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The vertebrate body plan. Humans, as vertebrates, are a subset of the chordates. Defined by presence of notochord. Amphioxus is the most famous non-vertebrate chordate (important in developmental biology). Cephalochordates (Amphioxus). Urochordates (Sea Squirts). We are segmented animals rhombomeres and somites..
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1. DB3802Development of Organ Systems Introduction.
Basic Tissue Types.
2. The vertebrate body plan
5. Paired sense organs
Limbs
Bones (vertebrae)
Squishy bits
6. Patterning and differentiation are not the same thing The right tissues can all be present, but in the wrong place
7. Basic tissue types… Epithelia… many organs are of substantially epithelial origin – e.g. the brain.
(Neural tissues)
Connective tissues (also includes fat and skeleton)
Muscles
Blood and blood vessels.
Need to study… tissue organisation, stem cells, development of mesodermal organs (somites, myogenesis, kidney and gonads, limbs, heart), development of endodermal organs (gut, pancreas,liver)
10. Epithelia
11. Epithelial junctions Tight junctions
Specialised proteins e.g. claudins. Prevent free apical/basal diffusion of small molecules across epithelium
Adherens junctions
Cadherin-mediated attachment to actin cytoskeleton
Desmosomes
cadherins (e.f. desmoglian) attachment to intermediate filament-based cytoskeleton.
(Hemidesmosomes -integrin-based attachment to basement membrane)
Gap junctions
connexin-based, allow passage of molecules between cells
12. Neural tissue The neuroepithelium – develops from the thickened neural plate (neural induction)
Gives rise to CNS
and neural crest
13. Connective Tissue Conventionally characterised by fibroblast contribution
14. Connective Tissue
15. Muscle
16. The circulatory system
17. The circulatory system
18. Summary Development of organ systems involves
1) Patterning – cells knowing where they are… and
2) differentiation into appropriate tissue types through activation of correct genetic programme dependent on cellular location and interaction with surrounding cells and tissues.
Fundamentally there are not really all that many tissue types.
Organ development is a huge problem to understand, but not totally intractable.