Molecular and cellular events during blastocyst implantation in the receptive uterus: clues from mouse models

Abstract

The success of implantation is an interactive process between the blastocyst and the uterus. Synchronized development of embryos with uterine differentiation to a receptive state is necessary to complete pregnancy. The period of uterine receptivity for implantation is limited and referred to as the “implantation window”, which is regulated by ovarian steroid hormones. Implantation process is complicated due to the many signaling molecules in the hierarchical mechanisms with the embryo-uterine dialogue. The mouse is widely used in animal research, and is uniquely suited for reproductive studies, i.e., having a large litter size and brief estrous cycles. This review first describes why the mouse is the preferred model for implantation studies, focusing on uterine morphology and physiological traits, and then highlights the knowledge on uterine receptivity and the hormonal regulation of blastocyst implantation in mice. Our recent study revealed that selective proteolysis in the activated blastocyst is associated with the completion of blastocyst implantation after embryo transfer. Furthermore, in the context of blastocyst implantation in the mouse, this review discusses the window of uterine receptivity, hormonal regulation, uterine vascular permeability and angiogenesis, the delayed-implantation mouse model, morphogens, adhesion molecules, crosslinker proteins, extracellular matrix, and matricellular proteins. A better understanding of uterine and blastocyst biology during the peri-implantation period should facilitate further development of reproductive technology.

Adhesion molecules in gamete transport, fertilization, early embryonic development, and implantation—role in establishing a pregnancy in cattle: A review

“…This needs to be addressed given the fundamental roles for adhesion molecules presented in this review. A strong case can be made that a renewed emphasis on adhesion molecules and reproduction, combined with enabling technology platforms (e.g., assisted reproductive technology, genomics), will provide new insight into reproductive mechanisms (Matsumoto, 2017). In turn, this will inform new strategies to improve the efficiency of natural mating and assisted breeding in mammals.…”

Can trophectoderm RNA analysis predict human blastocyst competency?

“…Estradiol treatment significantly increases the proliferation of TE cells (Wilmoth et al 2010). Apart from promoting the embryo-maternal recognition, conceptus-derived estrogens alter the expression of endometrial genes related to immunity, production and transport of prostaglandin and growth factors (Ham et al 1975;Ka et al 2018), with both estrogens and progesterone altering the expression of growth factors and cytokines facilitating uterine receptivity (Dickmann et al 1975;Shemesh et al 1979;Niakan et al 2012;Matsumoto 2017). During this pre-implantation period, molecular communication between TE and endometrial cells, includes the up-regulation of cytokines by the former and certain adhesion molecules, such as CD44, by the latter (Haouzi et al 2011).…”

Comparative anatomy of the uterine tube of human and laboratory white rat females

“…The role of cilia is most pronounced in the ampulla of the uterine tube, where the thickness of the subserosa is up to five times smaller than the isthmus [6,13]. According to many authors, the contraction of the subserosa help to captures the egg by fimbriae [2,4,19]. Other authors believe that the frequency of cilia movement influences the speed of movement of the egg and the embryo [8,16,22].…”