[Histoenzymologic modifications of placental tissue in experimental fetal hypotrophy in the rat].

Chronic placental vascular insufficiency in the rat was achieved by ligature of the uterine and utero-placental arteries. The fetal and placental hypotrophy observed confirmed the previous observation. However, the placental enzymatic changes showed an increasing gradient of cellular hypoxy from decidua basalis to yolk sac placenta; this gradient is unfavourable to fetuses. The strong depletion of yolk sac enzyme activities demonstrates the reduction of fetomaternal exchanges which are usually predominant in this placental area. The other parts of rat placenta appear relatively less involved in fetal nutrition. Further studies are necessary to understand the changes observed in these activity stainings, such as: oxidoreductases II, acid phosphatase and 5-nucleotidase.