BIPN 140 Lecture 15 11.16.10

BIPN 140 Lecture 15 11.16.10 - I. Early Brain Development...

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I. Early Brain Development Flight Plan (Outline): Start off with a discussion of Neuroinduction (determination – determining the commitment of the tissues of the embryo to become the nervous system) Then we will talk about proliferation – what controls how many neurons are made during the course of the development of the NS and where they are made is not where they sit and where they act and where they make connections is somewhere else and to get there, there is a major phase of early development (migration)—of neurons to the sites where they are generated to where they are sitting Differentiation of excitability-we have previously talked about differentiation and excitability and Aps a lot from Darwin about transmitters Development of neurotransmitter synthesis- 2. Induction: setting up the body plan/organizing tissues and cells -starts off with Fertilization of the egg mitosis (divisions) blastula (hollow ball of cells and some cells have nuclei and inside there is a blasocyll a hollow ball in the cavity) invagination punches the cell to produce a gastrula (very important time your life) you get the three tissue layers (ectoderm, endoderm, and mesoderm) -Formation of notochord (from the mesoderm) -Mesoderm ectoderm signaling = primary induction -Experiment: Spemann & Manngold and took the dorsal lip of the blastopore = organizer region and implant the dorsal lip of the blastophore applied ventrally which they got a Siamese twins frog larvae -The neural plate (state of invagination) neural groove (pinches off and closes up to form) neural tube. Neural crest (bits of tissue left out), from the ridges of the neural groove. Neural Crest gives rise to sensory ganglia (dorsal root ganglia - DRG) also gives rise to the autonomic ganglia (parasympathetic and autonomic NS) also gives rise to the adrenal medulla, bone, and etc -The notochord sends signals to the ectoderm to invaginate. Somites give rise to muscle tissue. -Roofplate, floorplate, notochord, somites: sources of inductive signals -Neural precursor cells: progenitor cells of neural tube/stem cells -Neuroblasts: post-mitotic/not dividing/differentiate into neurons - Crest materials migrate which their fate depends on where they migrate: Figure 22.2 on lec 13 powerpoint slides right side of figure shows where they migrate what they will become: 1. Dorsal Root Ganglia 2. Autonomic Ganglia 3. Adrenal Medulla 4. Pigment Cells 3. Induction: the molecular basis
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-Overview of general principle: various ligands bind receptors that signal to the nucleus (often by migrating directly), bind to DNA alter gene transcription (alter RNA synthesis) (inhibiting or expressive) -Retinoic acid – one important molecule involved in the induction process: binds to RA receptors which migrate to the nucleus, bind to DNA. Downstream targets? We are not going to go there girlfriend! -BMPs – born morphogenetic proteins, signaling molecule, members of a large family of TGF
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BIPN 140 Lecture 15 11.16.10 - I. Early Brain Development...

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