CMM/BIO4350
Tues March 20, 2012
Diane Lagace, PhD
Assistant Professor
Department of Cellular and Molecular Medicine (CMM)
Neuroscience Program
RGH, Room 3510G, University of Ottawa,
dlagace@uottawa.ca
7 Lectures
1.
Embryonic Development 101
Chapter 7: Understanding CNS structure through development (p178-201)
2.
Gross Neuroantaomy
Chapter 7: Gross Organization of Mammalian Nervous System (p168-176)
Chapter 7 Appendix: Illustrated Guide to Human Neuroanatomy (p206-248)
3.
The Genesis of the Neuron (Neurogenesis) and Neuronal Connections
Chapter 23: The Genesis of Neuron, Connections and Elimination of Cells and Synapses
(p690-707)
4.
Regeneration of the Nervous System
From lecture notes only; not in text book
5.
Chemical Controls of Brain and Behavior
Chapter 15: Hypothalamus, ANS, Neurotransmitter Systems (p482-504)
6.
Motivation and Homeostasis
Chapter 16: Feeding Regulation Short and Long-Term and Why We Eat (p510-527)
7.
Sex and the Brain
Chapter 17 (p534-561)
What Do I Need to Know?
Text book
Notes
Both
Outline Lecture #1
1. Gastrulation
Formation of 3 germ layers (not in text book)
2. Neurulation:
Formation of neural tube (p. 180-183)
3. Differentiation and Formation of the Major Subdivision of the Brain
Forebrain, Midbrain, Hindbrain (p. 182-190)
4. Differentiation of the Spinal Cord (p. 190-191)
5. The Cerebral Cortex (p 195-199) Thursday
How Does the Brain and Spinal Cord Develop?
Video
http://www.youtube.com/watch
?v=UgT5rUQ9EmQ
Human Development
Inner Cell Mass Forms 2 Layer: Epiblast and Hypoblast
Chick Embryo
http://www.gastrulation.org/Movie15_1.avi
http://www.usm.maine.edu/bio/courses/bio205/bio20
ment_1.html
http://www.usm.maine.edu/bio/courses/bio205/bio205_05__de
ml
Images of human embryos during gastrulation,13 - 19 days post ovulation
http://biology.kenyon.edu/courses/biol114/Chap14/Chapter_14.html#Neurulation
http://stemcells.nih.gov/info/scireport/appendixa.asp
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
1+2+3 primitive streak
http://www.embryology.ch/anglais/hdisqueembry/triderm01.html#formligneprim
A cut through the embryo illustrates the three
germ layers: ectoderm (formerly referred to as
epiblast), mesoderm, and endoderm.
Mouse E7, Human ~17days
http://biology.kenyon.edu/courses/biol114/Chap14/Chapter_14.html
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 180-181
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
p181
Primary neurulation
p181
Neural Tube Related Birth Defects
Anterior
neural
pore
failure to close =
anencephaly
Posterior
neural
pore
failure to close =
spina bifida
p 183
• Neural crest becomes
peripheral nervous
system (PNS)
• Neural tube becomes
central nervous
system (CNS)
• Somites become
spinal vertebrae.
Somites
p 181
Neural Crest Stem Cells
Peripheral Nervous System (PNS)
+ connective tissue around face and head
NP, neural precursor;
MP, melanocyte precursor;
NGP, neuron/glia precursor;
CP, cardiac precursor.
Crane and Trainor 2007
Neural crest specification: migrating into genomics
Laura S. Gammill & Marianne Bronner-Fraser
Nature Reviews Neuroscience 4, 795-805 (October 2003)
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)
http://faculty.washington.edu/chudler/dev.html
Three-vesicle stage
(Week 4)
p 182-184
A cut through the recently closed cranial neural tube illustrates the
forebrain (prosencephalon),
midbrain (mesencephalon), and
hindbrain (rhombencephalon).
E10 mouse, human ~5 week
http://www.med.unc.edu/embryo_images/unitnervous/nerv_htms/nerv009.htm#
Five-vesicle stage
mesencephalon
metencephalon
myelencephalon
4 weeks
6 weeks
p 185
Holoprosencephaly (HPE) is a congenital anomaly in which there is
incomplete development of the brain.
Alobar HPE
Lobar HPE
http://www.ncbi.nlm.nih.gov/books/NBK1530/
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.
http://www.ninds.nih.gov/disorders/holoprosencep
/holoprosencephaly.htm
Differentiation of Forebrain
The neurons of the telencephalon wall proliferate to form 3 distinct regions
1)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
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
Differentiation of Midbrain
Function as passageway for the bundles of fibers that connect the cortex to
the spinal cord (sensory and motor)
p 187-188
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 187-188
Differentiation of Hindbrain (Rostral / Caudal)
Rostral portion of the hindbrain differentiates into two major
structures: the cerebellum and the pons.
p 188-189
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
http://www.youtube.com/watch?v=9BaWBGRVxp8&feature=related
p 188-189
TELENCEPHALON GIVES RISE TO MAJORITY OF STRUCTURES
Copyright © 2009 Allyn & Bacon
Differentiation of Spinal Cord
Movie: http://www.youtube.com/watch?v=LwuV5JbgCNk
p 190-191
Putting the Pieces Together
p 192
Summary
1. Gastrulation
Formation of 3 germ layers
2. 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
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)