Embryologt

Question 1

Steps of fertilization (3)

Answer 1

1. Capacitation
2. Acrosome reaction
3. Fusion of the plasma membrane of sperm and oocyte

Question 2

Describe step 1 of fertilization

Answer 2

1. Capacitation
   Removal of seminal proteins from the surface
   Penetration through corona radiata

Question 3

Describe step 2 of fertilization

Answer 3

2. Acrosome reaction
   release of acrosomal enzyme
   penetration through zona pellucida

Question 4

Describe step 3 of fertilization

Answer 4

3. Fusion of membrane of sperm and oocyte

Changes in zona pellucida inactivates sperm receptors and prevents polyspermy

Question 5

Where does fertilization occur?

Answer 5

Ampulla of fallopian tube

Question 6

Describe fusion of sperm and oocyte

Answer 6

sperm and oocyte forms pronucleus of each, Then pronuclei fuses, restoring the normal diploid number. Then, mitotic division and cleavage begins

Question 7

What is blastomere?

Answer 7

identical daughter cells of zygote with same sizes

Question 8

Name for 16-32 blastomere

Answer 8

Morula (day3)

Question 9

What is blastocyst?

Answer 9

day 4-6 where fluid from uterine cavity fills the blastocystic cavity and inner cell mass/embryoblast is formed.

Question 10

what does inner cell mass develop into

Answer 10

inner cell mass > embryoblast > embryo

Question 11

What does peripheral cell develop into?

Answer 11

peripheral cell> trophoblast > fetal component of the placenta

Question 12

Where does implantation occur?

Answer 12

posterior wall of body of uterus close to the fundus

Question 13

After blastocyst implant on endometrium, trophoblasts differentiates into two layers. What are those?

Answer 13

inner layer of cytotrophoblast

outer layer of syncytiotrophoblast

Question 14

Role of cytotrophoblast

Answer 14

mitotically active, MAKE cells and contributes cells to the syncytiotrophoblast

Question 15

Role of syncytiotrophoblast

Answer 15

erode endometrial connective tissue enabling the blastocyst to “burrow” into endometrium for implantation.

Question 16

Relationship between syncytiotrophoblast with early pregnancy test

Answer 16

Syncytiotrophoblast secrete HCG human chorionic gonadotrophin which is detected at early pregnancy test.

Question 17

After implantation, embryoblast changed into embryonic disc which is made up of two layers. What are those?

Answer 17

1. Epiblast

2. Hypoblast

Question 18

Role of epiblast

Answer 18

thicker layer, consisting of columnar cells, forming 3 germ layers

Question 19

Role of hypoblast

Answer 19

small cuboidal cells, that become yolk sac

Question 20

What is gastrulation?

Answer 20

formation of three germ layers

Question 21

What happens to epiblast during gastrulation?

Answer 21

develop into trilaminar disc with three layers, endoderm mesoderm and ectoderm

Question 22

3 Groups of mesoderm

Answer 22

lateral, intermediate paraxial

Question 23

Intermediate mesoderm

Answer 23

urogenital organs and ducts

Question 24

Paraxial mesoderm

Answer 24

one, muscle, skin

Question 25

lateral mesoderm

Answer 25

heart, spleen, adrenals,