| Objective①To observe the histological changes of the endometrium of unpregnant (estrous stage), pregnant and pseudopregnant mice in the peri-implantation;②To observe the ultrastructure changes in the endometrium of unpregnant (strous stage) and pregnant mice in the peri-implantation;③To analyze the expressions and distributions of IGFBP-4 and IGF-2 in the endometrium of unpregnant (estrous stage), pregnant and pseudopregnant mice in the peri-implantation;④To explore the association between the expressions of IGFBP-4 and IGF-2 in the endometrium of pregnant mice in the peri-implantation. Methods Three Kunming adult female mice were caged with a normal or a vasoligation male overnight. In the following morning, females were checked for the presence of a vaginal sperm plug. The day of vaginal plug was regarded as day 1 of pregnancy or pseudopregnancy. Firstly, 120 pregnant mice and 120 pseudopregnant mice of day 1-8 were put to death through cervical vertebrae luxation, and then the uteri were disemboweled and the unpregnant mice uteri were (estrous stage) taken as controls.The uteri were fixed in 4% paraformaldehyde. The fixed uteri were stained by Hematoxylin-Eosin-(HE) and the histological structures was observe; Ultrastructure changes in the endometrium of pregnant and pseudopregnancy mice of day 3-6 were detected by transmission electron microscope(TEM); Immunohistochemical SP staining was used to measure the expression of IGFBP-4 and IGF-2. The pictures of histological structures and ultrastructure were taken by microscopic imaging system and then were analysed by computer.On day 4 of 120 pseudopregnant mice, the double uteri horn of abdominal surgical were extracted and vegetable oil of 0.1mL was injected into one uterine horn to stimulate a decidual reaction, and the contralateral uninjected uterine horn was served as a control.In the pseudopregnant of 8 day the mice were killed through cervical vertebrae, and then the uterus dealed with vegetable oil were disemboweled. The uteri were fixed in 4% paraformaldehyde, and stained by Hematoxylin-Eosin (HE) was used to measure. The expression of IGFBP-4 and IGF-2 was examinated by immunohistochemical SP stainin. The photoes about the expression were taken by microscopic imaging system and then the results of immunohistochemical staining were analysed by computer. Results①The HE staining results showed that the structural changes of mice endometrium exhibited the developmental tendency on day 1-8 of pregnant. The amounts of uterine glands increased gradually, and glandular become irregular, the secretions of a small amount, and blood vessels proliferation, and the endometrium showed physiological edema. Moreover, the intercellular space of stroma cells became augmented, pre-implantation (on day 1-3 of pregnancy ).The amounts of uterine glands a further increased gradually,and glandular become very irregular,and full of secretions, and blood vessels further proliferation, curved and spiral distribution,and stromal cells become very hypertrophy ,and uterus intimal a further of thickening, implantation (on day 4-5of pregnancy); After of completion of embryo implantation, with the above two features, the proliferation of stromal cells completely differentiated into decidual cells, post-implanted (on day 6-8 of pregnancy).②Under TEM, cell organs in glandular epithelium, luminal epithelium and on day 3-6 of pregnancy were more than those in unpregnant mice(estrous stage). Especially in the implantation (on day 4-5 of pregnancy), Abundant Mi, GC, RER, RG, SG and so on in glandular epithelium, luminal epithelium and stroma cells in endometrium and interstitial edema were observed, respectively. Moreover, stroma cells got hypertrophy, abound with affluent glycogen; lipid droplet intracytoplasm and lysosome. The changes of mouse endometrium is not very clear on day 3-6 of pseudopregnancy, and on day 3-4 of pseudopregnancy the similar changes of endometrium ultrastructural appeared on day 3-4 of pregnant. The cell organs in glandular epithelium, luminal epithelium and stromal cells were more than those in unpregnant mice(estrous stage), while on day 5-6 of pseudopregnant endometrium displayed no changes almost difference with in unpregnant mice.③The immunohistochemical staining results showed that on day 1-8 of pregnant, IGFBP-4 was expressed in endometrium mouse on day 3 of pregnant, and the positive products were mainly distributed in the endometrial glandular epithelium, luminal epithelium and the stromal cells, The expression of the IGFBP-4 reached the peak on day 5-6 of pregnant mice;on day 7-8 of decreased; on day 1-8 of pseudopregnant, IGFBP-4 was expressed in endometrium mouse on day 5 of pseudopregnant, which was mainly distributed in the endometrial glandular epithelium and luminal epithelium, and whose expression level is similar to unpregnant mice(estrous stage); but not expressed in stromal cells; on day1-8 of pregnant; IGF-2 was mainly expressed in endometrial glandular epithelium, luminal epithelium and stromal cells. The expression of the IGF-2 reached the peak on day 5-8 of pregnant mice; on day 1-8 of pseudopregnant, IGF-2 was detected in the glandular epithelium, luminal epithelium and stromal cells on day 3 of pseudopregnant. The expression level of IGF-2 is similar to that in unpregnant mice (estrous stage); otherwise IGFBP-4 and IGF-2 expression of both decidua endometrium of pregnant and pseudopregnant mice were mainly distributed in the whole decidual cells, glandular epithelium. Conclusions①The morphological changes in the endometrium of pregnant mice exhibted a dynamic changing tendecy and the prominent changes appeared during the window of implantation;②The continued expression of IGFBP-4 in the endometrial of pregnant mice on day 3-8 suggested that IGFBP-4 might play an important role in the process of the embryo implantation in mouse;③The continued expression of IGF-2 in the endometrial of pregnant mice on day 1-8 suggested that IGF-2 might play an important role in the process of the embryo implantation in mouse;④In the endometrium of pseudopregnant mice, the laws revealed that the expressions of IGFBP-4 and IGF-2 were regulated not only by matemal hormone, but also by the implanted embryos and endometrial stimulation and secretion;⑤The expression and distribution of IGFBP-4 and IGF-2 in the mice of endometrial decidual cells in pregnant and artificial decidualization, suggested that both may be involved in embryo implantation in mice and plants into the endometrial decidualization.
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