Embryo implantation involves a complex interaction between the embryo and the endometrium of the mother, the study of which faces a variety of problems. The modeling of endometrial epithelial organoids and endometrial assembloids provides a new way to study the process of embryo implantation in vitro. This paper summarized the latest research progress in embryo implantation, the regulation mechanism of endometrial receptivity by estrogen- progesterone coordination and embryo-derived signals, the establishment of endometrial organoids, and the development and application of endometrial assembloids in the research on mother-embryo interaction, providing new strategies for studying the communication between embryo and maternal uterus during implantation.
Endometrium/physiology* ; Organoids/cytology* ; Embryo Implantation/physiology* ; Female ; Animals ; Progesterone/pharmacology* ; Pregnancy ; Estrogens/metabolism* ; Humans

OBJECTIVETo investigate the role of endometrial macrophages in embryo implantation and in regulating the expression of vascular endothelial growth factor A (VEGFA) in mouse endometrium during the peri-implantation period.

METHODAt D3.5 (D0.5 defined as the morning when a vaginal plug was observed), pregnant mice were divided randomly into experimental group, control group and blank group. In the experimental group, the mice were subjected to intrauterine injection of clodronate liposomes on the left side of uterus to eliminate the macrophages, and PBS liposomes on the right side. PBS liposomes and PBS were administered in the control and blank groups, respectively. The uterine tissues were collected on D5.5 and stained with trypan blue to show the implantation sites. Flow cytometry was performed to examine the percentage of F4/80(+) CD11b(+) macrophages macrophages in the uterus. F4/80(+) macrophage population within the endometrium and ovary and changes in VEGFA expression at the implantation and non-implantation sites were examined using immunohistochemistry.

RESULTSEndometrial F4/80(+) CD11b(+) macrophages macrophages were significantly reduced by 74% following intrauterine injection of clodronate liposomes (P<0.05). The number of macrophages in the ovaries showed no significant difference among the 3 groups. In the experimental group, the left side of the uterine showed imcomplete cavity closure with a lower number of implantation site than the right side (2.20∓1.81 vs 5.10∓1.91, P<0.05). VEGFA expression at the implantation site were significantly decreased in the endometrium on the left side with macrophage suppression as compared with that on the right side (P<0.05).

CONCLUSIONEndometrial macrophages appear to modulate uterine receptivity by regulating the expression of VEGFA to affect embryo implantation, suggesting the important role of macrophages in embryo implantation.

Animals ; Embryo Implantation ; Endometrium ; physiology ; Female ; Immunohistochemistry ; Macrophages ; cytology ; Mice ; Ovary ; cytology ; Pregnancy ; Random Allocation ; Uterus ; cytology ; Vascular Endothelial Growth Factor A ; physiology

BACKGROUNDEndometriosis (EM) is a benign gynecologic disease predominantly found in women of reproductive age. However, its pathogenesis is still poorly understood. Our experiment was designed to establish a stable and reliable cultural environment for coculture of endometrium and peritoneum, so as to observe the adhesion/invasion ability of endometrium from patients with or without EM.

METHODSEndometria of secretory phase and peritoneum were sampled from 6 women with endometriois during laparoscopy. Six with ovarian teratoma or simple ovarian cyst were taken as control. We cocultured endometrium and peritoneum into four groups (endometrium from EM cultured with peritoneum from EM, endometrium from control cultured with peritoneum from control, endometrium from EM cultured with peritoneum from non-EM and the endometrium from control cultured with peritoneum from EM) to observe the adhesion/invasion process in gas-liquid surface culture and in-medium culture. Specimens were collected at 1 hour, 6 hours, 12 hours, 24 hours, 2 days, 3 days, 4 days, 5 days, 6 days and 7 days for histology, immunofluorescence and immunohistochemical analysis on cytokeratin 8 (CK8) and CD10.

RESULTSThe gas-liquid surface culture was superior to in-medium culture for the maintenance of tissue morphology and survival of endometrium. CK8 immunoflurescence demonstrated no remarkable difference in adhesion process between patients with and without EM. CD10 immunochemistry manifested frequent invasion of endometrial stromal cells from EM patients into peritoneum of up to 3 days culture, while the endometriotic cells from non-EM patients did not invade into peritoneum.

CONCLUSIONSGas-liquid surface culture is a suitable model for observing the early events in EM lesion formation. Endometrium from patients with EM showed increased invasion capacity during coculture, which might help to explain the etiology of endometriosis.

Cell Adhesion ; physiology ; Endometriosis ; pathology ; Endometrium ; cytology ; Female ; Humans ; Tissue Culture Techniques ; methods

OBJECTIVETo explore the potential mechanism of breakthrough bleeding associated with progestin with in vitro methods.

METHODSThe isolation and culture of human endometrial endothelial cells (HEECs) was performed with the method established in our laboratory. The content and activity of urokinase-type plasminogen activator (uPA) and the content of plasminogen activator inhibitor-1 (PAI-1) in cell supernatants after incubated with different concentrations of progesterone (0-5 micromol/L) and 17beta-estradiol (0, 0.1, or 1 nmol/L) were measured by method of ELISA. Apoptosis rate of HEECs was measured by flow cytometry. Viable cell count was measured by MTT.

RESULTSThe increased level of progesterone (0.5-5 micromol/L) combined with 17beta-estradiol elevated content and activity of uPA while the production of PAI-1 remained unchanged. The apoptosis of HEECs was inhibited along with the increment of total viable cell counts at higher concentrations of progesterone with 17beta-estradiol.

CONCLUSIONThe inhibition of apoptosis and increased content and activity of uPA may contribute to the occurrence of irregular bleeding associated with progestin use to some extent

Apoptosis ; drug effects ; physiology ; Endometrium ; cytology ; physiology ; Endothelium ; cytology ; physiology ; Estradiol ; pharmacology ; Female ; Humans ; Metrorrhagia ; etiology ; Progestins ; physiology

Eighty eight cases of the endometrial biopsy comprising 19 cases of proliferative phase, 21 cases of secretory phase, and 23 cases of menstrual phase from non-sterility patients, and 25 cases of the endometrium at the first day of menstruation from primary sterility patients were examined histochemically. Secretory substance in the epithelial cells of the endometrial glands during the secretory phase and menstrual phase was main1y glycogen. Therefore, it is essential to fix the endometrial tissue in a fixative which can preserve glycogen for the detection of secretory activity more accurately. Among 25 cases of primary sterility, 15 cases showed epithelial secretory vacuoles on hematoxylin and eosin stained sections, and no epithelial vacuolization was noted in the remaining 10 cases. However, PAS staining showed presence of PAS positive diastase sensitive substance in the majority of the later 10 cases except one in which no PAS positive substance was found, indicating that PAS staining is superior than routine hematoxylin and eosin staining for the detection of epithelial secretory substance. The absolute lack of secretory activity in the endometrial glands was infrequent, but a relative decrease of progesterone effect was rather common among the patients complaining primary sterility, and the decreased progesterone effect may not necessarily be due to the absence of ovulation.
Adult ; Endometrium/*cytology/*physiology ; Female ; Histocytochemistry ; Human ; Infertility, Female/pathology ; Ovulation/*physiology ; Progesterone/analysis ; Secretory Rate