Placentation

Question 1

Yolk Sac

Answer 1

-Origin: early endodermal layer
-Function: vestigial
-A membranous sac that provides early nourishment for the developing embryo in some animals
-picks up uterine secretions from endometrium to stimulate early embryonic development

Question 2

Amnion

Answer 2

-Origin: cavitation from inner cell mass and results from the folding and fusion of the chorion
-Function: encloses fetus in a fluid filled cavity
-The innermost membrane that encloses the embryo and produces amniotic fluid
-prevents fetus from injury, provides lubrication for parturition, reservoir for urine and waste
-prevents the lungs from collapsing and opens digestive tract

Question 3

Allantois

Answer 3

-Origin: Diverticulum of hindgut
-Function: blood vessels connect fetal with placental circulation
-A membrane involved in waste elimination and gas exchange in the developing embryo
-Fuses with chorion (chorio-allantoic placenta), carries blood vessels of placenta, reservoir for nutrients and waste
-Umbilical cord attaches the fetus to the allantois
-Fills with fluid to expand the chorio-allantois against the uterine wall

Question 4

Chorion

Answer 4

-Origin: trophoblastic capsule of blastocyst
-Function: encloses embryo and other fetal membranes intimately associated with lining of uterus to form placenta
-One of the fetal membranes that, along with the allantois, forms the fetal part of the placenta
-Attaches to the uterus, absorbs nutrients from the uterus, allows maternal/fetal gas exchange, and produces hormones

Question 5

Chorio-Allantois

Answer 5

The combined fetal membranes (chorion and allantois) responsible for gas exchange and nutrient transfer in some species.

Question 6

Caruncle

Answer 6

The raised, fleshy structure in the ruminant uterus that forms the material side of the placenta.

Question 7

Cotyledon

Answer 7

-The corresponding structure on the fetal side of the ruminant placenta that interfaces with the caruncle

Question 8

Placentome

Answer 8

-The functional unit formed by the attachment of caruncles and cotyledons in ruminant placentas

Question 9

Know the days of gestation at which the placenta attaches to the uterus for the cow

Answer 9

30-35 days

Question 10

Know the days of gestation at which the placenta attaches to the uterus for the sow

Answer 10

12-20 days

Question 11

Know the days of gestation at which the placenta attaches to the uterus for the ewe

Answer 11

18-20 days

Question 12

Know the days of gestation at which the placenta attaches to the uterus for the mare

Answer 12

50-60 days

Question 13

Diffuse Placenta

Answer 13

-sow vs mare
-a type of placental organization where there’s no clear distinction between maternal and fetal tissues throughout the entire placenta in some species
-such as pigs and horses.

Question 14

Zonary placenta

Answer 14

-A type of placenta forming a band-like structure around the fetus
-as seen in carnivores like dogs and cats

Question 15

Discoid placenta

Answer 15

-A type of placenta with a disc-shaped structure found in primates and rodents

Question 16

Cotyledonary placenta

Answer 16

-ruminants
-where maternal caruncles and fetal cotyledons form attachment sites

Question 17

Know the characteristics of fetal nutrition in farm animals.

Answer 17

-Blood gas exchange at chorion- endometrium attachment.
-Placenta highly permeable to water and electrolytes (stored in and exchange between allantoic and amniotic fluids)
-Placenta converts glucose to fructose. Allows storage in allantoic fluid.
-Fetal fat formed from fatty acids transferred across the placenta.
-Fetus makes protein from transferred amino acids.
-Water soluble vitamins cross the placenta easier than fat soluble vitamins
-Minerals are transferred across the placenta.
-In domestic species antibodies to fight disease do not cross the placenta as the newborn will get these antibodies from the first milk (Colostrum)