Histological and hitochemical studies on human fetal membranes

1. In the stage later than the middle stage of pregnancy, morphological differences appear between the amniotic epithelial cells of placenta and those of the free part and the majority of cases the amniotic epithelial cells of placenta present more marked columnar shape than those in the surrounding area of ruptured orifice or those in the vicinity of placenta. However, there still remains a question whether or not such a phenomena is directly related to the secretory function of the placenta amniotic epithelium. 2. It seems that amniotic epithelial cells divide and multiply themselves by mitosis at least in the early and middle stages when their functions are at height. 3. Even in the stage later than the middle stage generally the amniotic epithelium of placenta is consisted of a single layer of columnar epithelial cells, and therefore, the author cannot agree to Forssell's theory. 4. In glycogen and lipid stainings, the amniotic epithelial cell layer shows more striking changes with the progress of gestational month when compared with those cells in other layers. 5. Glycogen in the amniotic epithelial cell layer is abundant in the early and middle stages of pregnancy, and it rapidly decreases near the late stage. Lipid granules on the contrary are less in the early stage, and start to appear in the middle stage, increasing rapidly towards the late stage. In general, the regressive degeneration picture of the late stage is not distinct histologically, but assuming glycogen to represent the cell activity and the lipid deposit to mean just the reverse, the amniotic epithelium functionally seems to fall into regressive degeneration from the middle stage. Other layers of fetal membranes likewise undergo fatty degeneration as the pregnancy progresses from the middle stage to the late stage. 6. There still remain problems to be solved on the question what role this regressive degeneration of the amniotic epithelial cell layer plays in de Watteville's theory, "Labor originates from the fetal membranes". However, granular PAS-positive substances in the amniotic epithelium are glycogen, and it seems difficult to connect simply the existence or non-existence of PAS-positive granules or Sudan-positive granules directly with the continuation or interruption of pregnancy.