developmental

Question 1

what is the name of the 36 cells after all cell division from zygote

Answer 1

morula

Question 2

what makes up the late blastocyst

Answer 2

outside = trophectoderm
top, bottom = hypoblast
icm = epiblast

Question 3

explain formation of the three germ layers

Answer 3

after multiple cell divisions, the blastocyst loses its outer ring of cells and becomes an granola, then there is a primitive strike that generates the ectoderm, mesoderm and endoderm

Question 4

what is gastrulation

Answer 4

the formation of the three germ layers from the primitive streak and hensen’s node

Question 5

where are ectoderm cells end up

Answer 5

nervous system, epidermis

Question 6

where do mesoderm cells end up

Answer 6

heart, skeletal muscle, blood and bone

Question 7

where do endoderm cells end up

Answer 7

epithelia of GI and respiratory tract, pancreases, thyroid

Question 8

what are the key molecules in heart developmen

Answer 8

GATA, BMPs, Wnt inhibitors, Nsk2.5, Fgf

Question 9

in general, how does the heart develop

Answer 9

at 21 days, there Is a fusion into primitive heart tube which then differentiates into the different parts until it become a heart at 35 days

Question 10

how is miRNA involved in heart development

Answer 10

they control the expression of the differentiation factors needed for heart development

Question 11

what are the key molecules in lung development

Answer 11

Tbx5, Wnt2, Wnt2b, BMP

Question 12

describe formation of the lung

Answer 12

lung and trachea specification -> lung bud formation -> trachea formation

Question 13

how are fgf and shh involved in lung development

Answer 13

they provide communication between epithelium and mesenchyme, Shh inhibits FGF10 cluster of mesenchyme cells which then separate and two new buds form

Question 14

what are the signaling pathways in limn development

Answer 14

ZPA = zone of polarizing activity, Shh
AER = apical ectodermal ridge, Fgf

Question 15

what is the important of apoptosis during limb developmemnt

Answer 15

it allows for the formation of limbs like fingers through cell death

Question 16

what is teratology

Answer 16

study of birth defect

Question 17

what are teratogens

Answer 17

agents that produce birth defects

Question 18

what is developmental toxicollogy

Answer 18

study of environmental chemical that cause birth defects

Question 19

what is the incidence of birth defects

Answer 19

1/20 live births

15% spontaneous abortions

Question 20

what is specification

Answer 20

programming of stem cells to develop along a particular pathway

Question 21

what is differentiation

Answer 21

process by which an unspecialized cell matures to possess distinct function

Question 22

what are the three types of stem cell specification

Answer 22

autonomous specification
syncytial specifiation
conditional specification

Question 23

explain autonomous specification

Answer 23

cells develop along a particular pathway in the absence of any external influences

Question 24

explain syncytial specification

Answer 24

nucleus divides but cytoplasm does not

Question 25

explain conditional specification

Answer 25

fate of cell depends on condition (environment)

Question 26

what are the mechanisms of induction

Answer 26

indirect: diffusion of paracrine factors from one cell to another, matrix exchange
direct: contact between an inducing cell and responding cell

Question 27

gradient of sonic hedgehog during limb development

Answer 27

the gradient is important in proper formation, additional polarizing region causes extra limbs while small number creates grafted anterior margin