The endometrial surface is required to reject attachment of exogenous undesirable substances such as pathogens, while occasionally shifting properties to allow physical interaction with an embryo to support a successful pregnancy. Kubota et al. reported that MUC1, a potent inhibitor of cellular contact via its large extracellular glycoprotein domain, localizes to the apical surface of bovine endometrium (upper panel, green staining). This MUC1 barrier can be removed in response to steroid signaling at receptive phase and during pregnancy (lower panel), as revealed by immunohistochemistry (p. 386–391). Red signal (pseudo-color) represents DAPI-stained nuclei. Interestingly, MUC1 expression is elevated in the endometrium of cows with a long postpartum interval, which is a known risk for reducing female fertility. Thus, this observation is consistent with the proposed anti-attachment role of MUC1. These results suggest that MUC1 regulation plays a role in endometrial homeostasis and embryo implantation, and its negative correlation with fertility may be used as a diagnostic of reproductive efficiency.
Bidirectional communication between oocytes and granulosa cells or cumulus cells is maintained through transzonal projections (TZPs). These structures are important for oocyte growth, although the mechanism underlying TZP development remains unclear. Fushii et al. demonstrated the disappearance of TZPs by denudation of bovine growing oocytes and the reestablishment of TZPs by coculture of TZP-free denuded oocytes (DOs) with mural granulosa cells (MGCs) (Fushii et al. pp. 300–306). Twenty-four hours after denudation, almost all TZPs disappeared, and after coculture and subsequent growth culture of DOs with MGCs, TZPs were reestablished (upper). Additionally, the oocytes in reconstructed complexes grew fully and acquired meiotic competence, suggesting that the reestablished TZPs are able to support oocyte growth similar to those in cultured oocyte-cumulus cell-mural granulosa cell complexes (middle) and in vivo grown oocytes (lower).
During oocyte growth and follicle development, oocytes closely communicate with cumulus cells. Morikawa et al. examined the effects of oocyte-derived growth factors, growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15), on the growth and acquisition of meiotic competence of porcine oocytes (Morikawa et al. pp. 273–281). Oocyte-cumulus cell complexes (OCCs) collected from early antral follicles were cultured in growth medium supplemented with GDF9 (upper left) and BMP15 (upper right) for 5 days. Only GDF9 increased the OCC diameter in a dose-dependent manner. OCCs that had been cultured with GDF9 or BMP15 were subjected to a subsequent maturation culture. Those OCCs cultured with GDF9 expanded loosely (lower left), whereas those with BMP15 expanded fully and matured to the second metaphase (lower right).
公開日: 2010/10/20 | 43 巻 6 号 p. j19-j25
岡部 勝, 伊川 正人, 山田 秀一, 中西 友子, 馬場 忠
Follicular Growth and Atresia in Mammalian Ovaries: Regulation by Survival and Death of Granulosa Cells
公開日: 2012/03/22 | 58 巻 1 号 p. 44-50
Fuko MATSUDA, Naoko INOUE, Noboru MANABE, Satoshi OHKURA
Monitoring Metabolic Health of Dairy Cattle in the Transition Period
公開日: 2010/08/10 | 56 巻 S 号 p. S29-S35