FORM & FUNCTION (Neurulation, Coelomic Cavities, etc.)

Question 1

Pear-shaped gastrula:

Answer 1

-continues to change where the three germ layers and the associated structures undergoes various changes
>assisted by gene regulatory networks and cellular processes

Question 2

Cellular processes:

Answer 2

-cell proliferation
-migration/movement of cells
-formation of tubes and spaces within the embryo

Question 3

Ectoderm gives rise to:

Answer 3

-neuroectoderm
-surface ectoderm

Question 4

Mesoderm transforms into:

Answer 4

-paraxial mesoderm
-intermediate mesoderm
-lateral plate mesoderm

Question 5

Endoderm develops into:

Answer 5

-gut tube
-respiratory tract

Question 6

Formation of the primitive streak to neurulation:

Answer 6

1. Ectoderm proliferates to form the neural plate/neuroectoderm
2. Neural plate to neural grove
3. Neural grove to neural tube: gives rise to brain and spinal cord
4. Induction leads to thickening of the surface ectoderm cells to form placodes

Question 7

Neural tube gives rise to:

Answer 7

-brain
-spinal cord

Question 8

Peripheral NS comes from:

Answer 8

-neural tubes
-neural crest cells: migrated neuroectoderm cells)

Question 9

Placodes give rise to:

Answer 9

-nasal chambers
-lens of eye
-inner ear
-cranial nerves
-etc.

Question 10

Neurulation: example of roles of genes

Answer 10

-dorsal ventral patterning of neural tube requires 2 primary signaling centers
1. Surface ectodermal cells
2. Notochord

Question 11

Surface ectodermal cells:

Answer 11

-secrete bone morphogenetic protein (BMP) 4 and 7 so some ectodermal cells become roof plate of tube

Question 12

Notochord:

Answer 12

-sonic hedgehog (Shh) signaling from notochord produces floor plate of tube

Question 13

Neurulation:

Answer 13

-folding of the neural plate into the neural tube
-embryo at this stage=neurula

Question 14

Mesoderm types:

Answer 14

-paraxial
-intermediate
-lateral
*all connective tissue components are mesodermal in origin

Question 15

Paraxial mesoderm:

Answer 15

-gives rise to aggregation of cells:
>somitomeres near the neural plate (head region)
>somites in caudal region

Question 16

Somitomeres:

Answer 16

-gives rise to structures in the head region

Question 17

Somites:

Answer 17

-form the axial skeleton

Question 18

Intermediate mesoderm:

Answer 18

-forms the reproductive and urinary systems

Question 19

Lateral mesoderm:

Answer 19

-clefts: spaces that appear and fuse together and creates a cavity=intra-embryonic coelom
-forms the somatopleure (somatic mesoderm and ectodermal cells) and splanchnopleure (splanchnic mesoderm and endoderm cells)
>eventually line the space in between (later turn into body cavities): mesodermal lining=mesothelium

Question 20

Mesothelium:

Answer 20

-simple squamous epithelial cells
-forms the serous membranes that line the body cavities (pluera, peritonium, pericardium)

Question 21

Endoderm gives rise to:

Answer 21

-epithelium of the gut and respiratory tract and their glands
-urinary bladder
-middle ear and auditory tube
-liver
-pancreas
-thyroid and parathyroid glands

Question 22

Process of formation: coelomic cavities:

Answer 22

-cleft develops within the right and left lateral mesoderm
-cleft later coalesce, forming a cavity that splits the lateral mesoderm into an outer layer of somatic mesoderm and an inner layer of splanchnic mesoderm
*cavities between the 2 layers of mesoderm on L and R sides are called the COELOMIC cavities
*lateral folding of coelomic cavities give rise to pericardial, pleural and peritoneal cavities

Question 23

Pleural-pericardial cavity:

Answer 23

-first formation of pleural and pericardial cavities
-covers the embryonic/developing lungs and heart
*further development and folding of mesoderm leads to the formation of pleural and pericardial cavities (pericardial fold)

Question 24

Pleural and pericardial cavities:

Answer 24

-both lined by mesothelium
-mediastinum
-all these structures are found within the thoracic cavity

Question 25

Mediastinum:

Answer 25

-mesenchymal tissue that forms a septum separating the pleural cavities

Question 26

Function of pleural and pericardial cavities:

Answer 26

-protect the lungs (pleura) and the heart (pericardium)

Question 27

Diaphragm arises by the fusion of 3 embryonic structures:

Answer 27

-pleuroperitoneal folds
-mesothelial folds
-septum transversum (aggregation of mesoderm)

Question 28

Mesodermal structures: diaphragm

Answer 28

-develop into the muscular structure of the diaphragm

Question 29

Diaphragm:

Answer 29

-allows structures (ex. blood vessels, nerves) to pass through at three different sites of the diaphragm

Question 30

Improper formation of diaphragm:

Answer 30

-cause developmental defects

Question 31

Function of diaphragm:

Answer 31

-structural partition of the thoracic and abdominal cavities

Question 32

Peritoneal cavity/peritonium:

Answer 32

-mesothelium lining the abdominal cavity
-intra- and retro-peritoneal
-omentum

Question 33

Intra-peritoneal:

Answer 33

-organs enclosed by a fold of the peritoneum

Question 34

Retro-peritoneal:

Answer 34

-organs partly covered by peritoneum

Question 35

Omentum:

Answer 35

-fold of the peritoneum that attaches an organ to the stomach