2009 Lecture 23

From CellBiology


CSt1 zygote.gif Human CST23.gif


The image above shows the first cell that forms following fertilization, and that cell's offspring 8 weeks later.

This lecture follows on from the stem cell lecture and discusses how specific cell types arise and differentiate during development.

What are the mechanisms that regulate differentiation?
What do these signals do?

Developmental Models

  • What makes one cell different from the next?
  • Developmental Models
    • drosophila- fruit fly
    • c. elegans- worm
    • xenopus- frog
    • zebrafish- fish
    • chicken- bird
    • mouse- mammal

Background to Patterning

  • All cells contain the same genetic material and are initially equipotent
  • Development is about pattern formation
  • axis and tissue formation

Regulators of pattern - signaling

  • Contact (cell-cell, cell-ECM, surfaces)
  • Morphogen (soluble, modified)
  • Time
    • “window”, undifferentiated/differentiated, stem
  • Genome modification, regulators

Drosophila Development Model

Position-Specific Patterning

Cascade of short range inductions

Secretion of long range signal

Long range secondary signal from primary inductive

spinal cord /neural crest, examples of complex structure generated by such a signalling process

Short Range Inductive Cascade

Long Range Signal

Long Range Secondary Signal from Primary Inductive

Developmental Mechanisms

Epithelial Mesenchymal Transition

Chicken gastrulation
Chicken gastrulation
  • A morphogenetic process in which cells lose their epithelial characteristics and gain mesenchymal properties


  • cells build up matrix proteins around them and at the same time are actively migrating
    • early mesoderm migration suggested as generated from 3 types of contact
      • basal side of the ectoderm
      • basal side of the endoderm
      • with each other
  • directional migration requires orientation of Golgi complex and centrosome relative to nucleus position

Links: Epithelial Mesenchymal Transition | PMID: 19262172


Links: PMID: 19029939




  • Essential Cell Biology
    • Chapter
  • Molecular Biology of the Cell

Search Online Textbooks


  • An amicable separation: Chick's way of doing EMT. Nakaya Y, Sheng G. Cell Adh Migr. 2009 Apr;3(2):160-3. Epub 2009 Apr 10. PMID: 19262172 | Landes - PDF

2009 Course Content


Cell Biology Introduction | Cells Eukaryotes and Prokaryotes | Cell Membranes and Compartments | Cell Nucleus | Cell Export - Exocytosis | Cell Import - Endocytosis | Cell Mitochondria | Cell Junctions | Cytoskeleton Introduction | Cytoskeleton 1 Intermediate Filaments | Cytoskeleton 2 Microtubules | Cytoskeleton 3 Microfilaments | Extracellular Matrix 1 | Extracellular Matrix 2 | Cell Cycle | Cell Division | Cell Death 1 | Cell Death 2 | Signal 1 | Signal 2 | Stem Cells | Stem Cells | Development | Revision


Introduction to Lab | Microscopy Methods | Preparation/Fixation | Immunochemistry | Cell Knockout Methods | Cytoskeleton Exercise | Confocal Microscopy | Tissue Culture 1 | Tissue Culture 2 | Microarray Lab visit

Dr Mark Hill 2015, UNSW Cell Biology - UNSW CRICOS Provider Code No. 00098G