Acid phospatase (AcPase), alkaline phosphatase (AlPase), 5'-nucleotidase (AMPase), Mg-activated adenosine triphospatase (ATPase), thiamine pyrophospatase (TPPase) and glucose-6-phospatase (G6Pase) were investigated in the human corpus luteum of early pregnancy using a cerium-based method in combination with a microslicer.
Ultrastructurally, cerium phosphate reaction product appears as a very fine electron dense precipitate. The AcPase reaction products were exclusively localized in the lysosomes and in two cisternae of the Golgi lamellae on the trans-side. The AlPase and AMPase reaction products were observed in the plasma membrane. The Mg-activated ATPase reaction products were found in the matrix of the mitochondria as well as in the plasma membrane. The TPPase reaction products were present in two cisternae of the Golgi lamellae on the trans-side. The G6Pase reaction products were found in the rough endoplasmic reticulum. This technique can be applied routinely for the demonstration of phosphatase activity because of its reproducibility and specificity when cerium is used as the capturing agent, and yields better results than the lead-based method. In the luteal cells, these several phosphatases might serve to maintain a constant metabolic activity in the early pregnancy.