neural development - neuro and synaptogenesis

embryogenesis

first ovum is produced by ganmetogenesis then is fertilized by sperm, zygote formed, then cleveage made, then morula forms, then blastulation occurs forming blastocyst, then it implants, then gastrulation occurs where the derms form, then neurulation occurs forming tube and crest, then somitogenesis forming yolk-sac, then organogenesis

describe neurulation the derms and where cns and pns comes from

ectoderm makes nervous system and skin, mesoderm makes bones and muscles, endoderm = lining of organs, mesoderm - muscle and connective tissue, ectoderm - brain and stem cells, endoderm - internal organs, cns = neural tube, pns = neural crest, refinement through cell death, where unnecssary neurons are ended

describe behavior of neurons

they first proliferate, and then they must undergo migration to be in the right place, and then the correct type of cell they differentiate, then neurons communicate through axon formations and synapse formation

cellular differentiation

specific cell type through taking appearance and characteristics of gene patterns and exposure to soluble factors

totipotent

can produce any type of cell

pluriopotent cell

can be any other cell through the body

mulitpotent sc

not all cells but more than one ,

progenitor stem cell

has already to commited to type of cells with limited option

precursor cell

lost most of its stem cell properties, partially differentiated

describe process of proliferation

cells are born in walls of five fluid filled vesicles, make up ventircular system in cns, early dev: two layers - ventricular zone, lines the ventricle and marginal zone, faces the pia mater

cell dance: cell in ventricular zone - reaches upward to pia, then nucelus of cell goes up from ventricular surface to pial surface = dna copied. then duplicated dna goes back down to ventricular surface, cell retracts arm into pial surface, and divides in two

forms radial glial cell, expand npc through symmetrical cell division, if even tf = symmetrical where both daughters in the ventricular zone to divide again, if uneven = assymetrical one stays in ventricular zone, other npc goes to cortex ,

how does migration occur

neural precursor cells climb radial glial cells in ventricular zone to migrate, npcs do this through extending the leading process and retracting trailing process, in inside out way to assemble cortex, cells stack on top of each other, earliest migrating cells = deepst, latest migrating cells = in most superficial layer

describe differentiation

stem cells are turned into specific cells, through inductive factors which are signaling molecules from other cells, diffuse or cell surface interactions, bind to cell receptors to encode proteins, if cell gets induced, it is compotent,

rostrocaudal and dosrovental patterning of neural tube

neural differentiation occurs in rostrocaudal pattern in neural tube then dorsoventral patterning, different molecular cues depending on location, allowing for specific development to occur within distinct regions along the axes to acquire identities and functions, different cells will encounter a gradient of cues which tells them to turn into a specific type of neuron, concentration differences of signaling cues = different tf expressions

axon growth and synapse formation

neurons comm with others with their axons even if its far, growth cones helps with elongation and finding the correct cell

axon or dendriten

neurons = polarized with two ends, distinct proteins, axons = tau, dendrites = map2, actin filaments in immature neurite that become destabilized = cytoskeletal arrangement = axons, rest become dendrites, semaphorins = trigger dendrite formation, axon guidance forms axon formation

how do axons know where to go

chemoaffinity hypothesis - axons provided for target location from chemical signals, axon = receptor that matches with complementary signal from target cell

synaptogenesis

axons find a target to connect with, they presynaptic and postsynaptic components are developed, then synapses mature and rearrange, based on env, they use cell adhesion molecules to find cells

cell death

target cells foe neurons release neurotrophic factor which is an essential nutrient which supports neurons, the hypothesis states that neurons getting their factor survive while other degenerate, and the fact helps block cell death signaling

refinement

ns makes a lot more synapses, pruning them helps make it more efficient, and it is refined by experiences and neural signaling