A Monoclonal Antibody to a Mammary Cell Line Recognizes Two Distinct Subtypes of Ovarian Granulosa Cells*

Abstract

When screening supernatant fluids from hybridoma clones, Dulbecco and co-workers found that a mouse monoclonal antibody generated against a mammary tumor cell line showed rather striking high binding to rat oocytes and granulosa cells. In this study we have specifically investigated the reactivity of the monoclonal antibody (designated anti-OA-1) with granulosa cells during the differentiation process. This was accomplished using the two-step indirect immunocytochemical technique. When a primordial follicle is recruited to initiate growth, intense immunoreactivity appears in the surface membrane of the granulosa cells. As a follicle proceeds through the preantral stages, the plasma membrane of the granulosa cells is strongly positive for anti-OA-1 reactivity, and the granulosa appear as a homogeneous population. However, once Graafian follicle development is initiated, a major shift in anti-OA-1 immunoreactivity occurs among the granulosa cells. As the antrum expands, 75% of the granulosa in the mural region (those nearest the basal lamina) elongate and become negative for anti-OA-1. This is in contrast to the periantral and cumulus granulosa, which remain rounded and show strong anti-OA-1 reactivity up to the preovulatory stage. The disappearance of anti-OA-1 reactivity in the subpopulation of mural cells is specifically initiated by FSH and occurs very rapidly after a 12-h lag phase. After the loss of anti-OA-1 reactivity, the elongated mural granulosa cells express their terminal differentiated state by acquiring LH/hCG receptor, 3 beta-hydroxysteroid dehydrogenase activity and cytoplasmic lipid inclusions. By contrast, the periantral and cumulus granulosa, which remain positive for anti-OA-1, do not express these differentiated functions; however, they do differentiate ultrastructurally, indicating that they respond to the FSH signal. These results strongly suggest that a monoclonal antibody recognizes a major surface differentiation antigen in the granulosa cell. This antigen is under hormonal control and is inversely linked to expression of the terminal differentiation program in the granulosa cells. We anticipate that the monoclonal antibody will be a valuable probe to aide in the analysis of structure/function relationships in subpopulations of granulosa cells.

Follicular growth and regression during the 8 days after hypophysectomy in sheep

“…This heterogeneity in the fate of the follicles after withdrawal of gonadotrophin support has also been described for barbiturate-blocked rats (Braw & Tsafriri, 1980), since ovulatory efficiency in response to hCG decreased from 88 to 70, 52 and 31% after 1, 2, 3 and 4 days of blockade. This might be linked to the between-follicle balance in the different subtypes of granulosa cells (Erickson et al, 1985;Kasson et al, 1985).…”

The transient disappearance of cytokeratin in human fetal and adult ovaries

“…The density of the endocrine receptors and the intensity of steroidogenesis are higher in the outer layer, whereas the proliferative activity is higher in the inner oocyteassociated layer (Erickson et al 1985;Amsterdam et al 1989;Vanderhyden and Macdonald 1998). Only cumulus cells expand by "mucification".…”

Granulosa Cells Express Integrin α6: Possible Involvement of Integrin α6 in Folliculogenesis

“…By analyzing these antigens, numerous new regulatory mechanisms of differentiation have been revealed. In the field of ovarian research, Alila and Hansel [1] [2,3] reported two mAbs (OA-1 and OA-2) raised against a rat mammary tumor cell line. Although their expression was not specific to granulosa cells in the ovary, the antigen expression profiles on gran ulosa cells were related to the differentiation state, sug gesting the usefulness of mAbs to analyze ovarian follicu lar differentiation.…”