Aim: to evaluate the expression of estrogen (ER) and progesterone (PR) receptors in the endometrium during the "implantation window" in women with a history of reproductive dysfunction with different endometrial thickness.Materials and Methods. A prospective single-center cohort comparative study was conducted. The main group included patients with hypoplastic (< 7 mm according to ultrasound data on preovulatory days) endometrium (n = 52), the comparison group consisted of women with normal endometrial thickness (n = 62) (women of both groups with reproductive dysfunctions of unclear cause), the control group included 16 healthy fertile women. An aspiration biopsy of the endometrium was performed on day 6–8 after ovulation with simultaneous collection of peripheral blood sample to measure level of estradiol (P). Endometrial biopsies were examined with histological and immunohistochemical (expression of ER, PR) methods.Results. All women had an ovulatory cycle, serum progesterone level ≥ 16.1 nmol/L (6–8 days after ovulation) and normoestrogenemia. E2/P was similar in all cohorts (p > 0.05). Indicators of endometrial expression of ER, PR, similar to healthy women (n = 16), were found in 21 % (n = 11 out of 52) and 32 % (n = 20 out of 62) in women from main and comparison groups, respectively. The remaining 79 % (n = 41 out of 52) of women with "thin" endometrium (main group) and 68 % (n = 42 out of 62) of patients with normal endometrial thickness (comparison group) had ER and PR expression indices in the endometrial glands and stroma with significant differences (p < 0.05) in all parameters (excepting PR in the endometrial stroma) from those of healthy women (control group), but without relevant differences between these cohorts (p > 0.05) regardless of endometrial thickness.Conclusion. In women with a history of reproductive disorders, parameters of ER and PR expression similar to those in women without reproductive problems, were noted with a "thin" (< 7 mm) endometrium by 50 % less often than those with normal thickness of the uterine mucosa. At the same time, the "thin" endometrium is not an absolute predictor of disorders of the hormone-receptor characteristics of the endometrium: in every fifth case, magnitude of endometrial expression ER, PR similar to healthy women were determined.

Aim. To evaluate the expression of steroid receptors (estrogen [ER] and progesterone [PR]) in the endometrium during the implantation window in females with a history of fertility disorders in "thin" and "absolutely thin" endometrium versus healthy females. Materials and methods. A prospective comparative study was conducted. The study group (n=42) included patients with "thin" endometrium (7 mm M-echo 5 mm at cycle days 1113 according to ultrasound); the comparison group (n=10) included females with "absolutely thin" (5 mm according to ultrasound in the pre-ovulatory days) endometrium (females in both groups had a history of infertility and miscarriage of unclear reasons in the anamnesis); the control group included 16 healthy fertile females. A Pipelle biopsy of the uterine mucosa was performed on day 68 after ovulation, and a peripheral blood sample was obtained to measure the concentration of sex steroids (estradiol [E2] and progesterone [P]). Endometrial samples were examined by histological and immunohistochemical methods (ER, PR expression). Results. All study participants had an ovulatory cycle of P16.1 nmol/L (day 68 after ovulation) and normal estrogen levels (E2, pmol/L). E2/P was similar in all cohorts (p0.05 for all measures). ER and PR expression in the endometrium similar to those in healthy females was detected in 20% of patients in the study and comparison groups (M-echo = 4.83.1 mm): 21% (9/42) and 20% (2/10), respectively. ER and PR expression in the endometrial glands and ER expression in the endometrial stroma were significantly different (p0.05) from healthy females in 79% (41/52) of patients with "thin" endometrium and 80% (8/10) of patients with "absolutely thin" endometrium. No differences in the ER or PR expression in the endometrium in females with hypoplastic endometrium were found (p0.05). Conclusion. The M-echo value does not accurately determine endometrial hormonal-receptor abnormalities: 20% of the study participants with hypoplastic endometrium had ER and PR expression comparable to those in healthy females. No differences were found in the expression of endometrial estrogen and progesterone receptors in females with "thin" and "absolutely thin" endometrium.

Aim. To assess the expression of estrogen (ER) and progesterone receptors (PR) in the endometrium during the implantation "window" in women with impaired reproductive function with low (16.1P30 nmol/l) and high (P30 nmol/l)) functional activity of the corpus luteum of the ovary. Materials and methods. A prospective single-center cohort comparative study. The main group included patients with infertility (n=93) and miscarriage (n=47) of unclear reason in the anamnesis, the control group 16 healthy fertile women. In all cases, vacuum-aspiration endometrial biopsy was performed on the 68 days after ovulation with simultaneous collection of a peripheral blood sample to determine the levels of estradiol and progesterone. Endometrial samples were studied by histological and immunohistochemical (ER, PR expression) methods. Results. Women of the main (1) and control (2) groups had an ovulatory menstrual cycle. The serum estradiol (E2) level was 691.326.5 pmol/l (1) and 707.466.1 pmol/l (2); progesterone (P) 46.11.8 nmol/l (2) and 39.14.9 nmol/l (2). Mid-secretory endometrium (results of histological examination) was determined in all healthy women (n=16) and in 46% (n=64) of the patients of the main group. All women in the control group had adequate hormone-receptor characteristics of the endometrium, in women in the main group in 45% (n=63). Comparative analysis of the expression of ER, PR in the endometrium in patients with different functional activity of the corpus luteum of the ovary was carried out in the groups 1 and 2, in women with different reproductive dysfunctions in the anamnesis (without significant differences; p0.05); subgroup analysis was performed in cohorts of women with normal (63 women in group 1 and 16 in group 2) and inadequate (77 patients in group 1) hormone-receptor status of the endometrium. There were no significant differences in the expression of ER, PR in the endometrium with low/high functional activity of the corpus luteum of the ovary with similar morphological characteristics of the endometrium (p0.05). Correlation analysis did not reveal significant relationships between the level of P in the blood and indicators of endometrial expression ER, PR (p0.05). Conclusion. In the studied cohorts, the prognostic significance of the functional activity of the corpus luteum of the ovary for the adequate expression of estrogen and progesterone receptors has not been established. To clarify the presence/absence of endometrial dysfunction in women with a history of reproductive failures, a morphological examination of the endometrium of the middle secretion phase should be carried out.

Overcoming infertility and reducing miscarriage are important challenges in obstetrics and gynecology. In the Russian Federation, the frequency of infertile couples reaches 24%; the percentage of miscarriage does not decrease, accounting for up to 20% of all desired pregnancies. The endometrial factor plays an important role in the causes of gravidar losses. Inadequate phase transformation of the endometrium is a predictor of fetal egg implantation failures. An integral part of endometrial cyclic transformations is the full proliferation of the mucous membrane of the uterine body. However, there is a cohort of women who, due to the insufficiency of proliferative processes in the endometrium, have a syndrome of thin endometrium. The pathogenesis of the formation of a hypoplastic endometrium in women with normal characteristics of hormonal factors is still poorly understood. Particular attention is paid to determining the function of proteomic markers (leukemia inhibiting factor, Forkhead box-protein family, etc.) in the genesis of the hypoplastic endometrium. This review presents an analysis of modern Russian and foreign sources on the receptivity of the endometrium, including the syndrome of thin endometrium in women of reproductive age.