Expression of connexin 43 mRNA and protein in developing follicles of prepubertal porcine ovaries

A major form of cell-cell communication is mediated by gap junctions, aggre gations of intercellular channels composed of connexins (Cxs), which are re sponsible for exchange of low molecular weight ( < 1200 Da) cytosolic mater ials. These channels are a growing family of related proteins. This study w as designed to determine the ontogeny of connexin 43 (Cx43) during early st ages of follicular development in prepubertal porcine ovaries. A partial-le ngth (412 base) cDNA clone was obtained from mature porcine ovaries and det ermined to have 98% identity with published porcine Cx43. Northern blot ana lysis demonstrated a 4.3-kb mRNA in total RNA isolated from prepubertal and adult porcine ovaries. In-situ hybridization revealed that Cx43 mRNA was d etectable in granulosa cells of primary follicles but undetectable in dorma nt primordial follicles. The intensity of the signal increased with follicu lar growth and was greatest in the large antral follicles. Immunohistochemi cal evaluation indicated that Cx43 protein expression correlated with the p resence of Cx43 mRNA. These results indicate that substantial amounts of Cx 43 are first expressed in granulosa cells following activation of follicula r development and that this expression increases throughout follicular grow th and maturation. These findings suggest an association between the enhanc ement of intercellular gap-junctional communication and onset of follicular growth. (C) 2001 Elsevier Science Inc. All rights reserved.