Granulosa Cells Of Corpus Luteum Research Articles

Human mitotic non-luteinizing and non-mitotic luteinized granulosa cells have different sensitivity to chemotherapy agents

Adult human ovary harbors different types of follicles and granulosa cells. Of these, granulosa cells of preantral and early antral follicles are proliferative but are not capable of undergoing luteinization whereas the granulosa cells of corpus luteum are non-mitotic luteinized type. The aim of the current study was to investigate if these two types of granulosa cells differ in terms of their sensitivity to cytotoxic actions of chemotherapy drugs.

Cellular Localization of Inhibin .ALPHA.-subunit, PKB/Akt and FoxO3a Proteins in the Ovaries of Minipigs

Experiments were conducted to examine the cellular localization of inhibin alpha-subunit, protein kinase B (PKB/Akt), and FoxO3a proteins in the ovaries of minipigs, Chinese Xiang pigs, by immunohistochemistry. The results indicated that inhibin alpha-subunits were localized in the granulosa cells of follicles at all stages but were not localized in corpora lutea. PKB was localized in the granulosa cells of primordial follicles and in the basal layers of the granulosa cells of preantral and antral follicles, but were not localized in atretic follicles and corpora lutea. FoxO3a was localized in the granulosa cells of follicles at all stages and was extensively localized in the cytoplasma of the luteinized granulosa cells of corpora lutea. Together, the stage- and cell-specific expression patterns of inhibin alpha-subunit, FoxO3a, and PKB suggest that these proteins might play potential roles in follicular development, atresia, and luteinization in the minipig.

Integrin alpha5 is expressed on human luteinizing granulosa cells during corpus luteum formation, and its expression is enhanced by human chorionic gonadotrophin in vitro.

We previously reported that human granulosa cells (GC) express integrin alpha6beta1, in large follicles and early corpus luteum (CL). In this study, we examined the expression of integrin alpha5 and fibronectin (FN) by immunohistochemistry. Integrin alpha5 was undetectable on human GC in preovulatory follicles, but it was intensely expressed on luteinizing GC of CL in the early luteal phase, and it was weakly expressed on large luteal cells (LL) in the midluteal phase. FN was similarly expressed between GC/LL. Thus, integrin alpha5 and FN were stage-specifically expressed on/between luteinizing GC in the early luteal phase. Next we examined the effect of human chorionic gonadotrophin (HCG) on expression of integrin alpha5 on luteinizing GC in vitro. GC obtained from preovulatory follicles were cultured for 3 days without (control) or with HCG (1 IU/ml), and expression of integrin alpha5 was examined by flow cytometry. Although the positivity rate did not differ, the mean relative fluorescence intensity was 3.4-fold higher in the HCG-treated group (n = 8, P < 0.01). These findings indicate that integrin alpha5 is rapidly expressed on GC during luteinization, probably under LH stimulation, and suggest that integrin alpha5 is involved in CL formation via interaction with its ligand FN.

Selective expression of insulin-like growth factor system components during porcine ovary follicular selection.

In situ hybridization was used to map anatomical patterns of insulin-like growth factor (IGF) system gene expression in the gilt ovary through the estrous cycle. IGF-I, IGF-II< and IGF-I receptor messenger RNAs (mRNAs) were coexpressed in granulosa cells of developing and dominant follicles through the follicular phase. IGF-I and IGF-I receptor mRNAs were selectively concentrated in healthy follicles, whereas IGF-II mRNA was found in all follicles regardless of incipient or overt atresia. IGF-binding protein-1 (IGFBP-1) was not detected in the gilt ovary at any stage. IGFBP-2 mRNA was most abundant in granulosa cells of small follicles and in the ovarian vasculature regardless of cycle stage. IGFBP-2 mRNA persisted in granulosa cells of preovulatory follicles and corpora lutea. IGFBP-3 mRNA was not detected in developing follicles, but was detected in all luteal phase corpora lutea, apparently expressed by theca lutein cells. IGFBP-4 demonstrated a highly dynamic pattern of gene expression, closely tracking LH receptor gene expression throughout the follicular and luteal phases of the estrous cycle. IGFBP-4 mRNA was concentrated in the theca of medium to large growing follicles, but was not detected in granulosa cells until the emergence of dominant follicles in the late follicular stage, when the granulosa cells showed morphological evidence of luteinization as well as LH receptor gene expression. IGFBP-4 mRNA expression continued in granulosa cells of corpora lutea during the luteal phase and was not detected in atretic follicles. IGFBP-5 mRNA was concentrated in the surface or germinal epithelium and in capillary endothelium, particularly in capillaries of corpora lutea. In summary, there is selective expression of IGF-I, IGF-I receptor, and IGFBP-2 and -4 mRNAs during the process of follicular selection in the gilt ovary, with IGFBP-4 expression being closely associated with follicular selection and luteinization. These observations support an important role for autocrine/paracrine IGF action modulated by IGFBP-2 and -4 in both follicular growth and differentiation in the porcine ovary.

Cellular pattern of insulin-like growth factor-I (IGF-I) and IGF-I receptor gene expression in the developing and mature ovarian follicle.

We have employed in situ hybridization histochemistry to map the cellular pattern of insulin-like growth factor-I (IGF-I) and IGF-I receptor gene expression in developing rat ovaries from the time of birth through adulthood, and in response to hypophysectomy and gonadotropin replacement. From the early postnatal period, both IGF-I and IGF-I receptor messenger RNAs (mRNAs) were highly abundant and evenly distributed in granulosa cells of small, growing follicles. In large follicles, however, IGF-I gene expression was heterogeneous. IGF-I mRNA was most abundant in granulosa cells lining the antrum and surrounding the oocyte, but was low or undetectable in mural granulosa cells of Graafian follicles, and was also undetectable in luteinized granulosa cells of corpora lutea. IGF-I receptor mRNA was evenly distributed in developing and mature follicles and was highly abundant in the luteinized granulosa cells of corpora lutea. IGF-I receptor but not IGF-I mRNA was detected in growing oocytes. Hypophysectomy resulted in a decrease and treatment with PMSG resulted in an increase in follicular IGF-I receptor mRNA levels, whereas there was no change in IGF-I mRNA levels in the same protocol. In summary, high levels of both IGF-I and IGF-I receptor gene expression occur in the granulosa cells of actively growing follicles, suggesting that granulosa cell IGF-I may have a role in follicular or oocyte growth. IGF-I gene expression is lost concomitant with follicular enlargement and granulosa cell differentiation, whereas IGF-I receptor gene expression continues at high levels in luteinized granulosa cells, suggesting that IGF effects on differentiated granulosa cell function are due to circulating, not local, hormone. Finally, granulosa cell IGF-I receptor gene expression appears to be regulated by the gonadotropin present in pregnant mare serum.

Binding proteins for insulin-like growth factors in the human ovary: identification, follicular fluid levels and immunohistological localization of the 29–32 kd type 1 binding protein, IGF-bp1

The occurrence of pregnancy-associated endometrial alpha 1-globulin (alpha 1-PEG), a 29-32 kd insulin-like growth factor binding protein, now termed type 1 or IGF-bp1, has been examined in the human ovary by monoclonal and polyclonal antibody based radioimmunoassay and immunohistological techniques. Follicular fluids aspirated from 51 follicles of 32 women undergoing hyperstimulation involving buserelin or clomiphene-based protocols contained 35.5-276.0 ng/ml (mean 101.0 mg/ml) of immunoreactive IGF-bp1. Mean fluid concentrations were three times the level of IGF-bp1 detected in paired serum samples, available for 21 women. Immunoreactive IGF-bp1 in follicular fluid exhibited similar dose-response curves to purified protein and amniotic fluid and immunoreactive IGF-bp1 coeluted in gel filtration with a peak of [125I]-IGF-1 binding corresponding to the elution profile of purified IGF-bp1. Gel filtration also revealed the presence in follicular fluid of a greater than 100 kd binding protein with a binding capacity equal to IGF-bp1 under the conditions employed. A highly significant correlation (P less than 0.001) was found between follicular fluid progesterone and IGF-bp1 and a correlation of lower significance was found between oestradiol and IGF-bp1 (P less than 0.05). However, only low levels of immunoreactive IGF-bp1 were detected in supernatant media of granulosa cells in culture (range undetectable to 2.3 ng/ml). Employing monoclonal antibody-based immunohistology, immunoreactive IGF-bp1 was consistently associated with luteinized granulosa cells of corpora lutea rather than paraluteal cells and its intensity of reactivity appeared to reflect luteal phase steroid hormone profiles. No consistent reactivity was detected in preovulatory follicles and granulosa cells in culture, although reactivity was associated with primordial oocytes. Immunoreactive IGF-bp1 was detected in six of nine supernatant media of explants of luteal tissue obtained from five corpora lutea, with levels ranging from undetectable to greater than 200 ng/ml. These observations suggest that IGF-bp1 is primarily related to luteinization of the granulosa and the resultant luteal cells, and if produced by the luteal cells, additional exogenous factors are required to induce production by granulosa cells in vitro.

Luteoma of pregnancy: Ultrastructural features

The ultrastructural configuration of the cells in one case of pregnancy luteoma was studied by conventional electron microscopy. The fine structure of these cells conforms closely to that of steroid hormone producing cells in other human organs, such as the adrenal cortex, testicular interstitium, and corpus luteum, particularly in terms of the presence of abundant smooth endophasmic reticulum, dispersed Golgi apparatus, and tubular cristae in the mitochondria. Similarities were noted between the pregnancy luteoma cells and, as described by other authors, the luteinized granulosa and theca cells of the human corpus luteum and the cells of spontaneous mouse luteoma. There was a more pronouced resemblance to the granulosa cells of the corpus luteum than to the luteinized theca cells or the mouse lutcoma cells but with considerable overlap among all of them. Distinctive features, not previously described, were noted in the pregnancy luteoma cells in the form of deep cytoplasmic invaginations of the cell membrane closed by tight junctions, and peculiar pleated sinuous membranous arrays within the cytoplasm. The significance of these structures is not known. In addition mesenchymal cells of ambiguous differentiation were noted in the stroma of the tumor, suggesting that the stimulus to luteinized cell proliferation may transcend the specific ovarian mesenchymal cells and may also be exerted on the supporting stroma. On the basis of previous reports concerning the biochemical and biosynthetic patterns of sex steroid hormone production by these tumors, it is concluded that although the latter recapitulate the endocrine functions of the normal ovarian stroma rather than those of the corpus luteum, the cytoarchitecture of these tumors covers a much broader spectrum of differentiation, which may come to resemble closely although not exclusively that of luteinized granulosa cells.