BIOL130 Lecture Notes - Paraxial Mesoderm, Olfactory Bulb, Fasciculation

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Published on 28 Jan 2013
Eyes, Ear, Nose
Sensory Receptor Cells
sensory cilia – related to motile cilia, but central tubules are missing
Light: rod photoreceptor
uses rhodopsin and G-protein pathway for a.p. and nt release
Sound: ciliary movement directly opens/closes membrane channels
hair cells
Chemicals: rhodopsin-like receptors
G-protein coupled cascade to amplify original signal
1,000 different odorants can be detected
Genetic defects of cilia more than one cell affected (Usher’s Synd.)
Early Evolution of Vertebrate sensory organs:
cilia project from apical surface of epithelia
least protected = olfactory epithelium
mechanosensory cells – more extensive infolding
photoreceptors – most extensive evolution
folded into the neural tube must face AWAY from light
Sensory cell origins: embryonic primordia
EYE – forebrain epithelium grows out becomes OPTIC VESICLE
vesicle becomes retina
lens forms from ectoderm
EAR/NOSE – from thickened surface ectodermal PLACODES
ear: otic placode otic vesicle hair cells
nose: olfactory placode
**primordial tissues are source of neurons AND
inductive signals for rest of organ**
hair cell
Usher’s Syndrome
optic vesicle
ectodermal placodes
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