The distribution and intensity of reaction for adenosine-5′-monophosphatase, adenosine-5′-triphosphatase, inosine-triphosphatase, thiamine-pyrophosphatase, uridine diphosphatase, β-glycerophosphatase and glucose-6-phosphatase were studied in relation to the implanting rat embryo and developing decidua at 3½, 4½, 5, 5½, 6, 6½, 7½, 8½ and 9½ days of pregnancy. The distribution of glycogen was also studied from 4½ days onwards, using the pas procedure in combination with diastase and/or dimedone blockade.
Glycogen was demonstrated in the stroma antimesometrial and lateral to the embryo, accumulating at 6 to 6½ days and gradually being compressed laterally by the expanding decidua, the lateral part of which also contained some glycogen.
All of the enzymes studied accumulated to a greater or lesser degree in the stroma initially and then in the antimesometrial decidua, where their accumulation was paralleled by a falling off of glycogen concentration.
Significant differences in distribution, particularly in the mesometrial region, were noted, adenosine-5′-monophosphatase, uridine-diphosphatase, and glucose-6-phosphatase accumulating in the cells of the glycogen wings, while the remaining enzymes did not. Adenosine-5′-triphosphatase, thiamine pyrophosphatase, and inosine-triphosphatase accumulated in the cells lining the sinusoids of this region.
Adenosine-5′-triphosphatase was the only enzyme studied to show any alteration between 3½ and 4½ days, and it is suggested that the observed antimesometrial accumulation of this enzyme may be a reflection of the oestrogen surge which occurs at this time.
An attempt is made to correlate the presence and alteration in distribution of these enzymes, and of glycogen, with what is known of their physiological functions with respect to glycogen metabolism, energy production, transport of substances across the cell membrane, and nutrition of the embryo.