β-Glucuronidase in the Rat Placenta

Abstract

HISTOCHEMICAL investigations, using the ferric hydroxyquinoline method of Fishman and Baker¹, indicate that the β-glucuronidase of the fully established rat placenta is predominantly fœtal. As early as the 9-day stage there is moderate activity in the embryonic structures. At 11 days an intense reaction is obtained in the endoderm of the visceral yolk sac, in the trophoblast and giant cells of the central zone and ectoplacental cone and in the endovascular plasmodium growing into the decidual arteries. The activity of the visceral yolk sac remains high, with a terminal drop in the last two or three days of pregnancy. The giant cells, the junctional zone trophoblast and the endovascular plasmodium, with the exception of the glycogen cells, retain a high activity until about the 19th day, but the labyrinthine activity begins to fall off at about 15 days. By the 22-day stage the reaction in all the trophoblastic structures is greatly reduced.