[Endometrial implantation window in infertility]

The paper presents the results of biopsy and curettage specimens from 92 patients with infertility. Histological and immunohistological (steroid receptors, Ki67, P27, and cyclin E) methods and scanning electron microscopy have been used. The substantial immunohistochemical (IHC) changes found in the endometrial implantation window in infertility are associated with the spectrum of the detected pathology. No clear correlations between the expression of IHC markers and the concentrations of serum hormones, which are characteristic of the normal menstrual cycle, may suggest that there is an imbalance of steroid reception at the endometrial tissue level. The detection of proteins P27 and cyclin E in the cytoplasm of glandular and stromal cells reflects the deficient block of a cell cycle essential for an adequate implantation window. The detected features of the superficial endometrial ultrastructure may be an additional indicator of the adequacy of endometrial secretory maturation. The essential histological, immunohistochemical, and ultrastructural features of the endometrium in infertility give valuable information that complements the traditional clinical classifications. Evaluation of the endometrial morphofunctional state opens up fresh opportunities to ensure an individual approach when using the regimens of assisted reproductive technologies.