Luteal phase endometrial cytosol and nuclear progesterone receptors in infertile women.

Progesterone receptor (PR) concentrations in cell nuclei (PRn), in cytosols (PRc) and a percentage of PRn, plasma progesterone level (P) and histological endometrium dating in the secretory phase of the menstrual cycle were studied in three groups of patients. In the control group (group "A"-17 patients) there were infertile patients with normal levels of plasma P and histological dating of the endometrium corresponding to the actual day of the menstrual cycle. In group "B" (7 patients) there were infertile patients with normal plasma P levels and delayed histological finding of the endometrium for 2 or more days (mean 3.3 days)--"pseudocorpus luteum insufficiency". In group "C" there were 3 patients with delayed secretory transformation of the endometrium and low plasma P level (luteal phase defect). In group "B" there was lower concentration of the total PR (for 305.5 fmol/mg DNA), PRc (for 536.8 fmol/mg DNA), higher concentration of PRn (for 233.4 fmol/mg DNA) and for 20.5% higher percentage of PRn, but these values are not significantly different from those in the control group. In group "C" there were higher concentrations of the total PR and percentage of PRn but the sample was too small to permit statistical comparison. On the basis of these results we cannot conclude if in "pseudocorpus luteum insufficiency" a decreased sensitivity of the endometrium is due to the P, or is functional in nature. It will be necessary to continue our work on a larger number of patients and also to study changes in PR concentrations in the follicular phase of the menstrual cycle.