Type VI collagen expression during growth of human ovarian follicles

Abstract

Objective: To identify type VI collagen expression in human ovarian follicles during follicular growth. Design: In vitro experiment. Setting: Department of Obstetrics and Gynecology, Wakayama Medical College, Japan. Patient(s): Regularly cycling women who underwent adnexectomy. Intervention(s): Immunohistochemistry and in situ hybridization for human type VI collagen. Main Outcome Measure(s): Expression of type VI collagen. Result(s): Expression of type VI collagen was observed in the theca cell layers during folliculogenesis, whereas no expression of type VI collagen was observed in the granulosa cell layers at the mRNA and protein levels. As the follicles grew, immunostaining for type VI collagen became intense in the theca cell layers, especially the theca externa. In preovulatory follicles, however, weak, fragmented, or discontinuous immunostaining of the theca cell layers was observed. This fragmented or discontinuous immunostaining was evident predominantly in the apical area of preovulatory follicles rather than in the basal area. Conclusion(s): Type VI collagen is present in the theca cell layers of follicles during folliculogenesis and plays an important role in interactions between the theca cells and extracellular matrix. These interactions may lead to changes in the shape, proliferation, migration, or differentiation of follicular cells during follicular development, maturation, and ovulation.