Abstract
Alkaline phosphatase (AP) activity in the placenta was investigated histochemically in relation to the characteristic patterns of the heat-stable alkaline phosphatase (HSAP) in the serum of near-term women, which were classified in the previous report into four, i.e., elevating, descending, flattening (plateau), and fluctuating (unstable). Most of the women who appared entirely normal and showed either elevating or descending pattern in their HSAP activity, maintained a steady activity of AP in the chorionic epithelium of the placenta. On the contrary, most of the cases which are conceived as abnormal and showed fluctuating pattern in the HSAP activity revealed a decreased activity of AP in chorionic epithelium. Such decrease in the placental AP activity was observed predominantly in postdated women with the fluctuating pattern, but such relationship between AP activity in the placenta and the pattern of HSAP was less evident in cases with pregnancy toxemia.
