Fertilization and early embryology: Nuclei number in human embryos co-cultured with human ampullary cells

Abstract

A study was undertaken to evaluate the effect on nuclei number in human embryos cultured in vitro with primary cell lines of human Fallopian tube epithelium. The development of 203 surplus human embryos, cultured in standard culture medium (Earle's balanced salt solution + 15% A5) with or without ampullary cells, was observed from day 2 to day 5.5 post-insemination. The expanded blastocysts in both culture conditions were analysed for nuclei numbers per blastocyst. Embryos transferred to co-culture at the 2-cell stage had an average of 120.7 nuclei per blastocyst, which was significantly higher than the average of 62.9 nuclei per blastocyst (P = 0.023) for the embryos transferred to co-culture at the 4-cell stage. The embryos cultured in the control medium had an average of 42.1 nuclei per blastocyst, which was significantly less than co-cultured embryos (P = 0.04). Severely fragmented embryos (grades 3 and 4) did not show recovery in co-culture. Our results show that when human embryos are transferred to co-cultures before the 4-cell stage, the blastulation rate and the cell number per embryo increase significantly compared to the embryos cultured in standard culture medium. The possible effect of co-culture on embryonic gene expression is discussed.

Oviduct: roles in fertilization and early embryo development

“…Co-culture of human embryos with the Fallopian epithelia improved the quality of embryos (Yeung et al 1992, Vlad et al 1996. However, analysis in humans suggested that simply mimicking the in vivo environment using an in vitro model did not increase the baby delivery rate (Stern et al 2009).…”

Growth factor expression and function in the human and mouse preimplantation embryo

“…Following IVF, co-culture of human embryos on monolayers of epithelial cells has been shown to increase blastocyst formation (Menezo et al 1990) and blastocyst cell number (Vlad et al 1996). This is thought to be due either to the removal of embryotoxic substances from the medium, or by the secretion of factors that enhance development.…”

Identification of cellular isoform of oviduct-specific glycoprotein: role in oviduct tissue remodeling?

“…Of the several functions attributed to myosin/actin, those relevant to gametes and their physiological environment, namely the oviduct, are: cell shape, motility, acrosome reaction, egg activation, and cytokinesis. These membrane-related events are mediated by the cytoskeleton and calcium ion concentration (Moreno-Fierros et al 1992;Murray and Messinger 1994;Maciver 1996;Kim et al 1996;Vlad et al 1996;DiMaggio et al 1997;Breitbart and Spungin 1997;Barnett et al 1997;Simerly et al 1998;Matsumoto et al 1998;Wang et al 1999;Hernandez-Gonzalez et al 2000;Terada et al 2000), and hence, we might speculate that a fallout of the OGP-myosin interaction would modulate downstream biological effects, possibly through changes in the internal calcium ion concentration. One of the known effects of actomyosin and the internal calcium ion concentration is the disassembly of the AJC in tissue remodeling of epithelia; here, non-muscle myosin IIA, together with actin through the cadherin-catenin pathway, acts as a mechanosensor with regard to changes in cell shape, polarity, and morphogenesis (Conti et al 2004;Castillo et al 1998;Gumbiner 1996;Ivanov et al 2004Ivanov et al , 2005Nelson and Chen 2003).…”