Embryology

Question 1

The first two weeks of prenatal development is known as the

Answer 1

Pre-embryonic period

Question 2

How do you define the foetal period?

Answer 2

From week 9 of development until birth

Question 3

A fertilised ovum is known as a

Answer 3

Zygote

Question 4

The specialised extracellular matrix that surrounds the developing oocyte is known as the

Answer 4

Zona pellucida

Question 5

List some of the functions of the Zona pellucida

Answer 5

1. Provides nutritional and mechanical support to the oocyte
2. Helps in binding of sperm
3. Protmotes acrosomal reaction
4. Prevents polyspermy

Question 6

List the four outcomes of fertilisation:

Answer 6

1. Restores normal diploid number of chromosomes (46)
2. Secondary oocyte completes meiosis
3. The sex of the embryo is established
4. Initiation of cell division (cleavage)

Question 7

The rapid mitotic division of cells in a zygote is known as

Answer 7

Cleavage

Question 8

What is the outcome of “cleavage?”

Answer 8

• Zygote undergoes rapid cell divisions with no overall growth, producing a cluster of cells.
• Different cells derived as a result of cleavage are called blastomeres
• Result is a compact mass/ball of cells called a morula

Question 9

When is the “embryonic period?”

Answer 9

Weeks 3-8

Question 10

What is the significance of the embryonic period?

Answer 10

Most of the organ systems are developed

Question 11

What are the normal sites of implantation of the embryo?

Answer 11

The fundus of the uterus, posterior wall of the uterus, sometimes the side walls

Question 12

What is the outcome of implantation of the embryo in the fallopian tubes?

Answer 12

Ectopic pregnancy

Question 13

What are the names of the three major germ layers in an embryo?

Answer 13

Endoderm, mesoderm, ectoderm