Blastocyst implantation

Provided these two processes are in phase, the conditions are then optimal for fertilisation, proliferation of the zygote to form the blastocyst, implantation of the latter and maintenance of pregnancy. Before ovulation, the development of the ovum and hormone secretion take place in a single structure, the follicle. 

The blastocyst implants into the maternal endometrial wall on about the 7th day of embryonic life. Trophoblastic cells attach to the uterine mucosa by apposition and adhesion. Under the influence of progesterone and estrogen, the uterine lumen closes, which brings the blastocyst into close contact with the endometrium. Adhesion of the trophoblastto the uterine epithelium occurs with increasing apposition and involves cell surface glycoproteins. The uterine epithelium is penetrated by syncytial growths on the trophoblast into the adjacent uterine epithelial cells. Subsequently, the trophoblastic membranes... 

In low concentrations prepares uterus for blastocyst implantation promotes ovulation and mammary gland development regulates female sex accessory organs weak, corticosteroid properties precursor to sex hormones... 

S. J. (1992). Blastocyst implantation depends on maternal expression of leukemia inhibitory factor. Nature 359, 76-79. 

Kennedy TG (1977) Evidence for a role for prosaglandins in the initiation of blastocyst implantation in the rat. Biol Reprod 16 286-291... 

Recent studies show that LPA3 has a crucial role in blastocyst implantation through COX-2, which generates prostaglandins (PGs) E2 and I2 (Hama et al., 2006, 2007 Shah and Catt, 2005 Ye et al., 2005). SIP can also act to prevent intrinsic, chemical, and irradiation-induced oocyte apoptosis. SIP pretreatment improves the rate of successful pregnancy in irradiated mice (Morita et al., 2000 Tilly, 2001). Thus, controlling LP signaling could be a valuable therapeutic option in human infertility. 

CDF/LIF, identified only relatively recently, has become one of the most extensively studied cytokines and turned out to play a remarkable varietyof roles in living organisms. Recent advances in molecular and cellular biological studies of CDF/LIF reveal that this factor has at least three important specific functions in vivo. First, it is essential for blastocyst implantation. Second, it is required for self-renewal of a group of myeloid stem cells. Third, it probably functions as a repair factor following nerve injury and in some host defence systems. It remains, however, unknown in what manner CDF/LIF, as a member of the EL-6 family, interacts with other cytokines and growth factors to fulfil these and other complex physiological functions. 

Bhatt, H., Brunet, L.J. and Stewart, C.L. (1991) Uterine expression of leukemia inhibitory factor coincides with the onset of blastocyst implantation, Proc. Natl. Acad. Sci. USA 88 11408-11412. 

In the luteal (or secretory) phase of the cycle, elevated progesterone limits the proliferative effect of estrogens on the endometrium by stimulating differentiation. Progesterone is thus important in preparation for implantation and for the decidual reaction that takes place in the uterus at the implantation site. There is a narrow window of implantation, spanning days 19—24 of the cycle, when the epithelial cells of the endometrium are receptive to blastocyst implantation. 

Paria BC, Elenius K, Klagsbrun M, Dey SK. Heparin-binding EGF-like growth factor interacts with mouse blastocysts independently of ErbBl a possible role for heparan sulfate proteoglycans and ErbB4 in blastocyst implantation. Development 1999 126 1997-2005. 

The last three compounds which have been included in the group of synthetic estrogen analogs can be considered as ring-closed variants of the triaryl-ethylenes. The tetrahydronaphthyl derivative (LV) has been found to be less active than the following two compounds [169]. Nafoxidine (LVI) [170] and Su-13,320 (LVII) [171] possessed hypocholesterolemic activities in the rat at doses lower than 1 mg/kg. Both compounds were reported to be potent inhibitors of blastocyst implantation in the rat at 25 (xg/kg [172]. The hypocholesterolemic and antifertility properties of these substances may be due to their inherent estrogenic potency at low doses. The c s-isomer of Su-13,320 was found to be... 

The actual evidence Is that blastocyst implantation is only possible if some oestrogen has been produced under the influence of the pituitary graft. Electron microscopic studies of pituitary grafts under the kidney capsule show that FSH and LH cells are still present in this tissue (Rennels, Potvliege). The overwhelming dominant type of cells is however the typical prolactin cell. 

RNA-Induced Blastocyst Implantation in Postcoitally Ovariectomizbd Rats... 

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