Embryology 1

Question 1

What are congenital disorders?

Answer 1

Birth defects, either structural or functional (eg metabolic disorder)

Question 2

What are the possible origins of congenital disorders?

Answer 2

Genetic, infectious, nutritional and/ or environmental in origin

Question 3

What are the periods of human embryology?

Answer 3

1. EGG(conceptus) :From fertilization to end of 2nd week
2. Embryo: Beginning of 3rd week to end of 8th week
3. Fetus: 3rd month to birth

Question 4

Name the first 3 steps of embryology and explain them.

Answer 4

1. Ovulation: A secondary oocyte is released from the ovary and swept into the oviduct
2. Fertilization: A single sperm penetrates the secondary oocyte. Eventually, the sperm and egg nuclei will fuse, resulting in a fertilized egg, or zygote.
3. Cleavage: The zygote soon undergoes rapid mitotic cell divisions as it moves along the oviduct toward the uterus, becoming a pre-embryo that consists of two cells, then four, eight and so on.

Question 5

Name the LAST 3 stages of embryology and explain them:

Answer 5

1. Morula: By day 4, successive divisions produce a morula, a solid ball of cells that enters the uterus
2. Blastocyst: By day 6, the pre-embryo becomes a blastocyst, a hollow ball of cells with a fluid-filled cavity. The blastocyst has freed itself from the zona pellucida and can increase in size.
3. Implantation: the blastocyst attaches to the uterine lining (endometrium) and begins to digest its way inward. The cells of the inner cell mass begin to form primary germ layers