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@~PLACENTA.ppt
- 1.
- 2. Functions: • Exchange ofgases • Transport of nutrients • Excretion of waste products • Transmission of maternal antibodies • Barrier function • Storage function
- 3. Fetal Membranes • Structurederived from fertilized ovum and not share in formation of embryo Fetal membrane include 1. Amnion 2. Chorion 3. Yolk sac 4. Allantois 5. Connecting stalk/ Umb. Cord 6. Placenta
- 4. • It isthe fetomaternal organ. • Placenta has dual origin – Foetal component – chorion – Maternal component – decidua basalis Layers of Uterus 1. Perimetrium/Serosa 2. Myometrium (LCL) 3.Endometrium i. Stratum basalis ii.stratum spongiosum iii.stratum compactum (decidual layer) Gravid endometrium = decidua
- 6. Interstitial type ofimplantation
- 8. Syncitiotrophoblast start secretinghCG After implantation endometrium undergoes changes k/a Decidual Reaction
- 11. • Finger likechorionic villi formed all around the chorionic sac • Formed by trophoblast and EEM • As the chorionic sac enlarges – Chorionic villi in region of D. capsularis get compressed and degenrate. This smooth chorion is k/a chorionic leavae – Chorionic villi in region of D. basalis grow extensively. This part of chorion is k/a chorionic frondosum
- 12. • Lacunae areseparated from each other by columns of syncitiotrophoblasts, k/a trabeculi
- 13. • Cells ofcytotrophoblast invade the trabiculae in center. – trabiculae has two layers – k/a Primary Villi • Outer layer - syncitiotrophoblasts • Inner core - cytotrophoblast • Somatopleuric EEM deep to cytotrophoblast invade inner core of Primary Villi – k/a Secondary Villi • Blood vessels develops in EEM – k/a Tertiary villi
- 19. Tertiary villi continuousbetween chorion and decidua these villi are also called STEM VILLI - or ANCHORING VILLI (cytotrophoblast cells attached to maternal tissue)
- 20. • branched villi- or terminal villi, grow from sides of stem villi, – region of main exchange, – surrounded by maternal blood in intervillous spaces • The anchoring villi give off numerous offshoots that grow and move freely into intervillous spaces as free villi
- 22. Lobulation of Placenta •After the formation of anchoring villi, a number of septae grow inward from the uterine endometrium into the inter-villous spaces and divide the placenta into (15–20) lobes called cotyledons. Each cotyledon contains 2–3 anchoring villi.
- 24. Features of afull-term placenta • It is like a flat circular disc (i.e., discoid). • Haemochorial placenta - where the chorion comes in direct contact with maternal blood (e.g. human) • It has a diameter of 15–20 cm. • It weighs about 500 g. • It presents two surfaces: maternal and fetal. a) Its maternal surface presents 15–20 lobes/cotyledons. b) Its fetal surface presents a smooth shining surface, at the approximate center of which the umbilical cord is attached
- 25. • Placental barrier- 4 layers separate maternal and fetal blood: (25 to 2 µ thick) 1. syncitiotrophoblast, 2. cytotrophoblast, 3. villi connective tissue • BM of cytotrophoblast • EEM 4. Fetal capillary endothelium with BM
- 26. Placental circulation • Maternalplacental circulation – About 80–100 spiral arteries & veins open into the intervillous spaces. – under pressure of blood in arteries, the blood reaches right up to the chorionic plate. • Fetal placental circulation – fetal blood comes to placenta through the umbilical arteries. – These arteries after entering the placenta ramify freely in the chorion and their branches enter the chorionic villi. – The veins from the chorionic villi drain into the umbilical vein that carries blood rich in oxygen (O2) and nutrients to the fetus from placenta.
- 28. Congenital Anomalies ofthe Placenta • Anomalies Due to Abnormal Shape • Anomalies Due to Abnormal Site of Attachment of UC Abnormal Site of Attachment of UC
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Editor's Notes
- #26 villi connective tissue – mesenchymal core