Glycomic analyses of ovarian follicles during development and atresia

Abstract

To examine the detailed composition of glycosaminoglycans during bovine ovarian follicular development and atresia, the specialized stromal theca layers were separated from the stratified epithelial granulosa cells of healthy (n = 6) and atretic (n = 6) follicles in each of three size ranges: small (3–5 mm), medium (6-9 mm) and large (10 mm or more) (n = 29 animals). Fluorophore-assisted carbohydrate electrophoresis analyses (on a per cell basis) and immunohistochemistry (n = 14) were undertaken. We identified the major disaccharides in thecal layers and the membrana granulosa as chondroitin sulfate-derived ∆uronic acid with 4-sulfated N-acetylgalactosamine and ∆uronic acid with 6-sulfated N-acetylgalactosamine and the heparan sulfate-derived Δuronic acid with N-acetlyglucosamine, with elevated levels in the thecal layers. Increasing follicle size and atresia was associated with increased levels of some disaccharides. We concluded that versican contains 4-sulfated N-acetylgalactosamine and it is the predominant 4-sulfated N-acetylgalactosamine proteoglycan in antral follicles. At least one other non- or 6-sulfated N-acetylgalactosamine proteoglycan(s), which is not decorin or an inter-α-trypsin inhibitor family member, is present in bovine antral follicles and associated with hitherto unknown groups of cells around some larger blood vessels. These areas stained positively for chondroitin/dermatan sulfate epitopes [antibodies 7D4, 3C5, and 4C3], similar to stem cell niches observed in other tissues. The sulfation pattern of heparan sulfate glycosaminoglycans appears uniform across follicles of different sizes and in healthy and atretic follicles. The heparan sulfate products detected in the follicles are likely to be associated with perlecan, collagen XVIII or betaglycan.

Involvement of hyaluronan synthesis in ovarian follicle growth in rats

“…corpora lutea (Laurent et al 1995). Similar HA reduction is observed in the granulosa cell layer of antral follicles under atresia (Salustri et al 1999, Hatzirodos et al 2012). …”

“…Indeed, cumulus expansion, HA accumulation associated with a dramatic morphological dynamism, is utilized as a marker of human oocyte maturation in assisted reproductive technology and is known to be required for normal in vivo ovulatory and subsequent fertilization processes in mammals and thus its concentration seems to be appropriate. On the other hand, glycosaminoglycans other than HA are known to be expressed in small growing follicles and play roles in folliculogenesis (Irving-Rodgers et al 2010, Hatzirodos et al 2012. HA accumulation in small preantral follicles of WT and Hyal1-null mice has recently been revealed (2008) showed that Hyal1, Hyal2, and Hyal3 are expressed in the preantral/antral follicles of immature mice, which reflects the existence of HA in these follicles.…”

“…As has been described above, most of the ovarian HA research has focused on the accumulation in the cumulus cells of preovulatory antral follicles, but not on the production in small growing preantral follicles or the developing ovary, even though ECM constituents other than HA such as collagens, laminin, proteoglycans, and sulfated glycosaminoglycans are localized in small preantral follicles and play roles in folliculogenesis (Irving-Rodgers et al 2010, Hatzirodos et al 2012. A histological study carried out by Dumaresq-Doiron et al (2011) has illustrated HA expression in the growing preantral follicles of WT and Hyal1-knockout mice for the first time.…”

Development of mammalian ovary

“…In newborn mice, Honda et al (2007) isolated a population of putative thecal stem cells. Hatzirodos et al (2012) also provided evidence for clusters of putative thecal stem cells in the adult bovine ovary based on the localization of proteoglycans generally associated with stem cell niches. Further evidence comes from differences in the morphology of the rete ovarii in a sheep model for PCOS ).…”

Mechanisms of fibroblast growth factor signaling in the ovarian follicle

“…Perlecan mRNA levels change during follicle development (Matti et al 2010), and HSPG levels within the granulosa cell layer, likely in focimatrix, are significantly higher in atretic compared with healthy follicles (Huet et al 1997, Irving-Rodgers et al 2004, Matti et al 2010. Further, follicle HSPG is sulfated and, at least in the cow, the quantity of certain sulfated HS derived saccharides change during follicle development and atresia (Hatzirodos et al 2012). Therefore the potential for regulation of FGF signaling by follicular HSPGs exists.…”