DEVELOPMENTAL-CHANGES IN THE EXPRESSION OF THE GROWTH-HORMONE RECEPTOR MESSENGER-RIBONUCLEIC-ACID AND PROTEIN IN THE BOVINE OVARY

By reverse transcription-polymerase chain reaction, the transcript of the growth hormone receptor (GHR) was demonstrated in oocytes, follicu lar cells, and corpus luteum of the bovine ovary. Immunoblotting using the monoclonal antibody mAb 263 resulted in a distinct protein band a t 120 kDa, confirming that translation of the mRNA takes place in the same cells. Nonradioactive in situ hybridization revealed that distrib ution of the mRNA encoding GHR was correlated with the developmental s tage of the follicle. Whereas in primordial and primary follicles the oocyte showed distinct amounts of the transcript encoding GHR, in tert iary follicles the mRNA was predominantly localized in the cells of th e cumulus oophorus. GHR mRNA was also expressed in the large granulosa lutein cells, in the germinal epithelium, and in the endothelial cell s of ovarian vessels. Colocalization of the GHR protein showed a distr ibution pattern identical to that of the mRNA. In carves, oocyte and f ollicle cells changed GHR expression in the same way as in the adult o vary. During embryonic development of the ovary, distinct amounts of t he mRNA encoding GHR were found in primordial follicles shortly before birth. Our results imply that the GHR is involved in ovarian ontogene sis, especially in early folliculogenesis.