Human Development #4

Question 1

Summarize what occurs in week 4 of development.

Answer 1

Organization of mesoderm and body folding to create 3-d body plan

Question 2

What are the 2 types of tissue that can make up the mesoderm?

Answer 2

May be epithelial or mesenchymal

Question 3

What are the regional groupings of mesoderm?

Answer 3

Paraxial mesoderm, intermediate mesoderm, lateral plate mesoderm

Question 4

Describe the locational development of mesoderm regional groupings

Answer 4

Cephalo-caudal development (begins at cranial end)

Question 5

What is initial step involving paraxial mesoderm in mesoderm development

Answer 5

Paraxisal mesoderm begins forming segmentations.

Question 6

Somitomeres → cephalic somitomeres

Answer 6

Partially segmented structures formed at cranial end of paraxiae mesoderms

Question 7

What does the more caudal paraxial mesoderm form after completely segmenting?

Answer 7

Occipital somites

Question 8

What is the most caudal structure to form from paraxial mesoderm?

Answer 8

Trunk somites, caudal to occipital somites

Question 9

How many cephalic somitomeres form?

Answer 9

7

Question 10

How many somites (occipital + trunk) form?

Answer 10

42-44

Question 11

_____ stimulate the formations of spinal nerves?

Answer 11

Somites

Question 12

Somites disperse to form _____ and _______

Answer 12

Sclerotomes and dermamyotomes

Question 13

Sclerotome

Answer 13

Form axial skeleton

Question 14

Myotome

Answer 14

Forms skeletal muscle

Question 15

Dermatome

Answer 15

Forms endothelial cells of vessels + dermis

Question 16

Dermateme

Answer 16

Forms endothelial cells of vessels + dermis

Question 17

Syndetome

Answer 17

Tendon precursor cells

Question 18

Sclerotome

Answer 18

Bone and cartilage

Question 19

What does the intermediate mesoderm form?

Answer 19

Parts of the urogenital system

Question 20

Describe the organization of the lateral plate mesoderm

Answer 20

Splits into somatic and splanchnic mesoderm layers; resulting space is the embryonic coelom

Question 21

What forms from the embryonic coelom?

Answer 21

Future adult body cavities

Question 22

What forms on the ecotderm aspect of the lateral plate mesoderm?

Answer 22

Somatic Lateral plate mesoderm

Question 23

Somatic lateral plate mesoderm

Answer 23

with ectoderm forms somatopleure, with will become the outer body wall

Question 24

What forms from the endoderm of the lateral plat mesoderm?

Answer 24

Splanchnic Mesoderm

Question 25

Splanchnic Mesoderm

Answer 25

with endoderm forms splanchnopleure which will become visceral wall

Question 26

Somatopleure

Answer 26

somatic mesoderm +ectoderm = outer body wall

Question 27

splanchnopleure

Answer 27

splanchnic mesoderm + endoderm = visceral wall

Question 28

embryonic coelom

Answer 28

formed by splitting of lateral plat mesoderm; U-shaped

Question 29

What is the embryonic coelom continuous with?

Answer 29

With the extaembryonic coelom/chorionic cavity

Question 30

induction

Answer 30

process whereby one group of cells determines the development of another group of cells (ex: hensen's node in formation of secondary body axis)

Question 31

body folding

Answer 31

transforms the trilaminar embryonic disk into a tub within a tube during week 4 of edevelopment

Question 32

median folds

Answer 32

head to tail folds

Question 33

head fold

Answer 33

cardiogenic region and oropharyngeal membrane swing ventrally and caudally

Question 34

tail fold

Answer 34

cloacal membrane swings ventrally and cranially, in which part of yolk sac is incorporated into embryo as primitive gut tube

Question 35

What forms the primitive gut tube

Answer 35

portion of the yolk sac that is incorporated

Question 36

horizontal folding

Answer 36

lateral folds - lateral plate mesoderms move ventrally and medially -splanchnic LP mesoderm surrounds the primitive gut tube -somatic lop mesoderm participates in outer body wall formation

Question 37

What establishes the primary body axis?

Answer 37

primitive node and notochord

Question 38

What may set up left-right axis?

Answer 38

beating of cilia

Question 39

situs inversus

Answer 39

clinical condition where left-right axis is partially of completely reversed. Approximately 20% of cases have abnormal cilia function

Question 40

holoprosencephaly

Answer 40

failure of development of 2 hemispheres (single brain ventricle, cyclopia) - defect in 3rd week of development. OH consumption or genetic defect in SHH gene?

Question 41

sirenomelia

Answer 41

Insufficient mesoderm development in caudal region - problem in gastrulation. Effects all caudal mesoderm derived structures