Placenta- Shaw Flashcards
What 2 cells types make up the trophoblast?
Cytotrophoblast
Syncytiotrophoblast
Cytotrophoblast
Inner Layer of chorionic villi
Proliferate
When do trophoblast cells become cytotrophoblast cells?
After attachment to the endometrium!
In what phase of the uterine cycle does implantation occur?
During the secretory phase
Describe Syncytiotrophoblast cells
Outer layer of chorionic villi
Don’t have boundaries
Multinucleated
Secrete hCG
**Lack MHCI expression to decrease chance of attack by maternal immune system
Primary Villi
Trophoblast only (syncytiotrophoblast outside and cytotrophoblast inside)
**No extraembryonic mesoderm or blood vessels yet
Secondary Villi
Mesodermal ingrowth into core of primary villus
Branching occurs
Tertiary Villi
Differentiation of blood vessels in the mesodermal core of secondary villus
*Anastomosis of villar blood vessels with fetal circulation
Describe an anchoring villus
Tertiary Villi
Cytotrophoblast has grown outside of syncytiotrophoblast to form a cytotrophoblastic shell
**Cytotrophoblast makes direct contact with decidual cells in endometrial stroma
What is the decidual reaction?
Transformation of endometrial stromal cells
- Swell due to glycogen and lipid accumulation
- Transformation spreads through out superficial layers of endometrium
What are the 3 placental components?
Decidua basalis
Decidua capsularis
Decidua parietalis
What constitutes the maternal portion of the placenta?
Decidua basalis
*site of decidual reaction and most extensive villar invastion
Decidua capsularis
Layer of placent between conceptus and uterine lumen
*becomes attenuated ast the embryo grows and eventually regresses
Decidua parietalis
Remainder of endometrium not occupied by decidua basalis
Cotyledons
Adjacent to decidua basalis
Placenta divided into 15-30 lobules by septae from decidua basalis
How many tertiary villi are within a cotyledon?
2-4 and their branches
What happens to the placental barrier as pregnancy progresses?
Gets thinner!
What forms the cotyledons of the placenta?
Decidua Basalis
TORCH Infections
Toxoplasmosis other infections (Parvo B19) Rubella CMV Herpes/HIV e Syphillis
What placenta cells secrete hCG?
Syncytiotrophoblasts
*helps maintain corpus luteum and its production of progesterone and estrogen
What do the synctiotrophoblasts secrete? 4 things…
- hCG
- Progesterone (at 12 wks)
- Human placental lactogen
- Converts androgens produced by fetal adrenal glands to estrogen
What 3 things are produced by the decidua basalis?
Prolactin
Prostaglandins
Relaxin
Relaxin is secreted by the decidua basalis… what does it do?
Softens pubic symphysis prior to parturition
