Lecture 1 - embryogenesis

Question 1

What does BMP stand for and where are they expressed?

Answer 1

Bone morphogenic proteins - normally expressed in ECTODERM

Question 2

How are BMPs involved in neural induction?

Answer 2

BLOCKADE of BMP signalling induces the formation of the NEURAL PLATE

Question 3

Explain the role of the notochord in neural induction

Answer 3

The notochord has important inductve capacity and was found to contain BMPS

Question 4

Outline some derivatives of the neural crest cells

Answer 4

Sensory neurons, autonomic ganglia, Schwann cells etc.

Question 5

Outline the establishment of the neuraxis

Answer 5

notochord will release BMP INHIBITORS (e.g. noggin) effecting the ROSTRAL neural plate

Somites produce posteriorising agents (e.g. Retinoic acid) effecting the CAUDAL neural plate

Question 6

Further subdivision of the neuraxis

Answer 6

Subdivision occurs and we have the formation of segments called neuromeres (early divisions of spinal cord segments)

Question 7

Rhombomeres

Answer 7

The developing hindbrain has 8rs
* Motor neurons emerge from even-numbered rs
* Cell bodies also come from he r below

Question 8

Specification of Rhombomeres

Answer 8

There is a gradient of RA (more in caudal)
* Induces expression of HOX genes

Question 9

Retinoic Acid (RA)

Answer 9

Biologically active derivative of Vit A
* expressed in somites along spinal cord and caudal hindbrain
* HOX family is major target

Question 10

Ventral signalling

Answer 10

1. Shh released by notochord (highest dose @ midline)
2. Shh induces formation of Floor Plate Cells (FPCS @ ventral midline)
3. induce formation of MN precursors
4. MN precursors > MN > extend axons towards targets

Question 11

Various influences of ventral signals on spinal cord patterning

Answer 11

1. Normal > MN in ventral
2. 2nd Notochord > extra pool of MN more dorsally
3. Lack of FPCs and MNs in absence of notochord

Question 12

Dorsal signalling

Answer 12

1. BMPs induce Roof Plate Cells (RPCs @ dorsal midline)
2. BMP signalling induces Neural Crest Cells (NCCs) to differentiate into DRG and sensory interneuron precursors.

Question 13

What are Morphogens and what are some examples?

Answer 13

Shh, BMPs, FGFs, RA
* Diffusible factors which act in concentration-dependent manner to activate or repress TFs

Question 14

Outline some genes encoding transcription factors

Answer 14

RA receptors, Hox genes
* Control expression of other genes

Question 15

Outline some genes encoding cell-surface or secreted signalling molecules

Answer 15

Eph receptors and the ephrins; neurotrophins
* Key role in brain development by directly regulating interactions between cells

Question 16

Flexures in the 3 vesicle stage

Answer 16

1. Cephalic
2. Cervical

Question 17

Flexures in the 5 vesicle stage

Answer 17

1. Cephalic
2. Cervical
3. Pontine (4th ventricle is mediated by this bend)

Question 18

Name the three components of the neural tube at the 3 vesicle stage:

Answer 18

1. PROsencephalon (FOREbrain)
2. MESencephalon (MIDbrain)
3. RHOMbencephalon (HINDbrain)

Question 19

What does the Prosencephalon differentiate to in the 5 vesicle stage?

Answer 19

1. TELEncephalon
   * Cerebral Cx. Amygdala, Hippocampus, Striatum, Olf. Bulb
   * associated with the LATERAL ventricle
2. DIEncephalon
   * Thalamus, Hypo/Epi/Subthalamus, Retina
   * associated with the 3RD ventricle

Question 20

What is important about the Mesencephalon as development continues?

Answer 20

Does not differentiate and goes on to become the MIDbrain
* It is associated with the Cerebral Aq

Question 21

What does the Rhombencephalon differentiate to in the 5 vesicle stage?

Answer 21

1. METencephalon
   * Pons + Cerebellum
2. MYlencephalon
   * Medulla
   Both associated with 4TH ventricle