Flow cytometric analysis of granulosa cells from developing rat follicles

Abstract

Immature rats were treated with diethylstilboestrol (DES) or pregnant mares' serum gonadotropin (PMSG) and forward angle light-scatter (FALS) and 90 degrees light-scatter (90 degrees LS) signals were used to measure the size and the granularity (internal organization) of the granulosa cells, respectively. The results confirmed the presence of two major populations of granulosa cells in the ovaries of both groups of rats, with the same percentage of larger cells in both treatments (52.3% in DES, 49.5% in PMSG). Since DES treatment brings about granulosa cell growth while PMSG treatment causes growth and differentiation, it is evident that there is heterogeneity in granulosa cell sizes during different states of growth and differentiation. There was also heterogeneity in sizes of granulosa cells harvested from follicles of small (less than 210 microns), medium (210-420 microns) and large (greater than 420 microns) diameter. Quadrant analysis of granulosa cells in various fractions collected from Percoll gradients suggested an increase in granularity in the small and large granulosa cell populations. Cell cycle analysis of small and large granulosa cell populations collected from large follicles of rats treated with PMSG indicated that each population was distributed in G0/G1, S and G2/M phases. These results demonstrate that populations of small and large granulosa cells exist in rat ovarian follicles during various stages of growth and differentiation.

Cellular localization and changes in expression of prolactin receptor isoforms in sheep ovary throughout the estrous cycle

“…In contrast to the scattered loss of short PRLrs, decreased immunoreactivity for the long PRLr primarily occurred in mural granulosa cells, whereas antral granulosa cells were positive for long PRLr until the transition to ovulatory follicle. This finding is in agreement with the lack of PRLrs in mural cells of rat antral follicles (Dunaif et al 1982) and is consistent with the occurrence of two granulosa cell subpopulations that differ in cell sizes and hormonal responsiveness (Rao et al 1991, Sanbuissho et al 1993. During follicular development granulosa cells differentiate into antral and mural cells; antral cells are larger than mural cells, are placed close to the antrum, appear to be involved in the synthesis of estradiol and progesterone, and lose their ability to proliferate earlier than mural cells.…”

Proliferative and steroidogenic capabilities of rat granulosa cells of different sizes

“…These gonadotrophin/growth factor combinations may be able to stimulate mitogenic pathways in large granulosa cells but this remains to be tested. The contention that large granulosa cells may be capable of mitosis is supported by the observation that the same percentage of small and large granulosa cells are observed in the G2-M stage of the cell cycle (Rao et al, 1991b). …”

Functional and ultrastructural characteristics of two types of rat granulosa cell cultured in the presence of FSH or transforming growth factor (TGF- )

“…Rat granulosa cells have been shown to consist of two distinct cell types that can be separated according to size (Telfer et al, 1988; Hartshorne, 1990;Vanderhyden et al, 1990;Rao et al, 1991). Rao et al (1991) consider that the two types of granulosa cell differ in their degree of differentiation, and that this is inde¬ pendent of the cell cycle within the follicle.…”

“…Rao et al (1991) consider that the two types of granulosa cell differ in their degree of differentiation, and that this is inde¬ pendent of the cell cycle within the follicle. The different charac¬ teristics of the two cell types seem to be important for follicular function(s); however, little is known concerning the function of these subpopulations of granulosa cells and whether they are related to the stages of follicular development.…”