Spectrin in mouse gametogenesis and embryogenesis

Antibodies to nonerythroid alpha spectrin (p 230) were used to study the distribution of this polypeptide in mouse germ cells, zygote, and early embryonic cells. In the primordial germ cells, fetal oocytes, and spermatogonia, spectrin was found predominantly in the form of a narrow condensed subplasmalemmal band, as in all other somatic cells. During spermatogenesis, spectrin is condensed into the supraacrosomal cytoplasm and is lost during the reduction of the cytoplasm of the maturing spermatozoa. The postnatal growth of the oocyte is accompanied by a loss of the dense cortical band of spectrin and its redistribution in the cytoplasm. Zygotes also contain granular dispersed spectrin. Cortical condensation of spectrin filaments gradually reappears in the blastomeres at the two-cell stage and in the secondary polar body. Cortically condensed filaments represent thereafter the predominant form of spectrin in all preimplantation stage embryonic cells. Trophoblastic cells spreading out from explanted blastocysts are devoid of the cortically condensed spectrin and contain, instead, spectrin arrays in the cytoplasm. Trophoblastic cells, which surround the implanted embryo in vivo, also show diffuse cytoplasmic spectrin which subsequently undergoes subplasmalemmal condensation. These data show that spectrin is present in all stages of gametogenesis and embryogenesis, except in mature spermatozoa; and that it undergoes cytoplasmic redistribution during morphogenesis.