Immunocytochemical localization of follicle regulatory‐protein (FRP) in testis

Abstract

Follicle regulatory protein (FRP) can exert paracrine control over follicular development. It is synthesized by the granulosa cells of the developing follicles and was localized in the cytoplasm of the mural cells by immunocytochemistry. When administered to male dogs and rats, FRP causes impairment of spermatogenesis. In the intact male rat, it has been postulated that FRP manifests its effects at a stage prior to the conversion of testosterone to dihydrotestosterone. Sertoli cells of the seminiferous tubules are implicated in testosterone metabolism. Furthermore, Sertoli cells in male gonads are regarded as the counterpart of granulosa cells in ovaries. The exact source of FRP in the male is not known. Therefore, it was of interest to study the localization of FRP in the male gonads. Testicular sections of the pig, dog, cat, rat, mouse, monkey, and man were immunocytochemically stained with monoclonal antibody to porcine FRP of ovarian origin. Sections of pig ovaries were used as controls throughout the study. Specificity of immunocytochemical localization was established by preabsorption. FRP antibody predominantly localized to the interstitial compartment of the pig testis. In the seminiferous tubules, FRP localization was limited to basal spermatogonia and Sertoli cells of tubules at few specific stages of spermatogenesis. The study also showed that the monoclonal antibody against porcine FRP is species-specific. Antibody binding was found only in pig testis, whereas tissues from the cat, dog, mouse, rat, monkey, and man did not display any immunocytochemical reaction.(ABSTRACT TRUNCATED AT 250 WORDS)

Purification of Follicular Regulatory Protein: Possible Plasminogen Identity

“…FRP is believed to (a) inhibit microsomal aromatase activity and microsomal 3B-hydroxysteroid dehydrogenase activity in vitro (12)(13), (b) inhibit thecal aromatase activity from large and medium-sized follicles of pigs (16,17), (c) alter the production and secretion of progesterone from granulosa cells in vitro (14 -15), (d) inhibit the increase in ovarian weight and serum estradiol levels in hypopophsectomized, immature, diethylstilbestrol-treated female rats (2), (e) inhibit granulosa cell and placental microsomal aromatase activity (3-7), (f) delay follicular maturation in spontaneously cycling monkeys (8), (g) inhibit FSH induction of LH/hCG receptors in porcine granulosa cells (9), (h) associate with perifollicular neovascularization during folliculogenesis (10,11), (i) inhibit spermatogonial transformation from type A into type B in vivo (18), (j) disrupt seminiferous epithelial function and reduce sperm production after injection of FRP into rats (19 -21), (k) alter follicular steroid secretion and thecal morphology (24), (l) fluctuate during the menstrual cycle (25,26), (m) increase in persons with reproductive disorders (23), and finally, using the monoclonal antibody 1A8D5, FRP was suggested as a novel marker for granulosa cell cancer patients (27) and inhibit ovarian cancer cell proliferation (22). In addition monoclonal antibody 1A8D5 was also used to localize FRP in the granulosa cells of porcine follicles (28,29) and testes (30). We now report the isolation of an antigen recog-nized by monoclonal antibody 1A8D5 that appears to be a plasminogen protein.…”