Embryology

Question 1

What happens during the first week of development?

Answer 1

Fertilization, cleavage, and implantation

Question 2

What happens during the second week of development?

Answer 2

Period of 2: the embryoblast divides into the epiblast and the hypoblast; the trophoblast divides into the cytotrophoblast and the syncytiotrophoblast; two cavities are present, the amniotic cavity and the yolk sac

Question 3

What happens during the third week of development?

Answer 3

Period of 3: mesoderm differentiation; gastrulation (ectoderm, endoderm, and mesoderm); neurulation happens (neural plate, groove, and tube)

Question 4

What is gametogenesis?

Answer 4

It is a process by which the chromosome number is reduced by half, and the shape of the cell is altered, creating sperm and oocytes

Question 5

Where does fertilization happen?

Answer 5

In the ampulla of the uterine tube

Question 6

What are the phases of fertilization?

Answer 6

1. Capacitation and acrosomal reaction. 2. Penetration (of 3 layers). 3. Zona reaction

Question 7

What are the results of fertilization?

Answer 7

1. After the sperm penetrates the secondary oocyte, the ooctye completes meiosis 2, forming the ovum and the second polar body. 2. The sperm and ovum nuclei swell, forming pronuclei. 3. pronuclei approach each other and mitotic spindle forms between them. 4. Chromosomes of the pronuclei intermix, fertilization is accomplished. Then, the DNA replicates in preparation for the first cleavage division.

Question 8

What is the end product of fertilization?

Answer 8

The restoration of the normal diploid number of chromosomes and the determination of the chromosomal sex of the embryo

Question 9

Describe the process of cleavage?

Answer 9

1. Zygote
2. 4-cell stage
3. Morula
4. Early blastocyst
5. Implanting blastocyst

Question 10

Where is the site of implantation?

Answer 10

The posterior superior wall of the uterus

Question 11

What is an ectopic pregnancy?

Answer 11

It is a tubal pregnancy where the blastocyst implants within the ampulla. It is presented with uterine bleeding, sudden onset of abdominal pain (appendicitis), missed menstrual period, and and +HCG test

Question 12

What are the parts of the placenta?

Answer 12

Maternal: decidua basalis
Fetal: chorionic villi

Question 13

What is the function of the placenta?

Answer 13

It assists with gas exchange (oxygen, carbon dioxide), nutrient exchange (glucose, fatty acids, amino acids, and electrolytes), as well as hormonal and immunologic exchange.

Question 14

What is the result of endoderm folding?

Answer 14

The endoderm becomes enclosed inside the embryo forming the gut-tube

Question 15

What is the result of ectoderm folding?

Answer 15

The ectoderm covers the embryo from outside and amniotic sac expand to surround the embryo

Question 16

What is the process of limb development?

Answer 16

Limb buds develop from the ventrolateral body wall. The digital rays form notches which form webbed fingers which form separate digits.

Question 17

Which direction do the upper limbs rotate?

Answer 17

They rotate 90 degrees laterally

Question 18

Which direction do the lower limbs rotate?

Answer 18

They rotate 90 degrees medially

Question 19

What is amelia?

Answer 19

The absence of an entire limb

Question 20

What is meromelia?

Answer 20

The absence of part of a limb

Question 21

What is polydactyly?

Answer 21

Extra digit(s)

Question 22

What is syndactyly?

Answer 22

The fusion of digits``

Question 23

What separates maternal blood and fetal blood during the later stages of pregnancy?

Answer 23

The syncytiotrophoblast and fetal endothelium

Question 24

What must degenerate for blastocyst implantation to occur?

Answer 24

The zona pellucida

Question 25

What is the placenta previa?

Answer 25

It occurs when an implanted embryo is near the internal os of the pregnancy

Question 26

What are the two components of the placenta?

Answer 26

Chorionic villi and decidua basalis

Question 27

What is the purpose of chorionic villi?

Answer 27

They serve as finger like projections that insert themselves into the uterus

Question 28

What are somites?

Answer 28

They surround the notochord and differentiate to form the vertebral column, along with the vertebral muscle skin. They will give sclerotome, myotome, and dermatome