Periderm week 8

By the eighth week of embryonic development, periderm cells are studded with microvilli, many of which extend into the amniotic fluid.

The blue-staining material appearing as a haze around the pericytes is micropolysacharide and microvilli. Microvilli are too small to be resolved with a light microscope. The PAS stain used on this specimen stains glycogen reddish-purple. Note the reddish-purple areas in the cytoplasm of the pericytes and heratinocytes and compare this image to the transmission EM image below.