L9 - Development of the Senses

Question 1

Where (3) can the sensory organs originate from

Answer 1

Neural crest - sensory neurones of the DRG
Neural tube - e.g. retina
Placodes

Question 2

Descibe how the eye forms

Answer 2

As the optic vesicles grow out they touch the adjacent surface ectoderm - this induces a thickening in the ectoderm - optic placode
Placode will then form the lens
Optic vesicle will form a double layered cup

Question 3

What is different about the two layers of the optic cup

Answer 3

They will differentiate differently

Question 4

How does the outer layer of the double layered optic cup differentiate

Answer 4

Retinal pigment epithelium that produce melanin

Question 5

How does the inner layer of the double layered optic cup differentiate

Answer 5

Cont a stem like population which can either self renew or differentiate via progenitors INTO
Diverse ganglion cells
Interneurones
Light sensitive photo receptor cells in the neural retina

Question 6

What are the master transcription factors of the eye

Answer 6

Pax6

Question 7

What is Pax6

Answer 7

Ectopic activator - ectopic eye development

Question 8

Neurones of the eye are built in a similar way to …

Answer 8

Neurones in the spinal chord

Question 9

What are the three zones of the eye

Answer 9

Layer 1 (closest layer to the RPE cells)
Neuroblasts in this region form RODs and CONES 

Layer 2 (in the middle)
Neuroblasts in this region form bipolar neurones 

Layer 3 (closest to the front of the eye)
Neuroblasts in this region form Ganglion cells

Question 10

What determine which type of neurone a cell will become

Answer 10

Time that the neurone is born

Question 11

Describe the connections of the eye

Answer 11

Optic nerve –> Ganglion cells –> Bipolar neurones –> Rods and Cones

Question 12

What gene is required for developement of the eye

Answer 12

Pax6 gene

Question 13

Where do the placodes originate from

Answer 13

Similar to sensory neurone origins (e.g. the DRG)

Question 14

What is the top end of the neural plate border crucial for

Answer 14

Head placodes

Question 15

What is the lower end of the neural plate border crucial form

Answer 15

Neural crest formation

Question 16

What are the 8 cranial placodes

Answer 16

Olfactory 
Lens 
Trigeminal 
Geniculate 
Epibranchial 
Petrosal 
Otic 
Nodose

Question 17

Describe the developement of the otic placode

Answer 17

Ear is derived from the otic placode
Folds to give pits which then pinch off to form vesicles
Neurogenic regions are at the base of the vesicle
Sensory components then come from this