Changes of human placental alkaline phosphatase and acid phosphatase in prolonged pregnancy

ABSTRACT

The current study aims to investigate the pattern of distribution of alkaline and acid phosphatases in the placentas of prolonged pregnancies compared to that in those delivered at term. In addition, it also aims to determine whether the studied enzyme changes of prolonged pregnancy placentas represent a continuum that may begin before 42 week's gestation. This study examined placentas obtained from 220 non-hypertensive, non-diabetic, non-smoker, Rh[+] singleton pregnant women who delivered at Al-Batool Maternity Teaching hospital in Mosul city in over a period of two months extending from August 1[st] to September 30[th] 2005. These women were classified according to their accurately assigned gestational age into three groups Group 1; includes women who delivered between 38-41 weeks of gestation [n=100], Group 2; includes women who delivered between 41-42 weeks of gestation [n=60], and Group 3; includes those who delivered beyond 42 weeks [n=60]. All placental sections of the three study groups were stained using alkaline phosphatase stain [Gomons method-cobalt] and acid phosphatase stain [Gomons method-lead]. The placentas of group I showed a moderate to marked reaction to alkaline phosphatase stain in the syncytiotrophoblasts with a very weak reaction in the villous stroma, and a moderate reaction in the maternal decidua; however, they showed a very weak reaction to acid phosphatase stain in both syncytiotrophoblasts and the villous stroma. Placentas in group 2 and 3 showed a marked reaction to alkaline stain in the syncytiotrophoblasts, while the villous stroma and the maternal decidua showed a moderate reaction with further decrease in the activity of acid phosphatase in both syncytiotrophoblasts and the villous stroma. Negative reaction to acid phosphatase stain was noticed in the maternal decidua in all groups. Prolonged pregnancy placentas showed increased alkaline phosphatase activity and reduction in acid phosphatase activity. In addition, the studied placental enzyme changes of prolonged pregnancies [including alkaline phosphatase and acid phosphatase] represent a continuum that may begin before 42 weeks gestation as most of these enzymatic changes are associated with pregnancies extended between 41-42 weeks