All of Geoff's Lecture

Question 1

What are critical periods?

Answer 1

periods of time where the foetus can be negatively affected by internal and/or external factors

Question 2

What critical periods occur earliest?

Answer 2

More critical systems develop earlier so have the potential to be affected earliest and for longer than other parts of the foetus

Question 3

Critical periods earliest to latest

Answer 3

Neural
Heart
Upper limbs
Lower limbs
Ear
Eye
Palate
Teeth
External genitalia

Question 4

What are carcinogens?

Answer 4

Agents or factors that initiate or induce neoplasia/carcinogenesis

Question 5

What are mutagens?

Answer 5

agents or factors that produce a change in the genetic code of an organism

Question 6

What are teratogens?

Answer 6

agents or factors that cause the development of physical defects in the embryo or foetus

Question 7

Teratogenic effects during early embryogenesis:

Answer 7

effects on DNA, mutations at a genomic or chromosomal level

Question 8

Teratogenic effects during mid embryogenesis/early foetal:

Answer 8

effects on cell proliferation, differentiation or cell death

Question 9

Teratogenic effects during late foetal:

Answer 9

only highly proliferating tissues still susceptible

Question 10

How does the inner cell mass form?

Answer 10

Cell division creates morula
Cleavage division of cells - no growth so reduces in size
Cavitation occurs due to sodium being pumped actively into central area
Osmotic pressure causes the cavity within the blastocyst to expand and form blastocoel

Question 11

Embryonic disc formation

Answer 11

Further fluid and cellular migration creates disc from the ICM which is a flattened pear shape
Disc initially bilaminar but becomes trilaminar

Question 12

What are the two layers of the bilaminar disc

Answer 12

Epiblast - superficial layer - embryonic body
Hypoblast - deep cell layer forms extraembryonic membranes, cells delaminate from second layer, blastocoel now covered by two layers

Question 13

What are the three primary germ layers?

Answer 13

Ectoderm, mesoderm, endoderm

Question 14

What is the process that turns the bilaminar into a trilaminar disc?

Answer 14

Gastrulation

Question 15

Ectoderm makes:

Answer 15

epidermis of the skin, hair, lining of the mouth and nose, glands of the skin, nervous system

Question 16

Mesoderm makes:

Answer 16

dermis of the skin, muscle, skeleton, circulatory system, gonads, kidneys, outer layers of the digestive and respiratory tracts

Question 17

Endoderm makes:

Answer 17

lining of the digestive and respiratory tracts, liver, pancreas

Question 18

Central implantation

Answer 18

blastocyst remains within uterine lumen

Question 19

Eccentric implantation

Answer 19

blastocyst lies within uterine crypt or recess

Question 20

Interstitial implantation

Answer 20

conceptus invades the uterine wall

Question 21

Maternal placenta

Answer 21

endometrial lining of uterus

Question 22

Foetal placenta

Answer 22

chorion and yolk sac - transitory placenta
chorion and allantois - definitive placenta

Question 23

Choriovitelline placenta

Answer 23

Chorion and yolk sac, vitalline vessels, precedes development of chorioallantoic placenta

Question 24

Chorioallantoic placenta

Answer 24

chorion and allantois, allantoic vessels - umbillical vessels, definitive

Question 25

Deciduate parturition

Answer 25

Invasion and destruction of maternal tissue results in shedding of maternal tissue

Question 26

Non-deciduate parturition

Answer 26

Virtually no loss of maternal tissue at parturition

Question 27

Anterior polarisation

Answer 27

AVE - anterior visceral endoderm

Question 28

Posterior polarisation

Answer 28

Node

Question 29

Left side in chick embryo

Question 30

Right side in chick embryo

Question 31

Left-right asymmetry

Question 32

Timing of separation of monozygotic twins

Answer 32

Pre-blastocyst - two chorions, two amnions Early blastocyst - one chorion, two amnions Late blastocyst - one chorion, one amnion

Question 33

Define stem cell

Answer 33

A cell that can produce identical copies of itself indefinitely

Question 34

Stages stem cells go through

Answer 34

Totipotent - can create any cell Pluripotent - can create any cell excluding embryonic support Progenitor - Is committed to become a mesoderm, endoderm or ectoderm

Question 35

What are somites?

Answer 35

cells derived from condensation of paraxial mesoderm

Question 36

4 types of somite

Answer 36

Sclerotome - vertebrae and rib cartilage Myotome - musculature of back ribs and limbs Dermatome - dermis of the back Syndetome - tendons and blood vessels

Question 37

Epithelialisation of somites

Answer 37

fibronectin and N-cadherein organises inner mesenchymal and epithelial components

Question 38

What are myoblasts?

Answer 38

Muscle precursor cells

Question 39

Primaxial myoblasts

Answer 39

Closest to neural tube Will form the primaxial muscles Include the intercostal muscles and deep muscles of the back

Question 40

Abaxial myoblasts

Answer 40

Further from the neural tube Will form the abaxial muscles Include body body, limbs and tongue

Question 41

Future satellite cells

Answer 41

Arise from central myotome Remain undifferentiated Postnatal muscle growth and repair

Question 42

Hox gene code

Answer 42

encode transcription factors providing cranial-caudal axis

Question 43

Step 1 of muscle generation

Answer 43

Myotome cells are specified to become myoblasts by induction of MyoD Primaxial myotome - Pax3 Medial myotome - Myf5

Question 44

Step 2 of muscle generation

Answer 44

Myoblast numbers are expanded under the influence of FGFs

Question 45

Step 3 of muscle generation

Answer 45

Cell adhesion molecules control muscle cell alignment

Question 46

Step 4 of muscle generation

Answer 46

Myoblasts begin to fuse together to create myotubes, this occurs as myoblasts exit the cell cycle due to depletion of fibroblast growth factors

Question 47

Step 5 of muscle generation

Answer 47

Myotubes complete fusion and coordinated contraction can be initiated