implantation basics

Question 1

What is the definition of pregnancy?`

Answer 1

After fertilisation when the conceptus succesfully signals its presence to the mother, and continues to develop succesfully in the mother’s uterus

Question 2

What is the definition of fertilisation?

Answer 2

The fusion of 2 haploid gametes to form a diploid zygote

Question 3

What is the definition of infertility?

Answer 3

After 1 year of regular, unprotected sex - the women has not become pregnant.

Question 4

What is the incidence of infertility in the UK?

Answer 4

1/6

Question 5

At what region of the fallopian tubes does 4-8 cell cleavage occur?

Answer 5

Isthmus

Question 6

What are 3 crucial requirements for implantation?

Answer 6

• receptive endometrium (Window of implantation)
• healthy embryo at blastocyst stage
• mutual communicatio bt mother and embryo

Question 7

What are the three stages of implantation, and on what days do they occur?

Answer 7

• apposition, Day6/7
• adhesion, Day 7/8
• invasion, Day 8/9

Question 8

What cell structure is found opposite the uterine epithelium at apposition?

Answer 8

Inner cell mass

Question 9

What happens during gastrulation?

Answer 9

Spherical blastocyst changes to hollow cup shaped structure with 3 layers of cells. These cells form the germ layers of the embryo.

Question 10

What are the 3 germ layers of the embryo?

Answer 10

Ectoderm, endoderm and mesoderm

Question 11

What is the cell potential of ectoderm cells?

Answer 11

Skin, neurons, pigments

Question 12

What is the cell potential of endoderm cells?

Answer 12

Digestive tract, lungs, thyroid

Question 13

What is the cell potential of mesoderm cells?

Answer 13

muscle, kidney tubules, red blood cells

Question 14

Through histological tests you find the endometrium of a woman has long apical microvilli and a highly negative surface charge. Will this woman have succesful embryo implantation?

Answer 14

No - her endometrium is not in a receptive state

Question 15

When do pinopodes form?

Answer 15

During day 19-21, in the window of implantation. Pinopodes assist blastocyst invasion of endometrial epithelium

Question 16

What is decidualisation?

Answer 16

Decidualisation is the change of uterina stroma cells to become receptive to blastocyst invasion

Question 17

What specific changes occur during decidualisation?

Answer 17

Uterine stroma differentiate from elongated fibroblast like mesenchymal cells to rounded epithelioid like structures.

Question 18

What unique abilities do decidualised stroma have that non decidualised stroma don’t?

Answer 18

They can regulate trophoblast invasion by resisting inflammation and oxidative attacks, and dampen the maternal immune system.

Question 19

Which cells in the endometrium are stimulated by estradiol?

Answer 19

Endometrial epithelial cells

Question 20

Which cells in the endometrium are stimulated by progesterone?

Answer 20

Uterine stroma cells.

Question 21

What is the effect of a progesterone receptor antagonist (less than 7 weeks)?

Answer 21

Abortive

Question 22

At what point in pregnancy does progesterone supply change from corpus luteum to placenta?

Answer 22

12 weeks

Question 23

What role does hCG have in progesterone regulation?

Answer 23

hCG prolongs progesterone secretion

Question 24

Where is hCG produced?

Answer 24

In early embryo produced by trophoblast cells, later secreted by the placenta.

Question 25

What is the role of MMPs?

Answer 25

proteolytic enzymes involved in tissue degradation

Question 26

What is the role of TIMPs?

Answer 26

Tissues specific inhibitor or MMPs