Cytochemical establishment of acid phosphatase in the bovine endometrium and trophoblast during implantation.
Acid phosphatase in the endometrial surface epithelium is seen in connection with autophagy and autolysis. In the precontact and initial apposition stage, enzyme-positive Golgi vesicles, lysosomes and secretion granules all indicate autophage performance of the dark uterine epithelial cells in the sense of a histiogene embryotrophe development. At the time of progressing apposition this is joined by cell degradation with the aim of histiolytical uterine milk production. Following the completed implantation in the adhesion phase no activity with autophagy and autolysis-correlated acid phosphatase can be established. In trophoblast giant cells the localisation of acid phosphatase speaks for secretional processes. The incidence of this enzyme in the adhesion stage in "ordinary" trophoblast cells leads to the supposition of autophage processes which must be investigated in more detail. The endometrial gland epithelium shows the same acid phosphatase-dependent autophage indications in the upper third of the glands as shown in the surface epithelium prior to apposition. However, the acid phosphatase activity and the secretion deduced therefrom, thus the histiogene embryotrophe development, is conserved during the whole early gravidity of the cow, independent of the implantation process.