Lecture 21- Placentation

Question 1

Placentation

Answer 1

formation of the placenta- transient organ of pregnancy

Question 2

functions of the placenta

Answer 2

fetal/maternal exchange

• nutrients, gases, waste and hormones
• facilitate diffusion and active transport

Endocrine gland

• progesterone, estradiol, placental lactose, glycoprotein, eCG, hCG
• hormones are important for both mother and baby

protection
- physical and biological

Question 3

Components of Placenta

Answer 3

embryonic/fetal- extraembryonic membranes
- starts to form before implantation in domestic species

maternal - endometrium
- forms by differentiation of endometrial cells during implantation

Question 4

Implantation

Answer 4

penetration of the conceptus into the endometrium
- true implantation occurs in primates and rodents

in domestic species, the term is used for attachment of the conceptus in the endometrium. the conceptus stays the whole time in the uterine lumen

• requires apposition and attachment of the conceptus and endometrium
• different presentation of implantation across species
• allow completion of placentation

Question 5

Nutrition of Conceptus

Answer 5

pre- and peri-implantation: histotroph –> vitamins, nutrients etc.
- becomes a limitation with eh development of the conceptus

post implantation with functional placenta: haemotroph
- allow exchange of nutrients, hormones, gases, and waste between fetal and maternal blood circulation

Question 6

Primate Embryo Implantation

Answer 6

due to the invasive nature of the trophectoderm in these species, the conceptus penetrates the epithelium and invade

Question 7

Primate Embryo Implantation

Answer 7

due to the invasive nature of the trophectoderm in these species, the conceptus penetrates the epithelium and invade the endometrial connective tissue is which it becomes completely embedded

Question 8

Types of Placenta - According to distribution of chorionic villi

Answer 8

1. cotyledonary
2. zonary
3. diffuse
4. discoid

Question 9

Types of Placenta- according to integrity of the endometrium structure and number of placental layers separating maternal and fetal blood

Answer 9

1. epithelio-chorial - 6 layers - 3 fetal +3 maternal
2. synepithelio-chorial - 5-6 layers 2-3 maternal
3. endothelial-choral - 4-5 layers 1-2 maternal
4. hemo-chorial- 3 layers - 0 maternal