Coexpression of cytokeratin and vimentin in mice trophoblastic giant cells

Trophoblastic giant cells reach their maximum size and exhibit a conspicuou s synthetic and invasive activity during mouse placentation, The cytoskelet on, given the complex functions of the cells, shows a well-developed networ k of intermediate filament proteins. Immunohistochemistry combined with con focal and conventional immunofluorescence studies of intermediate filaments proteins cytokeratin and vimentin were performed in mice trophoblastic gia nt cells on days 9-11 of pregnancy. Specimens were fixed in phosphate-buffe red formaldehyde and tissues were processed for routine paraffin embedding. Trophoblastic giant cells from antimesometrial, lateral or mesometrial ute rine regions, through days 9-11 of pregnancy, expressed the same staining w ith both immunoperoxidase and immunofluorescent techniques. Cytokeratin fil amentous structures were intensely immunoreactive and were detected through out the cells cytoplasm; a few cells exhibited strongest fluorescence in th e peripheral cytoplasm, Vimentin-positive staining was often distributed th roughout the cells cytoplasm, most frequently and more intensely in the per ipheral region; in some cells, it was present only in the peripheral region s. It is probable that expression of vimentin in midpregnancy trophoblastic giant cells may be associated with the rapid and conspicuous increase in s ize and synthetic activity of the cells and also with phagocytosis of degra ded materials and invasion of decidual tissue. (C) 2001 Harcourt Publishers Ltd.