Lecture 11

What is the composition of the placenta?

It is made up of maternal uterine tissue and fetal extra-embryonic membranes.

What are the main functions of the placenta?

The placenta exchanges gas and nutrients between the dam and fetus, and removes fetal waste. It acts as an endocrine organ that produces hormones necessary for pregnancy.

True or false: all domestic animals have a chorioallantoic placenta

True

Is there a mixing of blood between the mother and fetus?

No, there is no mixing of blood.

What are the three types of physical barriers between maternal and fetal circulations?

Epitheliochorial, endotheliochorial, and hemochorial.

What distinguishes the epitheliochorial placenta. Which animals have this?

is that it has all six tissue layers separating maternal and fetal blood. This includes the maternal uterine epithelium and chorionic epithelium.

Horses and pigs

What distinguishes the endotheliochorial placenta. Which animals have this

It lacks the uterine epithelium and the uterine connective tissue layer in between the foetal and maternal layers (still has connective tissue but just not between the layers as much)

Carnivores

What distinguishes the hemochorial placenta? Which animals have this

There is no uterine epithelium, connective tissue, or uterine endothelium between the two layers

Primates and rodents

What is the synepitheliochoral/syndesmochorial placenta? Which species is this found in

Trophectodermal binucleate cells migrate into the endometrial epithelium and fuse with these cells to form syncytia to varying degrees

Found in sheep and goats and cows

Which animals have the most surface area for a functional placenta?

Pigs and horses.

What type of placenta do ruminants have?

Cotyledonary placentas.

Which type of placenta is found in monkeys, humans, and rodents?

Discoid placentas.

What type of placenta do cats and dogs have

Zonary area

What is the configuration of chorionic attachment to the maternal epithelium in pigs

Folded is where you have folds and troughs, rugae and fossae

What type of chorionic attachment do horses and ruminants have?

Villous attachment where you have chorionic villi with endometrial crypts or septa

Which type of attachment is characterized by chorionic villi or lamellae and found in dogs?

Labyrinthine attachment.

What is the labyrinthine zone and the junctional zone in dog chorionic attachment

LZ = The labyrinthine zone has trophoblastic lamellae where the cytotrophoblasts and the syncytial trophoblasts cover the maternal vessels

JZ = the area of transition between the gland zone and the labyrinth zone

What defines a deciduate placenta?

Maternal tissue is lost when the placenta is expelled after birth. Erosion of maternal epithelium occurs

What distinguishes a non-deciduate (adeciduate) placenta?

Maternal tissue is not lost when the placenta is removed after birth.

Which species are partial deciduates

Ruminants