Abstract
Examination of chorionic villi from rhesus monkey placenta revealed the presence of C-type virus particles budding from syncytial trophoblast, pericytes, Hofbauer cells, and mesenchyme. In addition, particles, were found budding from cells of the cytotrophoblastic cell column and decidual basalis. They measured 30 nm in diameter, had a dense central core, surrounded by a narrow, electron-lucent zone, and were enclosed by an outer unit membrane.