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Specific induction of self‐discrimination by follicle cells in Ciona intestinalis oocytes
Author(s) -
Pinto Maria Rosaria,
Santis Rosaria,
Marino Rita,
Usui Noriko
Publication year - 1995
Publication title -
development, growth and differentiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.864
H-Index - 66
eISSN - 1440-169X
pISSN - 0012-1592
DOI - 10.1046/j.1440-169x.1995.t01-2-00006.x
Subject(s) - ciona intestinalis , follicle , vitelline membrane , microbiology and biotechnology , biology , oocyte , human fertilization , ovarian follicle , oogenesis , heterologous , andrology , anatomy , embryo , endocrinology , ovary , genetics , medicine , gene
Self‐incompatibility, a mechanism that prevents self‐fertilization in ascidians, is based on the ability of the oocyte vitelline coat to distinguish and accept only heterologous spermatozoa. In Ciona intestinalis self‐discrimination is established during late oogenesis and is contributed or controlled by products of the overlying follicle cells. In this study we have further investigated the role of the follicle cells in the onset of self‐discrimination by using in vitro maturation of ovarian oocytes deprived of the follicle cells and incubated with either autologous or heterologous follicle cells. Fertilization assays demonstrate that the action of the follicle cells is exerted even when they are detached from the vitelline coat and that only autologous follicle cells can promote the induction of self‐sterility on the egg coat. Electron microscopy of the oocytes during maturation reveals that the switch from self‐fertility to self‐sterility is accompanied by the appearance of a thin electron‐dense layer on the outer surface of the vitelline coat. We suggest that the formation of this layer is the result of the interaction between products of the follicle cells and the autologous vitelline coat.