Differential distribution of gangliosides in adult rat ovary during the oestrous cycle

Gangliosides are ubiquitous membrane components in mammaliancells and are suggested to play important roles in various cellfunctions, such as cell-cell recognition, differentiation andtransmembrane signalling. Rat ovary contained GM3, GD3 and GD1aas major gangliosides, and GM1 as a minor one. In order to studytheir distribution in the rat ovary and its possible changesduring the oestrous cycle, frozen sections were stained withspecific monoclonal antibodies against 11 ganglio-series gangliosidesincluding those mentioned above. GM3, GM1 and GD1a were expressedin a spatiotemporally different manner during the oestrous cycle,but GD3 and other gangliosides were not immunohistochemicallydetected. In primary and secondary follicles, GM3, GM1 and GDlawere expressed in theca cells, but not in granulosa cells. Theoocyte in primary, but not secondary, follicles was positiveto the anti-GD1a antibody. In Graafian follicles, GM1 and GD1awere similarly expressed as in secondary follicles, however,the expression of GM3 spread gradually from theca cells to granulosacells. In early Graafian follicles, only GM3 was expressed toa detectable extent from the outer part of the granulosa layerto the inner part Shortly before ovulation, all granulosa cellsand cumulus cells became positive to anti-GM3 antibody. Afterovulation, differential distribution of GM3, GM1 and GD1a wasalso observed in luteal cells. GD1a was localized in thread-likestructures, while GM3 was distributed throughout the cytoplasm,but not in the nucleus. GM1 was localized only in the plasmamembrane and/or its close vicinity. Other ganglio-series gangliosides,including GD3, were not detected to an appreciable extent inthe ovaries by immunohistochemistry ganglioside oestrous cycle rat ovary