TRANSFORMING GROWTH-FACTOR-ALPHA GENE-EXPRESSION AND PEPTIDE LOCALIZATION IN PORCINE OVARIAN FOLLICLES

The present study was undertaken to determine transforming growth fact or alpha (TGF alpha) gene expression in various components of medium-s ized porcine ovarian follicles by reverse transcription-polymerase cha in reaction, and to localize the peptide during folliculogenesis by im munocytochemistry. A strong signal for TGF alpha transcript was detect ed in cumulus and granulosa cells, whereas the signal in theca cells w as very weak but detectable, No TGF alpha mRNA was detected in the ooc yte. Immunolocalization studies revealed intense TGF alpha staining in cumulus and granulosa cells of all stages of follicular development. TGF alpha immunostaining was also observed in the oocytes of primordia l and primary follicles, In antral follicles, immunostaining was obser ved only in cumulus and mural granulosa cells, whereas theca cells and oocytes exhibited very little or no detectable staining, TGF alpha im munostaining was absent in follicles undergoing atresia. No TGF alpha immunostaining was observed when the antibody was omitted from the pro cedure, and the staining was substantially reduced when the primary an tibody was preabsorbed with the same mass of TGF alpha peptide, sugges ting the specificity of the staining procedure. These results suggest a local follicular production of TGF alpha in the porcine ovary and th us a role for TGF alpha of follicular origin in the regulation of foll icular development in an autocrine/paracrine fashion.