Ultrastructure of Human Amniotic Fluid Cells in Late Pregnancy

Abstract

Samples of amniotic fluid obtained by amniocentesis during the last trimester of pregnancy were investigated by electron microscopy, disclosing the presence of cells originating from fetal ectodermic structures at various stages of maturation. The majority of the cells recovered from the earliest specimens showed ultrastructural features compatible with those of periderm cells. As pregnancy progressed, the cells underwent keratinization with subsequent reduction of viable organelles. At term, the cellular component of amniotic fluid consisted of homy cells dispersed among aggregates of dense granular material suggestive of the structure of keratohyalin. In one sample, clumps of cells from the stratum germinativum and intermedium of the fetal epidermis were observed. Cells derived from the amniotic epithelium itself could not be identified with certainty.