Embryology-Fertilization

Question 1

Polyspermy Block

Answer 1

Changes that occur from the interaction of the oocyte and sperm cell.
Prevents the diandric tiploidy, in theory.

Question 2

Male Pronucleus

Answer 2

Sperm nuclear contents

Question 3

Syngamy

Answer 3

The successful completion of fertilization, forming a zygote.
Zygote lasts only few hours; terminates in first cleavage division.

Question 4

Describe cleavage.

Answer 4

1. series of mitotic divisions of zygote.
2. A holoblastic process (cells divide completely thru their cytoplasm)
3. Asymmetrical and Asynchronous.
4. Forms blastula.

Question 5

What is a blastula?

Answer 5

Consists of blastomeres.

Question 6

Morula?

Answer 6

A cluster of blastomeres. Formed by cleavage from the single-celled zygote.

Question 7

Totipotency

Answer 7

A stem cell that can differentiate into every cell within the organism.

Question 8

Pluripotency

Answer 8

Stem cell that differentiates into ecto-, meso-, endoderm

Question 9

What happens in the secretory phase?

Answer 9

Blastocyst implants into the functional layer of endometrium.

Question 10

Implantation process

Answer 10

1. Zona pellucida degenerates
2. blastocyst implants in posterior superior wall of uterus.
3. secretory phase.
4. Trophoblast differentiates into cytophoblast syncytiotrophoblast.

Question 11

Cortical Reaction

Answer 11

Occurs after zona pellucida is penetrated. Releases lysosomal enzymes that change cell membrane potential. Inactivates sperm receptors.

Question 12

Stages of Embryogenesis

Answer 12

1. Cleavage
2. Gastrulation
3. Organogenesis

Question 13

Cleavage

Answer 13

Cell division of the zygote to become the blastula

Produce germ layers

Question 14

What are the germ layers?

Answer 14

Ectoderm, endoderm, mesoderm

Question 15

What is organogenesis.

Answer 15

Differentiation of germ layers to form all body organs.

Question 16

Peg Cells

Answer 16

Secrete watery type of fluid to move egg towards the uterus.

Question 17

Difference of Embryology and teratology.

Answer 17

Teratology: Study of abnormalities of physiological development.
Embryology: development of embryo, from fertilization of ovum to the fetus.

Question 18

Major events in Fertilization.

Answer 18

1. Contact/Recognition of sperm and egg.
2. Regulation of sperm into the egg. Only one can enter.
3. Fusion of genetic material.
4. Activate egg’s metabolism to start development.

Question 19

Clinical considerations associated with Week 1 of development

Answer 19

1. twinning.

2. ETP. ectopic tubal pregnancy

Question 20

Ectopic Pregnancy

Answer 20

Implantation of blastocyst outside the uterine cavity

Question 21

Embryoblast

Answer 21

• inner cell mass

- differentiates into epiblast and hypoblast

Question 22

Trophoblast

Answer 22

-differentiates in to cytotrophoblast and syncytiotrophoblast during implantation.

Question 23

Syncytiotrophoblast

Answer 23

• grows to reach endometrial blood vessel
• Does not mitotically divide
• produce hCG

Question 24

Cytotrophoblast

Answer 24

• mitotic division, adding size

- produce chorionic villi

Question 25

Extraembryonic Somatic Mesoderm

Answer 25

- line cytotrophoblast. - form connecting stalk - covers amnion

Question 26

Chorion

Answer 26

-formed by extraembryonic mesoderm, cytotrophoblast, and syncytiotrophoblast

Question 27

Prochordal Plate

Answer 27

- formed by epiblast and hypoblast | - future site for mouth