Quantitative Evaluation of the Cell Cycle-Related Retinoblastoma Protein and Localization of Thy-1 Differentiation Protein and Macrophages during Follicular Development and Atresia, and in Human Corpora Lutea1

Abstract

Ovarian follicular development is dependent on growth and differentiation of the oocyte, as well as the granulosa and theca cell layers. The majority of primary follicles in the adult human ovary are not growing, and most antral follicles undergo atresia. The mechanisms regulating follicular growth and differentiation are poorly understood. Expression of key regulatory proteins in cells of certain follicles may be involved. We have studied the distribution of retinoblastoma protein (pRb), a key cell cycle regulator, in human follicles and CL by quantitative immunohistochemistry. Recent studies suggest that high nuclear concentrations of pRb are associated with the arrest of cell proliferation and the beginning of differentiation; during advanced differentiation of cells pRb is markedly depleted or absent. We also studied follicular distribution of Thy-1 differentiation protein, a morpho-regulatory molecule associated with cell differentiation, and the presence of macrophages. Macrophages have been shown to stimulate steroidogenesis in granulosa cells in vitro, and they are required for release of Thy-1 differentiation protein from vascular pericytes among granulosa cells in vivo. Our results indicate that oocytes in resting follicles exhibit pRb in the nucleoli. During initiation of follicular growth, the pRb expression first extends over the oocyte nuclei and then diminishes from both nuclei and nucleoli in preantral follicles. When the oocytes reach maximum size in small antral follicles, the pRb expression is reestablished in oocyte nucleoli. In differentiating granulosa and theca cell layers of preantral and small antral follicles, pRb expression is high, but it is low in growing large antral follicles. During CL development and regression, pRb expression in the nuclei of granulosa lutein cells first increases and then decreases. Follicular development is accompanied by the presence of Thy-1 differentiation protein and macrophages under the follicular basement membrane. In growing large antral follicles, during the mid-follicular phase, larger macrophages exhibit physical contacts with granulosa cells through the follicular basement membrane, and, during the late follicular phase, small dendritic macrophages can be detected among granulosa cells, but not within the follicular antrum. Large antral follicles undergoing atresia exhibit strong pRb expression in granulosa cells. This is accompanied by a lack of Thy-1 differentiation protein among granulosa cells and the occurrence of large phagocytic macrophages in the follicular antrum. This is the first report of pRb expression in the human ovary.(ABSTRACT TRUNCATED AT 400 WORDS)

The Role of Interleukin-6 in the Regulation of Granulosa Cell Apoptosis During Follicular Atresia in Pig Ovaries

“…Cytokines produced by immune cells such as macrophages are involved in various physiological events, such as follicular development, atresia, ovulation, and luteolysis in ovaries [33,34]. Macrophages are present in the ovaries of many animal species, but it has not been clear whether they are located in the theca layer, granulosa layer, or follicular antrum [35][36][37]. In the present study, we clearly demonstrated that macrophages are located only in theca external and internal layers of healthy follicles, and that they are not in the granulosa layer or follicular antrum.…”

Elimination of atretic follicles from the mouse ovary: a TEM and immunohistochemical study in mice

“…This process of atresia is currently regarded as being due to apoptosis, a genetically programmed cell death, of the granulosa cell mass and ultimately of the oocyte (Hughes & Gorospe, 1991 ;Tilly et al 1991). Several authors have claimed that macrophages are active in phagocytosing apoptotic (pyknotic) granulosa cells in atretic follicles in mice (Byskov, 1974) and other animals (Peluso et al 1980 ;Bukovsky et al 1993Bukovsky et al , 1995Kasuya, 1995Kasuya, , 1997.…”

Deneysel tirotoksikoz modelinde sıçan ovaryum dokusu rejenerasyon yeteneği ve kapasitesi

“…Bukovsky (37) tarafından, primer foliküllerde ve çevresindeki stromal hücreler ile vasküler perisitlerde immünoekspresyon gösterilmiştir. Preantral ve antral foliküllerin büyümesinde, aktive makrofajlar ve tekal vasküler perisitlerden Thy-1'in aşırı sekresyonu eşlik eder (38). Menstrüel siklus sırasında bir folikül seçilip dominant hale gelir ve diğerleri atreziye uğrar.…”