DISAPPEARANCE OF HISTOCHEMICALLY-DEMONSTRABLE ADENOSINE TRIPHOSPHATASE AND OF PAS-REACTIVE BASEMENT MEMBRANES IN BLOOD VESSELS IN THE DECIDUA DURING OVUM IMPLANTATION IN MICE

Abstract

SUMMARY Histochemical studies were made of the endometrial blood vessels before and after normal implantation of blastocysts in intact mice and delayed implantation in pregnant, spayed, hormone-treated mice. Adenosine triphosphatase (ATPase) activity was investigated by the calcium method of Padykula and Herman and the lead method of Wachstein and Meisel, controlled by inclusion of inhibitors and by substitution of other substrates. Paraffin sections were subjected to the periodic acid-Schiff (PAS) technique. In the endothelium of endometrial blood vessels intense ATPase staining occurred on days 2 to 5 in intact mice and until at least day 9 in spayed mice injected with progesterone alone (no implantation), and in the non-decidual areas after normal (day 6) or induced (days 7–9) implantation. The reaction appeared to be localized in the endothelial plasma membranes, mainly in the basal membrane. The basement membranes of these vessels reacted strongly with PAS. Within decidual tissue at the implantation sites in both intact and spayed mice ATPase activity was completely absent from all blood vessels. The basement membranes of these vessels gave no reaction with PAS. There was close correlation in distribution and time of appearance between absence of ATPase activity and differentiation of alkaline phosphatase-reactive decidual cells. The specificity of the vascular reaction with ATP is considered in the light of its behaviour towards enzyme inhibitors and other substrates, and the significance of its disappearance in decidual blood vessels is discussed.