Implantation And Formation Of Placenta

Question 1

Decidualization is under the influence of?

Answer 1

Progesterone and Oestrogen

Question 2

After implantation, endometrial cells become larger and accumulate more nutritive substances. Which substances are these?

Answer 2

Glycogen, lipids, GAGs

Question 3

What are the 3 regions of decidua

Answer 3

Basalis, capsularis and parietals

Question 4

Decidua basalis?

Answer 4

Found between implanted blastocyst and myometrium

Question 5

Decidua capsularis

Answer 5

Covers the implantation site and bulge of blastocyst, separates it from uterine cavity

Question 6

Parietalis

Answer 6

The remainder of the uterine lining

Question 7

What are the 3 stages of implantation

Answer 7

Apposition
Adhesion
Invasion

Question 8

Where specifically is the site of implantation?

Answer 8

Usually body of uterus, upper part of posterior wall near the midline

Question 9

Three things happen in the week of 2s. What are they?

Answer 9

Formation of bilaminar disc from embryoblast, epiblast and hypoblast

Formation of 2 cavities. Amniotic cavity related to epiblast and primary yolk sac related to hypoblast

Trophoblast differentiates into 2 layers. Cytotrophoblast(stem cell layer) and synctitiotrophoblast(functional layer)

Question 10

When does extraembruonic mesoderm form and when?

Answer 10

At the end of the second week and in between the heuser membrane and inner cytotrophoblast

Question 11

What is the chorion?

Answer 11

Trilaminar tissue consisting of outer synctiotrophoblast, middle cytotrophoblast and inner extraembryonic mesoderm

Question 12

Primary yolk sac is also known as

Answer 12

Exoceolomic cavity

Question 13

How is the chorionic cavity or extraembryonic coelom formed?

Answer 13

Formed by large cavities which develop in the extraembryonic mesoderm qnd become confluent. Surround primitive yolk sac and amniotic cavity except where germ disc is connected to the trophoblast by connecting stalk

Question 14

Which space is encroached by enlarging amniotic cavity during lateral folding of the embryo

Answer 14

Extraembryonic coelom or chorionic cavity

Question 15

What are the types of chorion

Answer 15

Frondosum - Rough chorion(which grows into the decidua basalis)
Laeve - Smooth chorion which grows into decidua capsularis

Note. By week 20, chorion leave and decidua capsularis come into complete contract with decidual oarietalis to form amniochorion

Question 16

Which membrane ruptures during delivery of baby

Answer 16

Amniochorion

Question 17

Fetal part of placenta develops form… and maternal part develops from.
.

Answer 17

Chorionic sac(chorion frondosum)
Endometrium(decidua basalis)

Question 18

What makes chorion frondosum(rough chorion) appear rough

Answer 18

presence of finger like projections called chorionic villi

At first forms a sac which surrounds embryo/foetus

Question 19

3 developmental types of chorionic villi

Answer 19

Primary
Secondary
tertiary

Question 20

Structural types of chorionic villi

Answer 20

Stem : Attached to chorionic plate
Anchoring : Attached to nasal plate
Intermediate : branches from stem villi
Terminal or floating : blind ending no branches, site for feto maternal exchange

Question 21

What is the placental barrier?

Answer 21

Structures across which other substances must diffuse from intervillous space to foetal capillary
6 layers in early placenta and 3 in late
Reduction achieved by syncytial knots(aggregate syncytial nuclei)

Question 22

What are the 6 layers of early placenta

Answer 22

Synctiotrophoblast, cytotrophoblast, basement membrane of trophoblast, mesenchyme, basement membrane of villous(fetal capillary), fetal capillary endothelium

Question 23

What are the 3 layers of late placenta

Answer 23

Synctiotrophoblast, fused foetal and villus basement membranes, and foetal capillary endothelium

Question 24

Interchange occurs between foetal capillaries and chorionic vessels….

Answer 24

Foetal capillaries join to form chorionic vessels

Chorionic vessels join to form umbilical vessels

Question 25

Where in the placenta does maternal blood flow into

Answer 25

Intervillous spaces