Lecture 9 - Development

Lecture 9 - Development

1. Anterior posterior polarity of the neural tube

   • The formation of the neural tube does not occur all at once along its full length
     • Begins in the middle at the embryonic day 20 (in humans) and then continues towards each end
       • Openings left at each end are called the anterior (cranial) and posterior (caudal) neuropores
         • Anterior neuropore closes on day ~25 and the posterior neuropore on day ~27
         • Somites are balls of mesoderm that mature into the segmented axial skeleton
           • Each pair is added sequentially from head to tail down the length of the embryo

2. Neural tube stem cell proliferation

   • Neural tube SCs give rise to all CNS nerve cells, atrocytes and oligodendrocytes
   • Day 33 - stem cells switch to an asymmetric mode of cell division

3. Formation of radial glial cells

4. Canonical Wnt signalling pathway - look at cell biology from last year

   • Involved in neural patterning
     • Wnt inhibitors (Dickkopf, Cerberus, Frzb, IGF = insulin-like growth factor) are made by dorsal anterior mesoderm and the organiser
     • Wnt controls posterior-anterior development of the nervous system
       • FGF and RA are also very important in anterior-posterior patterning
     • Gradients controlling dorso-ventral patterning