Question

Write a short note on IMPLANTATION

Answer 1

IMPLANTATION

It is a process of attachment and invasion of uterus endometrium by blastocyst in the placental animals.

The process by the end of 1st week of ovulation of successful fertilization. Implantation is the first stage in the development of placenta which is essential for fetus growth and development.

Uterus endometrium gets thick, before implantation.

For short answer

1. The embryo enters into the uterine activity as 8cell morula, before implantation it divides itself into 30 to 200 cell blastocysts before implantation

2. Endometrium prepare it self by complex activity of cytokines, growth factor, lipids modulate for hormones.

3. The process of implantation consists of 3 key steps

a. Apposition – this is a major step in the implantation followed by hatching of blastocyst from its zona pellucida, blastocyst come in contact with uterine luminal epithelium and form weak bond. Structural changes occur, microvilli of the apical surface of cytotrophoblast interlock with micro protrusion called pin pods which are present on the apical surface of endometrium.

This interlock causes changes in the body like release of progesterone, preparation of endometrium, yolk Salk development etc.

b. Attachment – followed by apposition, adherent or attachment occur, which characterized by increased physical contact with endometrium of the uterus. It Is much stronger than apposition, adhering activity occur at microvilli of triploblastic. Triploblastic consist of fiber connection, collagen and integrin which assist in adhesion activity and cell glycoprotein also help in adhesion.

c. Invasion- it is the further establishment of blastocytes in the endometrium

-blastocytes attaches to endothermal cell

-blastocytes differentiate into inner cytotrophoblast or outer syncytiotrophoblast.

-microvilli of outer part of blastocytes invades the endometrium, blastocytes get embedded into the uterus and defect at the site of invasion is repaired.

-maternal blood filled with lacunae and appear in syncytiotrophoblast this start primitive uteroplacental circulation.

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