglycerides were the main components of lipid droplets located within these bodies. In vivo, recycling of the lipid constituents including 22:5 may be one of the duties of Sertoli cells.