Developmental Biology

Question 1

Embryology

Answer 1

The study of the development of a unicellular zygote into a multicellular organism

Question 2

Cleavage

Answer 2

A series of rapid mitotic divisions
Increase cell number without corresponding growth in cell protoplasm
Increase SA:ratio, improving gas and nutrient exchange

Question 3

Morula

Answer 3

A solid ball of embryonic cells

Question 4

Blastulation

Answer 4

Begins when the morula develops a fluid-filled cavity (blastocoel) which becomes a hallow sphere (blastula)

Question 5

Blastula

Answer 5

A hallow sphere of cells

Stage of implantation

Question 6

Ectopic pregnancy

Answer 6

The embryo implants outside the uterus

Question 7

Gastrulation

Answer 7

After 2 weeks the embryo is fully implanted in the uterus and transforms from a single cell layer blastula into a gastrula

Question 8

Gastrula

Answer 8

A 3-layered structure

Ectoderm, endoderm, mesoderm

Question 9

Ectoderm

Answer 9

Integumentary system (epidermis, hair, nails, epithelium of the nose, mouth and anal canal), lens of the eye, retina, nervous system

Question 10

Endoderm

Answer 10

Epithelial linings of the digestive and respiratory tracts (lung) and parts of the liver, pancreas, thyroid, and bladder lining

Question 11

Mesoderm

Answer 11

Musculoskeletal system, circulatory system, excretory system, gonads, connective tissue, portions of digestive and respiratory organs

Question 12

Neurulation

Answer 12

Regions of the germ layers begin to develop into a rudimentary nervous system before week 3

Question 13

Notochord

Answer 13

Rod of mesodermal cells that develops along the longitudinal axis of the embryo just under the dorsal layer of ectoderm
Inductive effect on the ectoderm causing it to bend inward and form a groove along the dorsal surface
Neural dorsal ectoderm folds on either side of the groove and fuse, forming a closed tube which gives rise to the brain and spinal cord
Once formed, it detached from the surface ectoderm

Question 14

Neural crest cells

Answer 14

Cells at the tip of each neural fold of the notochord
Migrate laterally
Give rise to components of the peripheral nervous system (sensory ganglia, autonomic ganglia, adrenal medulla, Schwann cells)

Question 15

Organogenesis

Answer 15

The body organs begin to form

The cells interact, differentiate, change physical shape, proliferate, and migrate

Question 16

Growth

Answer 16

The organs increase in size. The continual process from infancy through childhood to adulthood

Question 17

Gametogenesis

Answer 17

Eggs and sperm develop which permits reproduction to occur

Question 18

Developmental Processes

Answer 18

1. Fertilized egg
2. 2-cell stage
3. Morula
4. Blastula
5. Gastrula
6. Neurulation
7. Organogenesis
8. Growth
9. Gametogenesis

Question 19

Placenta/Umbilical cord

Answer 19

A specialized circulatory system that supplies oxygen and nutrients, and removes carbon dioxide and metabolic wastes

Question 20

Amnion

Answer 20

A thin, tough membrane containing amniotic fluid

Question 21

Amniotic fluid

Answer 21

Acts as a shock absorber of external pressure during gestation and localized pressure from uterine contractions during labour

Question 22

Chorion

Answer 22

Begins placental formation
A membrane that completely surrounds the amnion
Assists with the transfer of nutrients

Question 23

Allantois

Answer 23

Develops as an outpocketing of the gut

Blood vessels of the allantoic wall enlarge and become the umbilical vessels

Question 24

Yolk Sac

Answer 24

The site of early development of blood vessels

Becomes associated with the umbilical vessels

Question 25

First Trimester

Answer 25

Major organs begin to develop Heart beats at ~22 days Eyes, gonads, limbs, and liver start to form 5th week - 10 mm 6th week - 15 mm 7th week - cartilaginous skeleton beings to turn into bone 8th week - most organs formed, brain fairly developed 3rd month - 9 cm

Question 26

Second Trimester

Answer 26

Tremendous amount of growing & moving | 6 months - 30-36 cm

Question 27

Third Trimester

Answer 27

Continued rapid growth and further brain development 9th month - antibodies are transported by highly selective active transport from mother to fetus. Growth rate slows & fetus becomes less active

Question 28

Labour

Answer 28

A series of strong uterine contractions | 3 stages

Question 29

1st Stage of Labour

Answer 29

Cervix thins and dilates Amniotic sac ruptures Relatively mild contractions

Question 30

2nd Stage of Labour

Answer 30

Rapid contractions that result in the birth of the baby

Question 31

3rd Stage of Labour

Answer 31

Uterus contracts expelling the placenta and umbilical cord

Question 32

Congenital disorders

Answer 32

Errors occur during fetal development often because of deleterious genes or problems with the gestation environment

Question 33

Teratogens

Answer 33

Chemical and biological agents that cause congenital disorders

Question 34

Vertical transmission

Answer 34

When a mother passes on an infection directly to her developing offspring

Question 35

Epicotyl

Answer 35

Precursor of the upper stem and leaves

Question 36

Cotyledons

Answer 36

Seed leaves Dicots have 2 seed leaves Monocots have 1

Question 37

Hypocotyl

Answer 37

The lower stem and root

Question 38

Endosperm

Answer 38

Feeds the embryo | In dicots, the cotyledon absorbs the endosperm

Question 39

Seed coat

Answer 39

Develops from the outer covering of the ovule | Embryo and its seed coat together comprise the seed

Question 40

Seed dispersal

Answer 40

Fruit is formed from the ovary walls, the base of the flower, and other consolidated flower pistil components Enables the seed to be carried more frequently or effectively by air, water, or animals Seed is released from the ovary and will germinate under proper conditions of temperature, moisture, and oxygen

Question 41

Meristem cells

Answer 41

Growth in higher plants is restricted to the embryonic cells | These tissues undergo active cell reproduction

Question 42

Apical meristem

Answer 42

Found in the tips of roots and stems | Growth in length occurs only at these points

Question 43

Lateral meristem (Cambium)

Answer 43

Located between the xylem and phloem Tissue permits growth in diameter and can differentiate into new xylem and phloem cells Not an active tissue in monocots or herbaceous dicots but is predominant in woody dicots