Inverse expression of peroxisomes and connexin-43 in the granulosa cells of the quail follicle

Studying the regulation of peroxisome (Px) expression could improve our und erstanding of human peroxisomal disorders. The granulosa of the largest pre ovulatory quail follicles proved to be a relevant model because (a) Pr expr ession changes according to the follicular maturation stage and (b) Pr expr ession varies regionally according to the distance of the granulosa relativ e to the germinal disc region containing the female gamete (oocyte). The qu estion was asked whether Pr expression is related to the extent of metaboli c cell coupling and whether zonal Pr variation is causally related to oocyt al factors. This was evaluated by the presence of catalase and Cx-43 (marke r proteins for peroxisomes and gap junctions, respectively) and by in vitro experiments with granulosa explants. The data obtained show that the expre ssion of Cx-43 and Pr is inversely correlated both temporally and spatially . Uncoupling of gap junctions results in an upregulation of alpha-catalase immunofluorescence. This is in agreement with reports that gap junctions ar e often negatively affected by Pr proliferators. The zonal gradient in Pr e xpression appears to be imposed by the oocyte, as is the case for steroidog enesis and proliferative capacity in the granulosa epithelium.