Implantation It is the process by which blastocyst is embedded in the endometrium. It is the process by which blastocyst is embedded in the endometrium. Timing: Starts at 6 th day and completed at 11 th day. Timing: Starts at 6 th day and completed at 11 th day. Site: usually at upper part of posterior wall of uterus near fundus. 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. Blastocyst fixes its embryonic pole to site of implantation. Syncytiotropholast erodes endometrium till blastocyst reach spongy layer of endometrium. Syncytiotropholast erodes endometrium till blastocyst reach spongy layer of endometrium. Endometrium of pregnancy is called decidua. Endometrium of pregnancy is called decidua. Site of penetration is closed by fibrin clot at 9 th day. Site of penetration is closed by fibrin clot at 9 th day. Surface epithelium overgrows the fibrin clot at 11 th day Surface epithelium overgrows the fibrin clot at 11 th day Dr. Sherif Fahmy

Abnormal Sites of Implantation 1- Ectopic pregnany: They are tubal, ovarian or abdominal. 1- Ectopic pregnany: They are tubal, ovarian or abdominal. 2- Placenta praevia: lateralis, marginalis and centralis. 2- Placenta praevia: lateralis, marginalis and centralis. Dr. Sherif Fahmy

Placenta Praevia Dr. Sherif Fahmy

Decidua It is endometrium after implantation. It is endometrium after implantation. Character of endometrium: Character of endometrium: Increased secretory function of uterine glands. Increased secretory function of uterine glands. Decidual cells are stromal cells filled with glycogen. Decidual cells are stromal cells filled with glycogen. Arteries become more spiral with arterio-venous anastomosis. Arteries become more spiral with arterio-venous anastomosis. Dr. Sherif Fahmy

Parts of decidua: Decidua basalis: It is the part of decidua between blastocyst and myometrium. 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 capsularis: It covers the blastocyst and separates it from uterine cavity. Decidua parietalis: It is the rest of endometrium. Decidua parietalis: It is the rest of endometrium. Dr. Sherif Fahmy

Fate of decidua: Decidua basalis shares in the formation of placenta. Decidua basalis shares in the formation of placenta. Decidua capsularis and parietalis fuse together and sheded with placenta after delivary. Decidua capsularis and parietalis fuse together and sheded with placenta after delivary. Dr. Sherif Fahmy