Detection of sperm antigens on mouse ova and early embryos

Abstract

Serum and colostrum antibodies against mouse sperm were developed in two rabbits after systemic and mammary gland immunizations. Indirect immunofluorescence utilizing fluorescein-labeled goat antisera against rabbit IgG and IgA, respectively, indicated that both immune serum (IS) and colostrum (IC) compared with control samples caused intensive staining of the acrosome and tail of sperm. Absorption of IS and IC with mouse serum and the spleen, kidney, liver, and brain of male mice did not reduce the strength or the pattern of staining reaction on sperm. The absorbed IS reacted with cell surfaces of oocytes, unfertilized ova, zygotes, two-cell and four- to eight-cell fertilized ova, and blastocysts. The absorbed IC, however, reacted only with the four- to eight-cell embryo and blastocyst. Further absorption of the IS with mouse ovary removed the reaction with unfertilized ova and the one- to two-cell fertilized ova, but the staining of later embryo stages was unaffected. Therefore, it appears that specific rabbit anti-sperm antibodies are detecting two cell-membrane antigens on mouse embryos: one originating from the ovary and the other arising after fertilization.