Placenta Histology

Question 1

What are the things required for Implantation and Placenta formation?

Answer 1

Endometrial invasion. Secretory phase endometrium required. Trophoblast proliferation (lacunar formation, contact with uterine venous sinuses). Uterine epithelium regeneration. Decidual reaction.

Question 2

What are the components of the chorionic villi?

Answer 2

Extra embryonic mesoderm, cytotrophoblast, syncytiotrophoblast, blood vessels

Question 3

What is a Primary villi?

Answer 3

Trophoblast only (syncytiotrophoblast (outside), cytotrophoblast (inside)). No extra embryonic mesoderm or blood vessels yet.

Question 4

What is a Secondary villi?

Answer 4

Mesodermal ingrowth into core of primary villus. Branching occurs. Three parts: Syncytiotrophoblast (outer), Cytotrophoblast, Mesodermal core (inner)

Question 5

What is a Tertiary villi?

Answer 5

Differentiation of blood vessels in the mesodermal core of a secondary villus. Anastomosis of villa blood vessels with fetal circulation.

Question 6

What are Anchoring Villi vs Free Villi?

Answer 6

All tertiary villi. Cytotrophoblastic shell formation (invasion of cytotrophoblast through syncytiotrophoblast, Cystotropoblast makes direct contact with decidual cells in endometrial stroma). Anchoring villi are connected to shell. Free villi are not connected to shell.

Question 7

What is the decidual reaction?

Answer 7

Transformation of endodermal stromal cells (swell due to glycogen and lipid accumulation, transformation spreads throughout superficial layers of endometrium). Occurs during each menstrual cycle and is enhanced after implantation.

Question 8

What are the three placental components?

Answer 8

Decidua basalis, Decidua capsularis, Decidua parietalis

Question 9

What is the Decidua basalis?

Answer 9

Between conceptus and myometrium. Constitutes maternal portion of placenta. Site of decidual reaction and most extensive villi invasion.

Question 10

What is the Decidua capsularis?

Answer 10

Between conceptus and uterine lumen. Becomes attenuated as the embryo grows and eventually regresses.

Question 11

What is the Decidua parietalis?

Answer 11

Remainder of endometrium.

Question 12

What are Cotyledons?

Answer 12

Adjacent to the decidua basalis. Placenta divided into 15-30 lobules by septae from decidua basalis. Each cotyledon contains 2-4 tertiary villi and their branches.

Question 13

What is the route of fetal circulation?

Answer 13

Fetus drains to umbilical arteries, to chorionic arteries to villar capillaries, to chorionic veins, to umbilical vein, to fetus

Question 14

What is the route of maternal endometrial circulation?

Answer 14

Maternal blood to spiral arteries, to intervillous space, to endometrial veins.

Question 15

How many arteries and veins are in the umbilical cord?

Answer 15

2 arteries (go to mom), 1 vein (goes to fetus), in relation to fetal heart

Question 16

What are Hofbauer cells?

Answer 16

Large cells in extra embryonic mesoderm that are macrophages with large single cells located in the mesoderm.

Question 17

What is the placental barrier like in the first trimester?

Answer 17

Syncytiotrophoblast, Cytotrophoblast, Basal lamina of trophoblast, Fetal connective tissue (extra embryonic mesoderm), Basal lamina of fetal capillaries, Fetal endothelium

Question 18

What is the placental barrier like after twenty weeks?

Answer 18

Cytotrophoblast progressively disappears and connective tissue (extra embryonic mesoderm) thins. Barrier then becomes Syncytiotrophoblast (thin and few), Basal laminae, Fetal capillaries

Question 19

What is are the TORCH pathogens?

Answer 19

Things that can cross the placental barrier. Toxoplasmosis, Other (Parvo B19, Syphillis, VZV), Rubella, Cytomegalovirus, Coxsackievirus, HIV, Hepatitis B, Herpes simplex virus

Question 20

What are the main placental hormones?

Answer 20

HCG, Progesterone, Estrogen, Human placental lactogen (hPL), Prolactin, Prostaglandins, Relaxin

Question 21

What is HCG?

Answer 21

Human chorionic gonadotropin. Peptide produced by syncytiotrophoblast. Helps maintain corpus luteum and its production of progesterone and estrogen. Presence in maternal urine used for pregnancy tests. Present 6 days after fertilization.

Question 22

What is Progesterone?

Answer 22

By end of first trimester, progesterone secretion is sufficient to replace that produced by corpus luteum. Produced by syncytiotrophoblast.

Question 23

What is Estrogen?

Answer 23

Fetal adrenal gland produces androgen. Androgen converted to estrogen by syncytiotrophoblast.

Question 24

What is Human placental lactogen (hPL)?

Answer 24

Chorionic somatomammotropin (HCS). Peptide produced by syncytiotrophoblast. Affects growth, lactation, lipid and carbohydrate metabolism.

Question 25

What produces prolactin, prostaglandins and relaxin?

Answer 25

Produced by the decidua cells derived from the stromal connective tissue cells of the mother (Found in the decidua basalis)

Question 26

What is the function of Relaxin?

Answer 26

Softens pubic symphysis prior to parturition.