Chapter 3: Intro to prenatal development

Question 1

What is a karyotype?

Answer 1

Photographic analysis of the orderly arrangement of the 46 chromosomes of the zygote

Question 2

Zygote undergoes mitosis or cleavage resulting in what?

Answer 2

A small ball of cells: MORULA

Question 3

What occurs after the Morula is formed?

Answer 3

Morula continues to divide via cell division and becomes a BLASTOCYST

Question 4

After 1 week of dividing, what does the blastocyst consist of?

Answer 4

Trophoblast layer (future prenatal support tissue)
Embryoblast layer (future embryo)

Question 5

What is Patterning and what does it consists of?

Answer 5

Physiological processes that occur during the embryonic period. It consists of: Induction, proliferation, differentiation, morphogenesis, maturation

Question 6

What occurs during week 2?

Answer 6

Bilaminar embryonic disc is developed

Question 7

What does the bilaminar embryonic disc consist of?

Answer 7

Superior epiblast layer - high columnar cells
Inferior hypoblast layer - small cuboidal cells

Question 8

What occurs during week 3? (7)

Answer 8

• Formation of the primitive streak
• Mesoderm layer is formed
• Trilaminar embryonic disc is formed: mesoderm endoderm, ectoderm
• Disc develops the cephalic end where the oropharyngeal membrane is formed
• CNS begins to develop (brain and spinal cord)
• Neural plate is developed and becomes the neural groove which becomes the neural tube
• Somites form through the mesoderm

Question 9

What gives the disc bilateral symmetry?

Answer 9

Primitive streak

Question 10

How does the primitive streak form?

Answer 10

It forms within the embryonic disc, through increased cell production at the midline area

Question 11

How is the mesoderm formed?

Answer 11

Cells from the epiblast layer move or migrate toward the hypoblast layer (only in the area of the primitive streak). This layer becomes the MESODERM

Question 12

That layers are in the trilaminar embryonic disc

Answer 12

Mesoderm, endoderm, ectoderm

Question 13

What is the oropharyngeal membrane

Answer 13

Location of the future primitive mouth or stomodeum and marks the beginning of the digestive tract

Question 14

What is the neuroectoderm

Answer 14

group of specialized cells that differentiates fromthe ectoderm

Question 15

What is the neural plate

Answer 15

central band of cells extending from the cephalic end to the caudal end

Question 16

What happens to the neural plate?

Answer 16

Plate undergoes further growth and causes it to deepen and invaginate inward forming the Neural Groove

Question 17

What is the Ectoderm and what does it form?

Answer 17

Outer layer
Forms skin, oral mucosa, enamel nerves

Question 18

What is the Mesoderm and what does it form?

Answer 18

Middle layer
Forms bone, cartilage, muscle, blood, dentin, cementum, pulp

Question 19

What is the Endoderm and what does it form?

Answer 19

Inner layer
forms lining of pharynx, digestive tube, lungs

Question 20

What is the Neural crest cells

Answer 20

4th type of tissue (PIA cells)
Develops from neuroectoderm
Helps form tissues of oral and dental tissues except for enamel

Question 21

What forms the somites? How many segments and what does it give rise to?

Answer 21

Mesoderm differentiates and divides at each side of the neural tube
38 paired cuboidal segments
Gives rise to most skeletal structures of the head, neck, and trunk, as well as associated muscles and dermis of skin

Question 22

What happens in 4th week?

Answer 22

• One tube is formed from oropharyngeal to cloacal membrane
• Foregut, midgut, hindgut is formed
• Continues to develop eyes, ears, nose, oral cavity, jaw
• Oropharyngeal membrane begins to disintegrate to become the stomodeum

Question 23

Fetal period?

Answer 23

Existing structures mature as embryo and enlarges to become a fetus