Embryology

Question 1

name the four regions of the mesoderm

Answer 1

notochord
paraxial
intermediate
lateral plate

Question 2

the notochord of the mesoderm forms what?

Answer 2

nucleus pulposus of the IV discs

Question 3

the paraxial mesoderm forms what?

Answer 3

vertebrae, ribs, muscles and skin of limbs and trunk

Question 4

the lateral plate mesoderm forms what?

Answer 4

limb skeleton

Question 5

how does paraxial mesoderm start to form the muscle and skin of body?

Answer 5

by forming somites

Question 6

the paraxial mesoderm divides into three components…name them

Answer 6

sclerotome (bone/cartilage
myotome (muscle
dermatome (skin

Question 7

the lateral plate mesoderm forms divides into two layers name them

Answer 7

splanchnic and somatic layer

Question 8

what does the somatic layer of the lateral plate mesoderm form

Answer 8

limb skeleton

Question 9

name the two types of bone formation

Answer 9

intramembranous ossification and endochondral ossification

Question 10

what cells start intramembranous ossification? what do they become?

Answer 10

mesenchymal cells become osteoblasts that make a bone matrix

Question 11

what bones are made via intramembranous ossification?

Answer 11

flat bones of the skull

Question 12

what is the first step in endochondral ossification?

Answer 12

hyaline cartilage model develops

Question 13

what is the second step in endochondral ossification?

Answer 13

bone collar forms around the cartilage diaphysis and chondrocytes die

Question 14

what is the third step in endochondral ossification?

Answer 14

blood vessels and osteoblasts invade and make a primary ossification center in the diaphysis and bone formation spreads

Question 15

what is the fourth step in endochondral ossification?

Answer 15

secondary ossification centers form in the epihphyses

Question 16

what are the two locations that cartilage doesnt die right away in endochondral ossification?

Answer 16

articular cartilages

epiphyseal plates

Question 17

when do we have all four limb buds?

Answer 17

4 weeks

Question 18

upper limb is from what somites?

Answer 18

C5-T1

Question 19

lower limb is from what somites?

Answer 19

L2-S2

Question 20

what is the hormone that initiates growth of the limb bud>

Answer 20

fibroblast growth factor

Question 21

what cells produce fibroblast growth factor? what does this mean for limb growth?

Answer 21

apical ectodermal ridge cells…means limbs grow at distal end

Question 22

what week do we cartilage model of all limb bones?

Answer 22

week 8

Question 23

describe how digits form

Answer 23

develop digital rays then you get apoptosis to separate

Question 24

what is it called when you have connected digits

Answer 24

syndactyly

Question 25

what is achondroplasia? mutation? inheritance?

Answer 25

type of dwarfism…AD fibroblast growth factor receptor mutation

Question 26

how does achondroplasia look?

Answer 26

regular size trunk and head with small limbs

Question 27

name three limb muscles that commonly have agenesis or partial development

Answer 27

palmaris longus
peck major
serratus anterior

Question 28

what cells lead to the vertebrae?

Answer 28

sclerotome cells

Question 29

what cells lead to the ribs?

Answer 29

sclerotome cells

Question 30

what type of ossification leads to vertebrae?

Answer 30

endochondral

Question 31

explain how spinal nerves grow and how it works with vertebrae?

Answer 31

they grow out and will actually break up the developing vertebra that is adjacent and the new vertebrae forms from a caudal and cranial portion of the two closest vertebrae

Question 32

what is hemivertebrae? what can it lead to?

Answer 32

lack of formation of part of vertebrae…scoliosis

Question 33

what can not form that leads to mild/moderate forms of spina bifida?

Answer 33

dorsal vertebral arch

Question 34

what tissue are skull bones from?

Answer 34

mesoderm