Placentation Flashcards
What is a placenta?
Transient endocrine organ interchange between the conceptus and dam
What is the placenta made of?
Fetal component derived from chorion and maternal component derived from the uterine endometrium
What are the functional units of the placenta?
chorionic villus
How are placentas classified?
According to the distribution of chorionic villi and by the intamacy
How are the chronionic villi distribution classified?
Diffuse, Cotyledonary, Zonary, Discoid
Name the species and the typeof chorionic villi distribution it has.
Sow-Diffuse Mare Diffuse Cow- Cotyledonary Ewe-Cotyledonary Dog-Zonary Human- Discoid
What is different between the mare and the sows diffuse placentas?
Mares has microcoteledonarys all over
What is placentome?
consists of a fetal cotyledon and maternal caruncle that originates in the caruncular regions
How many layers can change occur through?
7
How can someone determine if we are discussing the maternal or fetal side?
Prefix describes maternal and suffix describes fetal
What is the least intimate placenta?
Epitheliochorial found in the mare and sow
What does the BNCG secrete?
Placental lactogen and protein B
Describe the Diffuse villi distribution.
Velvet like surface, villi cover the entire surface
The mare has 5-10 endometrial cups. Describe their origin and where they are distributed.
Trophoblastic and endometrial origin.
Distributed over the surface of the placenta
What is the process of the endometrial cups?
Produce eCG between days 35 & 60 of pregnancy and are sloughed into the uterine lumen afterwards.
What days does the chorion initiate attachment of the caruncles to the uterus?
16 days in sheep
25 days in cattle
How are discoid placentas determined?
One or two distinct discs on one region of the chorion
Describe the epitheliochorial placenta.
Both the endometrial epithelium and the epithelium of the chorionic villi are intact. In sow and mare
What is different about the ruminants of the epitheliochoral placenta?
The endometrial epithelium can erode and become a syndesmochrial
What does BNGC make?
Estrogens and progesterone
When does Binucleate giant cells appear?
14 days in sheep
20 days in cows
Describe BNGC.
Originate from trophoblastic cells and may transfer complex molecules from the fetal to maternal complex
What is the most intimate placenta? What species has it?
Hemoendotheial
Rabbit
What purpose does the placenta serve during preganancy?
A Transient endocrine organ-hormones in the placenta circulate through fetal and maternal systems
Describe the purpose of the eCG at attachment.
Acts as a luteotropin for CL maintenance and of the accessory CL
eCG has a powerful FSH activity in all species except what?
Mare
Where and when is hCG made?
Found in primates it is made by the chorion after the blastocyst hatches from the ZP
When can hCG be detected?
In the blood and urine as early as 8 days
What would happen if a mare was high with eCG during pregnancy?
Ovulate between day 40-70
What is the P4 block?
When high levels of P4 inhibit myometrial contractions
Which animal needs the CL and which species don’t need it the whole pregnancy?
Sow and Rabbit need it
Ewe, mare and women don’t need the CL
What stimulates the growth of the fetus and mammary gland? What produces it?
Placental lactogen
Produced by binucleate cells
Where does relaxin originate?
From the ovary and placenta at birth
Aromatase makes androgens into what?
Estrogen
What three hormones cause contractions?
E2, PGF2a and Oxytocin
Fetus stress is caused by what?
Space limitations in the uterus
What does fetus stress cause the fetal AP to secrete?
ACTH that then stimulate production of corticosteroids
What are the layers of the placenta and which is the most and least intimate?
Hemoendothical- Most Intimate
Hemochorial
Endothelialchorial
Epitheliocorial- Least Intimate
What is another name for placental lactogen and what does it do?
Somammatotropin- Stimulates fetus and mammary gland growth
