Electron microscopy of particles similar to type-C virus in human oocytes.

Human oocytes in different stages of maturation were obtained by follicular aspiration from women given Clomovid and Gonadex. Particles similar to type-C virus were observed in 3 out of 16 oocytes. The particle were irregularily distributed along the oocyte membrane. They were seen both in a state of budding and as free lying in the perivitelline space. Reverse transcriptase activity was detected in 3 out of 9 samples of follicular fluid obtained from women other than those yielding the oocytes. It is assumed that these findings indicate the expression of endogeneous retroviruses in human oocytes.