What happens when the embryo implants in the uterus?

Embryo implantation is a relatively new concept that many people are not yet familiar with. Embryo implantation is a process in which sperm and egg are combined in vitro to form a blastocyst, which is then implanted into the uterus. The blastocyst develops and then promotes the formation of the placenta. This is a new way of achieving pregnancy, and it has only been successfully tested on mice. This article introduces the details of placenta implantation. Let’s take a look and learn about it.

What is embryo implantation?

Embryo implantation refers to a series of cellular or molecular biological events from egg fertilization to blastocyst implantation, which is regulated by a complex network system composed of numerous active molecules at various levels. It mainly includes free blastocyst, adhesion and penetration, and placenta formation, and this process is precisely regulated by many factors. Recent studies have shown that cytokines mediate ovarian steroid hormones to regulate the proliferation and differentiation of endometrial or embryonic cells, affecting the maternal and fetal physiological states and the local microenvironment of embryo implantation, and all perform important physiological functions during the embryo implantation period.

2. Factors affecting embryo implantation

1. Embryo invasiveness

In hemochorionic placental animals, successful implantation requires the blastocyst to have the ability to bind to, penetrate the uterine epithelium, and implant into the endometrium. The mature blastocyst has two different characteristics. One is the ability to bind cells to cells and cells to the matrix, which is called adhesion. The other is the ability to insert between epithelial cells, separate these cells, and degrade the extracellular matrix (ECM) components, which is called permeability.

2. Endometrial receptivity

Endometrial cells have the unique property of being able to assume different physiological states: neutral, receptive, non-receptive or inhibitory. The endometrium can only accept embryo implantation during the receptive period, also known as the implantation window, and is inhibitory to implantation outside of the receptive period. Endometrial receptivity was first demonstrated in rats and is primarily regulated by ovarian steroid hormones.