X-ray micro analyses of cations (Na, K, Ca) and anions (S, P, Cl) in uterine secretions during blastocyst implantation in the rat.

The mass changes of sodium, potassium, and calcium ions in the rat uterine secretion at blastocyst delay, activation, and attachment have been estimated with X-ray microanalyses of samples of uterine secretions absorbed by small Sephadex beads. A quantification of the ions was attempted by using a standardized coat of gold on the beads as a reference element for normalization of the ion peaks and by fitting the normalized values into corresponding linear regression equations obtained from measurements of step-wise dilutions of a control rat serum. The concentrations of sodium observed at delay, activation, and attachment were 117, 201, and 203 mEq/l, respectively, and those of potassium were 6, 18, and 19 mEq/l, respectively. Calcium values were about 2 mEq/l and decreased at attachment. Among the anions, only the chloride concentration increased at activation and attachment.