Morphological features of endometrial pinopodia formation during the luteal phase in women with previous unsuccessful implantation

Abstract

Pinopodia of the receptive endometrium is one of the prerequisites for successful embryo implantation. Study objective: to analyze the morphological changes of the endometrium in infertile women, in particular to investigate the apical surface of epithelial cells and pinopodia formation. Materials and methods. 12 patients with a history of previous implantation failure were examined. Patients underwent hysteroscopy with biopsy under intravenous anesthesia on 20–24th day of the menstrual cycle. Morphological structure of pinopodia on the surface of the endometrial epithelium was evaluated by scanning electron microscopy. Results. Apical surface of epitheliocytes was damaged in 16.7% studied biopsies. Morphological picture and maturity of the endometrial glands did not correspond to the actual day of the menstrual cycle in 41.7% biopsies. Degree of glands maturity in these patients was low, so there was a delay in the menstrual cycle. Ultrastructural examination showed clear changes in the structure of secretory and ciliary cells in 33.3%. On the apical surface of the secretory cells there was no or small number of microvilli; cilia of eyelashes were shortened or sometimes fused together. Pinopodia as a one of the most important components of implantation was detected in only 50% of patients. Only in 33.3% of participants visualized fully developed, mature pinopodia. Conclusions. Analysis of own data showed that in the endometrium of women with previous unsuccessful implantation there are certain morphological changes, which are physiologically manifested by a delay in the luteinizing phase of the menstrual cycle and, possibly, as a result mismatch of endometrial structure and embryo maturity. Time of pinopodia onset in participants varied from 20 to 24 days of the menstrual cycle. It is necessary to improve the design and conduct further research to study the association between the expression of receptivity markers and ultrastructural structure.

Keywords

• infertility
• pinopodia
• endometrium
• ciliated cells
• secretory cells