Early Embryonic Development

Question 1

teratogen

Answer 1

any agent, or factor that can cause congenital anomalies in an embryo or fetus

Question 2

multipotent

Answer 2

can develop into more than one cell type

more limited than pluripotent cells

adult stem cells

Question 3

totipotent

Answer 3

can form all the cell types in a body, plus the placental cells

Embryonic cells within the first couple of cell divisions after fertilization are the only ones

Question 4

pluripotent

Answer 4

can give rise to all of the cell types that make up the body

embryonic stem cells

Question 5

unipotent

Answer 5

one stem cell has the capacity to differentiate into only one cell type

Question 6

What is migration?

Why is it important?

Answer 6

movement of cells in particular directions to specific locations

development and maintenance of organism

• embryonic tissue formation
• wound healing
• immune responses

Question 7

differentiation

Answer 7

unspecialized embryonic cell acquires features of a specialized cell i.e. heart, liver, or muscle cell

Question 8

Characteristics of mesenchymal tissue.

Develops into…

Answer 8

lack of polarity causes loosely associated cells creating a large extracellular matrix

Develops into connective, lymphatic and circulatory tissue

Question 9

What are the teratogenic influences on the 3 stages of development

Answer 9

Predifferentiation - Death of embryo

Organogenesis - Structural defects (embryonic period)

Fetal growth - Affects functional maturation

Question 10

What is a zygote?

Where does it divide?

What are the resulting cells called?

Answer 10

fertilized egg cell

Divisions (cleavage) occur in uterine tube

resulting cells are called blastomeres

Question 11

Morula

Answer 11

16 cells, ‘mulberry’

late morula has 32 cells

zona pellucida still intact

Question 12

What are the two parts of the blastocyst, and what do they end up forming?

Answer 12

outer cell mass (trophoblast) - will form part of placental membranes

inner cell mass (embryoblast) - will form entire embryo
through a bilaminar disc of epiblast and hypoblast

zona pellucida is shed shortly

Question 13

What is gastrulation?

Answer 13

single-layered blastula turns into trilaminar (“three-layered”) gastrula

Question 14

primitive streak

Answer 14

invagination in epiblast layer

will establish bilateral symmetry and initiate germ layer formation

Question 15

notocord

Answer 15

Signaling structure for neural tube formation

formed from group of cells migrating through primitive node and down midline ventral epiblast

Question 16

neuralization

Answer 16

notochord signals the ectoderm to form the neural plate

neural plate folds to form the neural tube, which will eventually form the CNS

Question 17

somite

Answer 17

part of paraxial mesoderm that gives rise to the vertebrae of the spine, rib cage, skeletal muscle, cartilage, tendons, and skin

Question 18

What does the somite give rise to?

Answer 18

dermatomes

myotomes - skeletal muscle

sclerotomes - tendons, cartilage and bone

Question 19

Ectoderm - precursor for…

Answer 19

epidermal structures (skin)

lining of oral & nasal cavity, and anus

nervous system

Question 20

Mesoderm - precursor for…

Answer 20

M - Muscle tissue

E - Endothelium and Mesothelium

S - Connective tissues & Cardiovascular system

O - Urogenital tract

Question 21

Endoderm - precursor for…

Answer 21

E - Epithelial structures:

N - Lining & glands of

D - Digestive and

O - (O₂) - Respiratory systems