1. Tues March 20, 2012 Diane Lagace, PhD CMM/BIO4350
Assistant Professor Department of Cellular and Molecular Medicine (CMM) Neuroscience Program RGH, Room 3510G, University of Ottawa,

2. 7 Lectures Embryonic Development 101 Gross Neuroantaomy
Chapter 7: Understanding CNS structure through development (p )
Gross Neuroantaomy
Chapter 7: Gross Organization of Mammalian Nervous System (p )
Chapter 7 Appendix: Illustrated Guide to Human Neuroanatomy (p )
The Genesis of the Neuron (Neurogenesis) and Neuronal Connections
Chapter 23: The Genesis of Neuron, Connections and Elimination of Cells and Synapses (p )
Regeneration of the Nervous System
From lecture notes only; not in text book
Chemical Controls of Brain and Behavior
Chapter 15: Hypothalamus, ANS, Neurotransmitter Systems (p )
Motivation and Homeostasis
Chapter 16: Feeding Regulation Short and Long-Term and Why We Eat (p )
Sex and the Brain
Chapter 17 (p )

3. What Do I Need to Know?
Text book Notes Both

4. Outline Lecture #1 Gastrulation
Formation of 3 germ layers (not in text book)
Neurulation:
Formation of neural tube (p )
3. Differentiation and Formation of the Major Subdivision of the Brain
Forebrain, Midbrain, Hindbrain (p )
4. Differentiation of the Spinal Cord (p )
The Cerebral Cortex (p ) Thursday

5. How Does the Brain and Spinal Cord Develop?

6. Video http://www.youtube.com/watch?v=UgT5rUQ9EmQ Human Development

7. Inner Cell Mass Forms 2 Layer: Epiblast and Hypoblast Chick Embryo

9. Images of human embryos during gastrulation,13 - 19 days post ovulation

11. Ectoderm, Mesoderm, and Endoderm
Trilaminar germ disc
Dynamic movement of cells to form three germ layers:
Ectoderm, Mesoderm, and Endoderm
1 Primitive groove 2 Primitive pit 3 Primitive node 4 Oropharyngeal membrane 5 Cardial plate 6 Sectional edge of amniotic membrane 7 Mesoderm 8 Endoderm 9Future cloacal membrane primitive streak
Rostral – beak; caudal tail

12. A cut through the embryo illustrates the three germ layers: ectoderm (formerly referred to as epiblast), mesoderm, and endoderm.
Mouse E7, Human ~17days

13. Ectoderm (OUTER LAYER)
Ectoderm forms tissues associated with outer layers: skin, hair, sweat glands, epithelium. The brain and nervous system develop from the ectoderm.
Mesoderm (MIDDLE LAYER)
The mesoderm forms structures associated with movement and support (skeleton and muscles): body muscles, cartilage, bone, blood, and all other connective tissues. Reproductive system organs and kidneys form from mesoderm.
Endoderm (INNER LAYER)
The endoderm forms tissues and organs associated with the internal organs (digestive and respiratory systems). Many endocrine structures, such as the thyroid and parathyroid glands, are formed by the endoderm. The liver, pancreas, and gall bladder arise from endoderm. p

15. The CNS forms from the walls of a fluid-filled neural tube
The inside of the tube becomes ventricular system
The neural tube
Endoderm, mesoderm, ectoderm
Neural plate  neural groove
Fusion of neural folds
Neural tube (forms Central Nervous System (CNS) neurons) :NEURULATION
Neural crest (forms Peripheral Nervous System (PNS) neurons)
Somites (form vertebrae of spinal column and related muscle)
p181

16. p181

17. Primary neurulation
p181

18. Neural Tube Related Birth Defects
Anterior
neural
pore
failure to close =
anencephaly
birth defects related to folic acid deficiency
Posterior
neural
pore
failure to close =
spina bifida
p 183

19. Neural crest becomes peripheral nervous system (PNS)
Neural tube becomes central nervous system (CNS)
Somites become spinal vertebrae.
Somites
p 181

20. Neural Crest Stem Cells
Crane and Trainor 2007
+ connective tissue around face and head
Peripheral Nervous System (PNS)
NP, neural precursor;
MP, melanocyte precursor; NGP, neuron/glia precursor;
CP, cardiac precursor.

21. Neural crest specification: migrating into genomics
Laura S. Gammill & Marianne Bronner-Fraser
Nature Reviews Neuroscience 4, (October 2003)

22. FROM THE NEURAL TUBE TO THE BRAIN
Closure of neural tube have around 125,000 cells.
At birth, the human brain contains around 100 billion neurons
We can infer from this information that new neurons are being generated at the rate of about 250,000 per minute during the nine months of gestation.
(Cowan, 1979)

23. Three-vesicle stage (Week 4)p

24. A cut through the recently closed cranial neural tube illustrates the
forebrain (prosencephalon),
midbrain (mesencephalon), and
hindbrain (rhombencephalon).
E10 mouse, human ~5 week

25. Five-vesicle stage mesencephalon metencephalon myelencephalon 4 weeks

26. Holoprosencephaly (HPE) is a congenital anomaly in which there is incomplete development of the brain.
Alobar HPE
Lobar HPE
In utero, the developing forebrain (prosencephalon) fails to divide into two separate hemispheres and ventricles. Specifically, there is incomplete cleavage into right and left hemispheres; into the telencephalon and diencephalons; and into the olfactory and optic bulbs and tracts. Based on the level of cleavage, holoprosencephaly is classified into 4 subtypes: Alobar, Semilobar, Lobar and MIHV.

27. Differentiation of Forebrain
The neurons of the telencephalon wall proliferate to form 3 distinct regions
cerebral cortex 2) the basal telencephalon, and 3) the olfactory bulb
The diencephalon differentiates into the thalamus and the hypothalamus
GREY MATTER: Collection of neuronal cell bodies in CNS
p 180, 184-5

28. Formation of Ventricles and White Matter
Ventricles: Fluid filed spaces: lateral and third ventricle
WHITE MATTER: Collection of CNS axons
Corpus Callosum: axonal bridge link cortical neurons from 2 hemispheres
p 180, 184-5

29. Differentiation of Midbrain
Function as passageway for the bundles of fibers that connect the cortex to the spinal cord (sensory and motor) p

30. Midbrain Structure Function
Contains axons descending from cortex to brain stem and spinal cord
e.g., Corticospinal tract
Information conduit from spinal cord to forebrain and vice versa, sensory systems, control of movements
Tectum  Superior colliculus (receives sensory info from eye), inferior colliculus (receives sensory info from ear)
Tegmentum
Substantia nigra (black substance) and red nucleus – control voluntary movement p

31. Differentiation of Hindbrain (Rostral / Caudal)
Rostral portion of the hindbrain differentiates into two major structures: the cerebellum and the pons. p

32. Hindbrain Structure Function
Cerebellum: Movement control
Pons: Switchboard connecting cerebral cortex to cerebellum
Cochlear Nuclei: Project axons to different structures (e.g., inferior colliculus)
Decussation:
Crossing of axons from one side
to the other p

33. TELENCEPHALON GIVES RISE TO MAJORITY OF STRUCTURES
Copyright © 2009 Allyn & Bacon

34. Differentiation of Spinal Cord
Movie: p

35. Putting the Pieces Together

36. Summary Gastrulation Formation of 3 germ layers Neurulation:
Formation of neural tube
3. Differentiation and Formation of the Major Subdivision of the Brain (Forebrain, Midbrain, Hindbrain) and Spinal Cord
Question Last Year

37. Fill in the blanks (answers in italics) (½ mark for each blank)
During the process of ___neurulation____ the neural tube is formed, which becomes the __brain__ and __spinal cord____ in the adult . (1 ½ marks).
Failure of the developing forebrain (prosencephalon) to divide into two separate hemispheres and ventricles results in a congenital anomaly called __holoprosencephaly (HPE)_(1/2 mark)
At the 3 vesicle stage of development of the embryo the prosencephalon is also called the forbrain. The prosencephalon gives rise to the __telencephalon____ and ___ diencephalon__ at the 5 vesicle stage of development. (1 mark)