Experimental rat choriocarcinoma: an electron microscopic study.

Experimental choriocarcinomas of the rat were studied with electron microscopy and compared with the ultrastructure of rat trophoblasts at mid-and late-gestational stage. The choriocarcinoma numbered m-803 contained abundant cytoplasmic organellae and was quite similar to the trophospongial cell at late-gestational stage. The M-801 closely resembled the trophospongial cell at mid-gestational stage. The m-673, which has 3-beta-ol dehydrogenase enzyme system, could not be studied sufficiently inspite of the examination of more than 30 blocks of epon embedded specimen, because of the degeneration and necrosis occurring in the specimens.