FATE OF SPERM ORGANELLES DURING EARLY EMBRYOGENESIS IN THE RAT

This report is part of a continuing study in which we employ monoclona l antibodies to membrane domains and internal organelles of rat sperma tozoa in order to trace events during maturation, capacitation, fertil ization, and early development. In the present study, we have used imm unocytochemistry at the light and EM levels to localize one antibody, 5A5, to the fibrous sheath and a second, 3D5, to the outer mitochondri al membrane. Antibody 5A5 does not stain the fibrous sheath of spermat ozoa of rodents other than the rat, while 3D5 can be localized to the outer mitochondrial membrane of rat, hamster, and mouse spermatozoa. I n order to follow these antibodies during fertilization and early embr yogenesis, we developed a method to stain internal components of zygot es and early embryos. Our findings suggests that the fibrous sheath di sappears prior to the first cleavage and that mitochondria can be dete cted up to the 2-cell stage in mouse and the 4-cell stage in rat. (C) 1994 Wiley-Liss, Inc.