Intrauterine Signaling and Embryonic Implantation

Abstract

In mammals, the uterus is modified to be able to contain a pregnancy and nurture the developing embryo. In deciduate mammals, this is apparently due to formation of a special compartment, lined with decidual tissue, in which a semi-allogeneic (or even allogeneic, after embryo transplantation) pregnancy is accommodated. This review treats the mechanisms which have been evoked to explain the implantation of the egg and the decidualization of the implanting endometrium. At least three different neurochemicals have been considered to mediate induction of this response: histamine, prostaglandins and platelet-aggregating factor. Their importance is reviewed. The ability of the endometrium to transform into decidual tissue is contingent on the presence of the epithelium. The role of the epithelium is temporary, however, since it dies and is sloughed within a day of the induction. Studies of progesterone-dependent changes in the epithelial reaction to preimplantation pregnancy are considered.

The Immune System and the Role of Inflammation in Perinatal Depression

“…The identification of TLRs in several pathologies have led to a better understanding of the mechanisms by which the innate immune system recognizes non-self-molecules and how TLRs promote the detection of invading pathogens [154]. TLRs recognize endogenous DAMPs, including HSPs and high-mobility group box 1 (HMGB1), in addition to exogenous pathogen-associated molecular patterns, such as LPS and MAMPs [109,110].…”

“…The TLR2 subfamily consists of TLR1, TLR2, TLR6, and TLR10, while the TLR9 subfamily is composed of TLR7, TLR8, and TLR9. TLR3, TLR4, and TLR5 each represent a family with only one member [154]. TLR4 recognizes the LPS motif in the cell membrane of all gram-negative bacteria, while TLR2 recognizes lipoteichoic acid expressed in gram-positive bacteria [114].…”

“…Most of the TLRs expressed in cells are pre-assembled into heterodimeric complexes on the cell surface or in the cytosol, in order to activate the cell-signaling pathway and transcription factors regulating the expression of genes responsible for promoting host-defense mechanisms, such as, the mammalian antimicrobial peptide (defensins), the antiviral response (type I interferons), pro-inflammatory cytokine secretion, co-stimulation of membrane-bound antigens, and dendritic cell maturation after activation of inflammatory responses (for extensive review, see [154,155]).…”

“…Thus, the innate immune system senses invading microorganisms by a phylogenetically-conserved family of pattern-recognition receptors of which TLRs are the most important; although this system provides a less specific response, it is nevertheless critical for the prevention of microbial invasion. Activation of TLRs results in the induction of innate immunity mechanisms, including the development of antigen-specific adaptive immune responses bridging innate and adaptive immunity in mammalian and other vertebrate species [154].…”

Proteomic Profiles of the Embryonic Chorioamnion and Uterine Caruncles in Buffaloes (Bubalus bubalis) with Normal and Retarded Embryonic Development1

“…Retarded chorioamnions showed up-regulation of amine oxidase-A, which can catalyze the oxidation of a wide range of neurotransmitters and also serve as a potent vasoactive mediator to regulate blood flow and capillary permeability [68]. Amine oxidase-A is up-regulated in the uterus of mice during the peri-implantation period, which could indicate a role in implantation of blastocysts and endometrial receptivity [69].…”