The transient disappearance of cytokeratin in human fetal and adult ovaries

Abstract

Cells from the inner and outer granulosa cell layers of the ovarian follicles differ in function, probably because of their different origins from the surface epithelium and from the rete. This suggestion has not so far been thoroughly investigated in the human ovary. We examined fetal ovaries from the early, middle and late gestational periods, ovaries from fertile women, and preovulatory follicular cells obtained from patients under in vitro fertilization therapy (IVF). Indirect immunohistology and immunocytology were used to detect the presence of cytokeratin (CK)-positive epithelial cells. In fetal ovaries from the early gestational period, prominent rete tubules (sometimes with oocytes) appeared to be fused with the sex cords and primordial follicles. Both showed CK-positively, detected with the pan-CK antibody Lu-5. Cytokeratin 19 was clearly expressed in the fusion area. In the fetal and adult ovaries, CK-positive follicular or granulosa cells were noted in the primordial and primary follicles as well as the preovulatory follicles. Cytokeratin was not detected in the granulosa cells of growing follicles, CK-positive and -negative luteal cells were identified in the developing corpus luteum. We conclude for the human ovary: (1) the heterogeneous morphology of granulosa cells may be explained by their twofold origin from the surface epithelium and the rete, (2) the rete tubules appear to be involved in folliculogenesis, (3) the transient absence of CK expression in growing follicles compared to resting and mature follicles or to the developing corpus luteum indicates a particular role of CK-positive cells at the periovulatory period.

Immunohistochemical Characterization of Normal Ovary and Common Epithelial Ovarian Neoplasm with a Monoclonal Antibody to Cytokeratin and Vimentin

“…In normal ovaries, surface epithelial cells are strongly immunostained for CK AE1/AE3 and faintly expressed vimentin. The expression of CK and vimentin in ovarian surface epithelium was not surprising depending on its embryonic origin from the coelomic epithelium, which demonstrates similar expression (6). Granulosa cells of ovarian follicles showed the presence of both CK AE1/AE3 and vimentin in all stages of development, with some deviations, depending on the developmental stage.…”

Five different phenotypes of endothelial cell cultures from the bovine corpus luteum: Present outcome and role of potential dendritic cells in luteolysis

“…The CL of pregnancy lacks any steroidogenic CK + cells. In analogy to the transient disappearance of CK expression in granulosa cells of growing follicles (Löffler et al, 2000), the same possibility is theoretically given for the CL system and would compare with the spontaneous loss of CK 8 gene expression in transformed cells (Knapp and Franke, 1989). Switching off one of the CK genes leads to the disappearance of CK filaments and to CK filament- as shown for the fetal ovary (Löffler et al, 2000).…”

“…On the contrary, the study of CK + follicle cells is widely neglected. In the fetal period, CK + follicle cells of primordial follicles arise from the medullar part of the sex cords of bovine and human ovaries (Löffler et al, 2000).…”

“…In analogy to the transient disappearance of CK expression in granulosa cells of growing follicles (Löffler et al, 2000), the same possibility is theoretically given for the CL system and would compare with the spontaneous loss of CK 8 gene expression in transformed cells (Knapp and Franke, 1989). Switching off one of the CK genes leads to the disappearance of CK filaments and to CK filament- as shown for the fetal ovary (Löffler et al, 2000). The aorta-gonado-mesonephric region Page 11 of 26 A c c e p t e d M a n u s c r i p t 11 is coined by the passage of primordial germ cells immigrating from the dorsal yolk sac through the dorsal mesogastrium into the genital ridge around week 6 in the human embryo (Sadler, 2000).…”

Ovarian Follicular Atresia

“…The intermediate filaments, including vimentin, the cytokeratins, and desmin, are thought to influence cell mitosis, follicular atresia, and de-differentiation of cells of the follicle (van den Hurk et al, 1995;Khan-Dawood et al, 1996;Loffler et al, 2000). These so-called "stress filaments" also participate in the maintenance of cell contact between the oocyte and cumulus cells, orchestrate distribution of organelles throughout the cytoplasm of the oocyte, and possibly control resumption of its meiotic division (Gall et al, 1992), in part by influencing cumulus expansion (Šutovský et al, 1995).…”