Localization of an activin/activin receptor system in the porcine ovary

Abstract

The aim of this study was to locate a possible activin/activin receptor system within porcine ovaries containing functional corpora lutea. In situ hybridization was used to assess the gene expression of beta(A)- and beta(B)-activin subunits, and immunohistochemical studies were done to detect activin-A protein and activin receptor type II. mRNA expression of the beta(A)- and beta(B)-activin subunits was found in the granulosa from the unilaminar follicle stage onward, in the developing thecal layer of multilaminar and small antral follicles, in the theca interna of mid-sized antral follicles, in corpora lutea, and in the ovarian surface epithelium. Immunoreactive activin A protein could be detected at the same ovarian sites, but in thecal tissue of small antral follicles only. This protein was also demonstrated at the peripheral zone of oocytes from multilaminar and antral follicles. A positive immunoreaction for activin receptor was found in granulosa cells from multilaminar and older follicles and in oocytes from the earliest stages of follicular development onward. In late multilaminar follicles and in antral follicles, the oolemma was stained. Except for small antral follicles, a positive activin receptor immunoreaction was absent in the follicular theca. Activin receptor immunoreaction was furthermore present in corpora lutea and in the ovarian surface epithelium. It is concluded that, within porcine ovaries containing functional corpora lutea, an activin/activin receptor system is present in all intact follicles, the corpora lutea and the surface epithelium. Within follicles, granulosa and theca cells are the main sites of activin synthesis, while oocytes and granulosa cells are the main activin binding sites.

Molecular characterization of Activin Receptor Type IIA and its expression during gonadal maturation and growth stages in rohu carp

“…This is the first study in rohu showing ActRIIA gene expression during different reproductive stages. The results of high levels of expression in gonad tissue during the pre-spawning stage are indicative of the significant role of ActRIIA in stimulating oocyte maturation and spermatogenesis which is consistent with the reports of previous studies in zebrafish and other vertebrate species (Wu et al, 2000;Van den Hurk and Van de Pavert, 2001;Pangas et al, 2002;Silva et al, 2004). Activin receptors act in both autocrine and paracrine fashion through pituitary-activin signaling process.…”

Intraovarian Activins Are Required for Female Fertility

“…Whereas no definitive data exist for activin in luteolysis, a number of studies suggest that activin plays an active role in regression of CLs. First, activin receptors localize to CLs in many species (61)(62)(63). And second, the activin antagonist follistatin is highly expressed in newly formed rodent CLs but undetectable during luteolysis (64), resulting in a permissive environment for activin signaling.…”

Activin B is produced early in antral follicular development and suppresses thecal androgen production

“…1990). Activin βA and βB subunit mRNA was detected in GCs and TCs from small porcine antral follicles (van den Hurk & Van de Pavert 2001). In sheep ovaries, no inhibin α had previously been detected in TCs but was detected in GCs of some healthy antral follicles at all stages of the estrous cycle (Tisdall et al .…”

“…Activin has been localized to oocytes and GCs in rodents, pigs, and cows (Hulshof et al . 1997, van den Hurk & Van de Pavert 2001, Zhao et al . 2001) and in human GCs and TCs (Roberts et al .…”