01-22: Implantation

Question 1

When does fertilization occur in the upper ampulla?

Answer 1

within 12 hours after ovulation

Question 2

What stage of fertilization happens at the END OF DAY 1?

Answer 2

2-cell stage in isthmus

Question 3

What stage of fertilization happens at DAY 3?

Answer 3

• Morula in isthmus

- Corona radiata lost

Question 4

What stage of fertilization happens at DAY 4?

Answer 4

Blastocyst in uterus

Question 5

What stage of fertilization happens at DAY 5?

Answer 5

Loss of ZP

Question 6

What stage of fertilization happens at DAY 6?

Answer 6

Beginning of implantation

Question 7

The ZP surrounds the developing embryo until ____________________

Answer 7

the embryo reaches the uterus

Question 8

What is the process of shedding the ZP?

Answer 8

Blastocyst hatching

Question 9

ZP functions

Answer 9

-

Question 10

What are the 4 stages of implantation?

Answer 10

1- Expanded blastocyst attaches to the endometrial epithelium

2- Blastocyst penetrates uterine epithelium

3- Blastocyst invades the tissues underlying the epithelium

4- Maternal vascular supply is eroded

Question 11

What does the erosion of the maternal vascular supply do?

Answer 11

• creates spaces within the implanted material

- allows BV to bleed into the spaces so that the embryo can feed of the oxygen and nutrients for the next 9 months

Question 12

What is the initial contact of the expanded blastocyst to the endometrial epithelium?

Answer 12

initial contact between the endometrial surface and the embryonic pole of the blastocyst

Question 13

What is the embryonic pole of the blastocyst?

Answer 13

side of the blastocyst where the ICM is located

Question 14

What facilitates the attachment of the blastocyst to the endometrial epithelium?

Answer 14

Adhesion molecules expressed by:

• Endometrium
• Trophoblast

Question 15

What is the leukemia-inhibiting factor expressed by?

Answer 15

the endometrium

**respective receptors on the trophoblast may be important

Question 16

During blastocyst penetration into the uterine epithelium, what does the trophoblast separate into?

Answer 16

• Cellular cytotrophoblast

- Multinucleated syncytiotrophoblast

Question 17

What is the cellular cytotrophoblast closest to?

Answer 17

ICM

Question 18

What is the multinucleated syncytiotrophoblast closest to?

Answer 18

the endometrium

Question 19

Where does the syncytiotrophoblast projections penetrate?

Answer 19

the endometrial basal lamina

**then they begin to invade the endometrial stroma

Question 20

When do trophoblastic lacunae appear?

Answer 20

After the syncytiotrophoblast projections begin to invade the endometrial stroma

Question 21

What are the trophoblastic lacunae filled with?

Answer 21

Eroded endometrial BV with maternal blood

**Trophoblast = less invasive at this point

Question 22

What is the response of the endometrial stroma cells to the invading blastocyst called?

Answer 22

the decidual reaction

Question 23

Where are the decidual cells derived from?

Answer 23

endometrial stroma cells that accumulate glycogen and lipid droplets

Question 24

What is the result of the decidual reaction?

Answer 24

a massive cellular matrix completely surrounds the embryo and fills most of the endometrium

Question 25

During the decidual reaction, what do infiltrating leukocytes in the endometrium secrete?

Answer 25

IL-2

Question 26

What does IL-2 in the decidual reaction?

Answer 26

prevents the mother’s immune system from recognizing the embryo as a foreign body

Question 27

What is one of the primary functions of the decidual reaction?

Answer 27

provide an immunologically privileged site to protect the developing embryo from being rejected

Question 28

Where do ectopic pregnancies commonly occur?

Answer 28

Almost 80% = in uterine tube

0.2% - abdominal cavity
0.3% - cervical cavity
0.5% - ovary
1.0% - rectouterine pouch
2.0% - intestinal
17% - fimbrial
25% - isthmic
54% - ampullary

Question 29

What is an ectopic pregnancy?

Answer 29

when the fertilized egg develops outside the environment