Lecture 2: Prenatal Development

Question 1

What are the 3 stages of prenatal development

Answer 1

• Germinal Period: Conception to implantation.
• Period of the Embryo: Implantation to approximately 2 months.
• Period of the Fetus: 2 months to birth.

Question 2

Germinal Period: Morula

Answer 2

A solid cluster of cells resulting from the division of a fertilized egg.

Question 3

Germinal Period: Blastocyst

Answer 3

A hollow ball of cells that implants in the uterine wall.

Question 4

Embryo @3 weeks

Answer 4

Early organ formation begins.

Question 5

Embryo @7 weeks

Answer 5

Further development of organ systems.

Question 6

Fetus @2 months

Answer 6

Major organ systems are established.

Question 7

Fetus @4 months

Answer 7

Development of sensory abilities like touch, hearing (250-500 Hz), and movement.

Question 8

Fetus @8 months

Answer 8

Rapid growth and preparation for birth

Question 9

Variations from Typical Development: Environmental Factors

Answer 9

• Toxins: Includes substances like thalidomide, alcohol, radiation, and pesticides.
• Nutrition: Folic acid is critical for preventing neural tube defects.

Question 10

Variations from Typical Development: Genetics

Answer 10

Examples: Cystic fibrosis, sickle-cell anemia, and chromosomal disorders.

Question 11

Chromosomal Variations: Chromosomal Abnormalities

Answer 11

Having fewer or more than 46 chromosomes, often incompatible with life but with exceptions.

Question 12

Chromosomal Variations: Aneuploidy

Answer 12

Abnormal number of chromosomes, leading to developmental issues.
examples include:
* Trisomy 21 (Down Syndrome): Intellectual disabilities and physical abnormalities.
* Trisomy 18 (Edwards Syndrome): Severe developmental delays.
* Trisomy 13 (Patau Syndrome): Congenital malformations.

Question 13

Sex Chromosome Variations

Answer 13

Variability in sex chromosome numbers can lead to ambiguous genitalia or secondary sex characteristics.
There are more than two biological sexes based on chromosomal variations.

Question 14

Teratogens

Answer 14

Definition: Agents causing congenital malformations.
Examples:
* Thalidomide: Causes limb deformities.
* Fetal Alcohol Syndrome (FAS): Microcephaly and sensory impairments.

Question 15

The Thalidomide Tragedy

Answer 15

Developed in 1954 to treat morning sickness but led to severe limb deformities in over 20,000 children globally.
Prevented in the U.S. due to efforts by Dr. Frances Oldham Kelsey.

Question 16

Fetal Alcohol Syndrome (FAS) features

Answer 16

• Microcephaly: Abnormally small head.
• Vision and hearing impairments.

Question 17

Fetal Learning: DeCasper & Spence (1986) & Hepper (1991)

Answer 17

• DeCasper & Spence (1986): Demonstrated that fetuses can recognize stories read prenatally (e.g., “Cat in the Hat”). Testing at ~2.5 days post-birth showed preference for familiar stories.
• Hepper (1991): Explored learning before and after birth with neighbours song