Organ and Tissue Differentiation

Question 1

Cut edge of amnion

Answer 1

Outer membrane when looking at embryo at ‘insect’ stage

Question 2

Buccopharyngeal membrane

Answer 2

Ectoderm and endoderm are in direct contact with each other forming a thin membrane
Forms septum between primitive mouth and pharynx

Question 3

Neural plate

Answer 3

Derived from ectoderm
Serves as basis for nervous system
Opposite primitive streak

Question 4

Somites

Answer 4

Bilaterally paired blocks of paraxial mesoderm that form along the head/tail axis is segmented animals
Each somite has 4 areas

Question 5

Neural fold

Answer 5

Folds on each side of neural plate

During neurulation the folds will fuse with the fold on the opposite side of the embryo and give rise to the neural tube

Question 6

Neural groove

Answer 6

Shallow groove between neural folds on neural plate

Question 7

Cloacal membrane

Answer 7

Ectoderm and endoderm are in direct contact with each other

Forms openings of anus, urinary tract and reproductive tract

Question 8

Neural ectoderm

Answer 8

Forms nervous system structures (neural tube on inside)

Question 9

Non-neural ectoderm

Answer 9

Forms epidermis (outside)

Question 10

Neural tube

Answer 10

Hollow structure formed by several layers of ectodermal cells called neural crest

Question 11

Notochord

Answer 11

Axial mesoderm
Formed by mesodermal cells migrating from primitive node towards head end to make hollow tube of cells
This hollow tube eventually becomes solid cylinder called notochord

Question 12

Neural crest

Answer 12

Formed from neural folds fusing together to make the neural tube
Some ectodermal cells from neural tube form several layers of cells called neural crest

Question 13

4 sections of somite

Answer 13

Dermatome - dorsal
Myotome - dorsal
Syndetome - ventral
Sclerotome - ventral

Question 14

Dermatome

Answer 14

Dorsal
Gives rise to dermis
Contribute to skin, fat and connective tissue in neck and trunk

Question 15

Myotome

Answer 15

Dorsal

Forms muscles

Question 16

Syndetome

Answer 16

Ventral

Tendon progenitor cells

Question 17

Sclerotome

Answer 17

Ventral

Forms vertebrae and ribs

Question 18

Induction

Answer 18

A tissue stimulates the development and specialisation of an adjacent unspecialised tissue by producing chemical substance to influence responding tissue

Question 19

Ectoderm/endoderm contact membranes

Answer 19

Buccopharyngeal (oropharyngeal) - connects mouth to pharynx and GI tract in week 4
Cloacal - forms openings of anus, urinary tract and reproductive tract in week 7

Question 20

Notochord induction

Answer 20

Induces mesoderm cells to develop into vertebral bodies

Forms nucleus pulposus of invertebral discs

Question 21

Allantois

Answer 21

Sac that helps with gas exchange and liquid waste
Formed by caudal wall of the yolk sac
Small and vascularised

Question 22

Neurulation

Answer 22

1) Notochord induces ectodermal cells to form neural plate
2) Edges of neural plate become elevated and form neural folds
3) Neural folds come together and fuse to form neural tube
4) Some neural tube cells form several layers called the neural crest
5) Head end of neural tube forms 3 enlarged areas called primary brain vesicles

Question 23

Primary brain vesicles

Answer 23

Prosencephalon - forebrain
Mesencephalon - midbrain
Rhombencephalon - hindbrain

Question 24

Prosencephalon secondary vesicles

Answer 24

Telencephalon

Diencephalon

Question 25

Rhombencephalon secondary vesicles

Answer 25

Metencephalon | Myelenchephalon

Question 26

Organisers

Answer 26

Choreograph differentiation and signals by secreting morphogens Tail organiser formed by primitive node Head organiser formed by AVE

Question 27

Morphogens

Answer 27

Secreted by organisers Bind to cell receptors Concentration dependent Exposure to morphogen decides cell function

Question 28

HOX genes

Answer 28

Expressed in all 3 layers but in different concentrations and of different types Variation decides cell differentiation Controls body plan of embryo along rostral/caudal axis Determines body structure that will develop on a segment

Question 29

Somitogenesis

Answer 29

Forms somitomeres Mesoderm adjacent to notochord and neural tube forms paired longitudinal columns of paraxial mesoderm Paraxial mesoderm forms somite pairs

Question 30

Telencephalon brain parts

Answer 30

Cerebral cortex | Basal ganglia

Question 31

Mesencephalon brain parts

Answer 31

Tectum | Cerebral penducle

Question 32

Metencephalon brain parts

Answer 32

Pons | Cerebellum

Question 33

Diencephalon brain parts

Answer 33

Thalamus, hypothalamus

Question 34

Myelencephalon brain parts

Answer 34

Medulla

Question 35

Pharyngeal arches

Answer 35

Series of outpouches on the developing pharynx which give rise to many structures in the embryo Ectoderm on outside, mesoderm in middle, endoderm on inside

Question 36

Aortic arches

Answer 36

Vascular structures that give rise to the great arteries of the neck and head Formed sequentially within the pharyngeal arches

Question 37

Pharyngeal arch 1

Answer 37

Mastication Jaw cartilage Mandible and maxilla From ectodermal neural crest

Question 38

Trigeminal ganglion

Answer 38

Sensory nerve cell cluster of the trigeminal nerve

Question 39

Trigeminal nerve

Answer 39

Nerve responsible for sensation in the face and motor control such as chewing and biting

Question 40

Failure to close rostral neuropore

Answer 40

Fatal anencephaly

Question 41

Failure to close caudal neuropore

Answer 41

Spina bifida

Question 42

Neural crest cells

Answer 42

Give rise to PNS at spinal cord by producing sensory and gut neurons Produce adrenal cells and melanocytes Give rise to cartilage, bones and muscles at head

Question 43

Transverse folding

Answer 43

Folding along transverse axis of embryo Head and tail move down Endoderm moves towards middle Tubes with blind ends form to become the gut Lateral edges move down and meet along the middle Embryo has been transformed into a tube

Question 44

Longitudinal bending

Answer 44

Flat disc of trilaminar embryo bends along rostral/caudal axis Transformed into inverted C shape

Question 45

Heart development

Answer 45

Cells that give rise to heart are found as two patches near rostral end of primitive streak Primitive ventricle Primitive atrium Bulbis cordis and sinus venous

Question 46

Heart looping

Answer 46

Tube folds so primitive ventricle moves towards tail and primitive atrium moves towards head

Question 47

Primitive atrium

Answer 47

Left and right atrium

Question 48

Primitive ventricle

Answer 48

Left and right ventricle

Question 49

3 circuits for embryonic circulation

Answer 49

Intra-embryonic circuit for embryo tissues Vitelline circuit for nutrient gathering Allantois for nitrogenous waste

Question 50

Describe the path of blood circulation

Answer 50

``` Dorsal aorta Aortic arches Embryo Vitelline arteries Yolk sac Umbilical vein Embryo Umbilical artery Placenta ```

Question 51

Components in intra-embryonic circulation

Answer 51

Anterior cardinal vein Dorsal aorta Aortic arches Posterior cardinal vein

Question 52

Components in vitelline circulation

Answer 52

Vitelline vein Vitelline artery Vitelline capillaries

Question 53

Components in placental circulation

Answer 53

Placental capillaries Umbilical artery Umbilical vein

Question 54

Placenta formation

Answer 54

From chorion and decidua basalis

Question 55

Components of circulatory system that are poorly oxygenated

Answer 55

Anterior cardinal vein Posterior cardinal vein Vitelline vein Vitelline capillaries

Question 56

Components of circulatory system that are well oxygenated

Answer 56

Umbilical vein

Question 57

Components of circulatory system that have mixed oxygenation

Answer 57

``` Dorsal aorta Heart Aortic arches Umbilical artery Vitelline artery Placental capillaries ```