A quantitative interference light microscope study of human first trimester chorionic villi

Using a Jamin-Lebedeff-type interference microscope an analysis of frozen sections of human first trimester chorionic villi reveals regional differences down to subcellular resolution. The evidence indicates compositional differences between villus cell types and shows that the syncytiotrophoblast is differentiated into at least three layers, one of which corresponds positionally to the previously described syncytioskeletal layer. Quantitative measurements have been made of specimen thickness, refractive index and dry mass of regions in the tissue. Local differences in syncytiotrophoblast have been noted with respect to the content of a population of organelles with distinctive optical properties. These may correspond to stored forms of steroid hormone or their precursors.