Implantation

It is the process by which blastocyst is embedded in the endometrium.

Timing: Starts at 6th day and completed at 11th day.

Site: usually at upper part of posterior wall of uterus near fundus.

Dr. Sherif Fahmy

Blastocyst Formation

Dr. Sherif Fahmy

Steps of Implantation Blastocyst fixes its embryonic pole to site

of implantation. Syncytiotropholast erodes endometrium

till blastocyst reach spongy layer of endometrium.

Endometrium of pregnancy is called decidua.

Site of penetration is closed by fibrin clot at 9th day.

Surface epithelium overgrows the fibrin clot at 11th day Dr. Sherif Fahmy

Dr. Sherif Fahmy

Dr. Sherif Fahmy

Dr. Sherif Fahmy

Dr. Sherif Fahmy

Abnormal Sites of Implantation

1- Ectopic pregnany: They are tubal, ovarian or abdominal.

2- Placenta praevia: lateralis, marginalis and centralis.

Dr. Sherif Fahmy

Placenta Praevia

Dr. Sherif Fahmy

Dr. Sherif Fahmy

Decidua

It is endometrium after implantation. Character of endometrium:

Increased secretory function of uterine glands.

Decidual cells are stromal cells filled with glycogen.

Arteries become more spiral with arterio-venous anastomosis.

Dr. Sherif Fahmy

Dr. Sherif Fahmy

Dr. Sherif Fahmy

Parts of decidua:

Decidua basalis: It is the part of decidua between blastocyst and myometrium.

Decidua capsularis: It covers the blastocyst and separates it from uterine cavity.

Decidua parietalis: It is the rest of endometrium.

Dr. Sherif Fahmy

Fate of decidua:

Decidua basalis shares in the formation of placenta.

Decidua capsularis and parietalis fuse together and sheded with placenta after delivary.

Dr. Sherif Fahmy