Placenta

Question 1

What is a transient endocrine organ and produces a variety of hormones that enter maternal and fetal blood supply?

Answer 1

Placenta

Question 2

What are the major function untis of the placenta?

Answer 2

Chorionic villi

Question 3

What are chorionic villi?

Answer 3

Major functional unit of placenta - projection on the surface of the chorion that intimately interact with maternal tissue

Question 4

What is placenta classification based on

Answer 4

Chorionic villi distribution

Question 5

What is placenta classification “diffuse”?

Answer 5

Chorionic villi located over the entire uterine luminal epithelium

• pig and horse

Question 6

How is the pig placenta classification?

Answer 6

Diffuse placenta that is velvety in appearance with closely spaced chorionic villi

Question 7

What is the horse placenta classification?

Answer 7

Organized as microzones of villi named microcotyledons.

Microtyledons are distributed over the entire surface of the chorion as discrete regions of fetal maternal interfaces

Question 8

What is mare unique specialization?

Answer 8

Unique to mare is presence of endometrial cups derived from narrow band of thick trophoblast that develop around fetus

Question 9

What does the mare chorionic girdle begin?

Answer 9

~d25

Question 10

What occurs at ~d40 of mare endometrial cups?

Answer 10

Girdle peels off fetal membranes and trophoblast invade the endometrium to form the cups and produc eCG

Question 11

What occurs to mare endometrial cups at ~d70?

Answer 11

They begin to be destroyed due to maternal immune attack

Question 12

What is cotyledonary?

Answer 12

Chorionic vascularized villous trophoblasts and uterine endometrial structures termed caruncles come together like a spot weld

• ruminants

combined structure called placentomes

Question 13

What occurs at ~30d in sheep and ~36d in cattle?

Answer 13

Villous processes of trophoblast form in the chorionic membrane opposite the caruncular tissue.

Question 14

What does further branching of the villi in cotyledonary help?

Answer 14

Further branching of the villi helps the trophoblast fit into the caruncular tissue - fingers into a glove

Question 15

How does Cow, giraffe cotyledonary differ from sheep, goat?

Answer 15

Cow and giraffe - Convex

Sheep and goat - Concave

Question 16

What is difference between zonary and discoid placenta classification based on chorionic villi distribuition?

Answer 16

Zonary - an invasive band of the chorion surrounds the middle of the fetus (dog and cat)

Discoid - a disc-like structure of chorion interacting with maternal tissue ( higher primates and rodents

Question 17

What occurs to chorioallantoic placenta at ~18d cats and ~20d in dogs?

Answer 17

Chorion fuses with allantois

• zonal villi invade the endometrium with some villi pushing into gland openings
• maternal blood vessels become completely surrounded by trophoblast

Question 18

Four placenta classifications based on cell layers at maternal-fetal interface?

Answer 18

Epitheliochorial

Syneptheliochorial

Endotheliochorial

Hemochorial

Question 19

Epitheliochorial?

Answer 19

Least invasive as epithelium of chorionic villi and uterine luminal epthelium are intact

6 - layers

Capillary wall

Basement Membrane

Endometrium Layer

Chorion

Basement Membrane

Capillary Wall

Question 20

What are the 6 layers of epitheliochorial starting at maternal side?

Answer 20

Capillary wall

Basement Membrane

Endometrium Layer

Chorion

Basement Membrane

Capillary Wall

Question 21

Synepitheliochorial?

Answer 21

Specialized binucleate giant trophoblast cells (BNGC) migrate into the uterin epithelium

6 layers

Question 22

Synepitheliochorial

1 Cows

2. Sheep and goats

Answer 22

1. Cows trinucleated cells are formed but are short lived
2. Continued production of binucleate trophoblast can produce an extensive fetal-maternal syncytial layer

Question 23

What is placental lactogen?

Answer 23

Hormone important in mammary gland development for prodcution of lactose

Question 24

Endotheliochorial?

Answer 24

Trophoblasts move through uterin epithelium, stroma and are in contact with maternal endothelia (cats, dogs)

5 layers

Question 25

Hemochorial?

Answer 25

Highly invasive trophoblast pass through the maternal uterine epithelium, stroma and endothelium of maternal vasculature becoming directly in contact with maternal blood - rodents, higher primates

Question 26

5 functions partially or completely accomplished throughout pregnancy?

Answer 26

Gastrointestinal (fetal nutrition) Endocrine (Hormone/enzyme production) Respiratory (Transfer of O2 and CO2) Renal (Hormone/Enzyme Production) Relatively Uncharacterized (Immunologic Functions)

Question 27

5 forms of plactenal transport?

Answer 27

Simple Diffusion - gasses and simple molecules Facilitate diffusion - glucose, carrier system operates with a chemical gradient Active transport - essential a.a., water soluble vitamins; maintain higher concentration in fetus than in mother Receptor-mediated endocytosis - immune bodies, protein and fat Leakage - intact cells

Question 28

What does the umbilical cord consist of?

Answer 28

Surrounds two umbilical arteries Surrounds two umbilical veins Urachus Vestige of yolk sac

Question 29

How do the umbilical arteries move within umbilical cord?

Answer 29

Move in spiral pattern around the urachus giving off branches to the amniotic sac and ending in chorioallantoic membrane