L4 - Embryology Flashcards
Neural induction
Assigning neural potential to a region of early embryo
Neuralation
Forming the rudimentary NS (neural tube)
Neurogenesis
Production of neurons and glia from precursor cells
What determines epidermal fate? What blocks it?
Epidermal fate is determined by local bone morphogenetic protein (BMP) signalling.
Signals from “organizer” region underneath epidermis layer (Noggin, Chordin) block the BMP signal inducing neural fate.
*Chick embryo, the organiser is aka Hensen’s node, in human embryo - the node
Human embryonic development
1) 2 cell stage
2) 4 cell stage
3) Blastula -hollow sphere of cells
4) Blastocyst -differentiation of cells has occurred
5) Implantation
6) Embryo gastrulation- the single-layered blastula is reorganized into a trilaminar (“three-layered”- ectoderm, mesoderm, and endoderm)
7) Neurula - First appearance of NS
Neural tube zips up uni or bidirectionally?
Bidirectionally
Be Smart Smell Hair Booty
Formation of neural tube (neurulation)
Transformation of neural plate into neural tube - Elevation of neural folds, neural folds fuse in dorsal midline, neural tube pinched off from epidermis
What do neural crest give rise to?
Peripheral and enteric NS ganglia, melanocytes, schwann cells, cartilage and bone (face, jaw), cells in adrenal medulla
Overlying ectoderm induces roof plate that secretes
Dorzalizing morphogens (BMPs, Fibroblastic Growth Factors, Wnts)
Underlying notochord induces floor plate that secretes
Ventralizing morphogen (sonic hedgehog)
The brain vesicles/neural tube initially consist of a single or multi layer of neuroepithelial cells?
Single
Appears multi-layered because the nucles and cell body move to different positions along the apical-basal axis with different phases of cell cycle
Symmetric divisions give rise to two identical or different daughter cells? What about asymmetric divisions?
Identical, different
The order of cortical layer formation is “inside out”. What does this mean?
The deepest cellular layers are assembled first and those closest to the surface last.
Where are cortical interneurons produced?
In the basal forebrain (MGE - Medial ganglionic eminence)
Olfactory bulb neuroblasts migrate along ____
The rostral migratory stream
Cerebellar granule cell precursors migrate from ___
Rhombic lip
Neurogenesis preceed gliogenesis
Production of neurons and glia is controlled by separate transcriptional programs, each blocks the other
80% of neurons in cortex are
Pyramidal neurons - excitatory long range projection neurons
20% of neurons in cortex are
Interneurons - locally projecting inhibitory neurons that modulate cortical excitatory output
Growth cones are made from ___ which carry out what sort of functions?
Actin filaments - regulate shape and directed growth of growth cone
Microtubules - provide structural support to axon shaft and are essential for axon extension
Filopodia (On growth cone)
Thin, actin-rich plasma-membrane protrusions that function as antennae for cells to probe their environment
Critical period where sensory input from left and right eyes rearranges developing circuits into occular dominance columns is within _ weeks
At 6 weeks, occular dominance columns look normal.
