Embryology and Gestational Development

Question 1

What period of gestation do we refer to as the pre-embryonic stage?

Answer 1

First two weeks of gestation

Question 2

What period during gestation do we refer to a developing human as an embryo?

Answer 2

Weeks 3-8

Question 3

At what point is a developing human considered a fetus?

Answer 3

Week 9-birth

Question 4

At what point during gestation are all organ systems structured?

Answer 4

Week 9

Question 5

What development events occur during weeks 1-2 of human development?

Answer 5

• Cellular division
• Migration
• Differentiation
• Gastrulation

Question 6

During what weeks of human development do Spina bifida and cerebral palsy begin to develop?

Answer 6

Weeks 1-2

Question 7

Explain the cellular divisions that occur during the first week.

Answer 7

• An unfertilized oocyte is released
• The oocyte is fertilized by sperm
• The fertilized oocyte splits into two-cells
• The cell differentiates into 4 cells
• The cell differentiates into 8 cells
• The cell differentiates into 16 cells and is now known as the Morula
• The cell differentiates again into 70-100 cells known as an embryoblast (the inner cavity is known as a blastocysts/blastocoel)
• The embryo hatches by shedding the zona pellucida
• The blastocyst rotates and implants into the endometrium of the uterus

Question 8

Explain an Ectopic pregnancy.

Answer 8

when a fertilized egg implants and grows outside the main cavity of the uterus (ex: a fertilized egg implants into the fallopian tube)

Question 9

What are the symptoms of a ectopic pregnancy?

Answer 9

• lateral pelvic pain
• blood and discharge

Question 10

Explain Gastrulation

Answer 10

• Occurs during the 3rd week of embryonic development
• Epiblast and hypoblast cells undergo a highly differentiated process called gastrulation
• During this process, the two cell layers become three germ cell layers, and the bodily axes observed in the mature adult are created

Question 11

What structures are derived from the endoderm?

Answer 11

• Epithelial lining of digestive and respiratory tracts
• Lining of urethra, bladder and reproductive system
• Liver and Pancreas

Question 12

What structures are derived from the mesoderm?

Answer 12

• Notochord (vertebrae)
• Musculoskeletal system
• Muscular layer of stomach, intestine, etc.
• Circulatory system

Question 13

What structures are derived from the ectoderm?

Answer 13

• Epidermis of skin
• Cornea and lens of eye
• NERVOUS SYSTEM