final exam all bio 4400, Cell Fate and Specification, Exam 2: Neurulation, Exam 2: Neurons, Exam 2 - Neural Crest cells, Exam 2: Sensory placodes and organs, Cell-cell interactions and signaling

Ectoderm doesn't move through the __________ or __________ - CORRECT ANSWER 1) blastopore (frogs and fishes) or 2) primitive streak (birds and humans) Sensory organs all begin in the head as... - CORRECT ANSWER placode - thickenings of surface ectoderm what are 4 types of cell interactions? - CORRECT ANSWER 1) Internal/mechanical 2) Juxtacrine signaling 3) Paracrine signaling 4) Endocrine signaling Note: these are arranged in order of closest interaction to longest distance interaction The 6 word key to development: - CORRECT ANSWER Find it - mRNA or protein has to be in the right place (at the right time) in order for a developmental step to take place Move it - moving specific cells to a new location - does this start a new process? if so then, those cells are probably important for the process Neural crest cells as the _________ only in vertebrates! Neural crest cells as the _________ because of their extensive migration - CORRECT ANSWER 1) "4th germ layer" 2) "the explorers of the embryo" Patterning of neural tube (CNS):- anterior to posterior via _________. - dosal to ventral via ________ and ________ - CORRECT ANSWER 1) Hox genes 2) BMP and Shh gradients Three fundamental rules of development: - CORRECT ANSWER 1) Timing is everything 2) Location, location, location 3) Both of the above are true Ectoderm in birds and humans vs. frogs and fishes - CORRECT ANSWER Birds and humans: - Ectoderm = Epiblast that does not ingress Frogs and Fishes: - Ectoderm = epithelia that undergoes epiboly and remains on outside what is the another name for the cell body of a neuron? - CORRECT ANSWER Soma Neural crest cell derivatives - CORRECT ANSWER *INTERMEDIATE BMP LEVELS* 1) Adrenal medulla 2) Craniofacial bones and cartilage 3) Dentine of teeth 4) Melanocytes 5) PNS - Glial cells - Schwann cells - Sympathetic and Parasympathetic nervous systems cranial placodes: - CORRECT ANSWER 1) Olfactory 2) Lens 3) Otic what are the two major types of cells in the embryo? - CORRECT ANSWER Epithelium 1) Highly organized into sheet or tube 2) Tightly linked together - Junctional complexes (*cadherins*) 3) Stationary 4) Polarized (apical side vs. basal side) 5) little ECM Mesenchyme 1) Loosely organized 2) Loss of adhesion 3) Ability to migrate and invade - most cancer cells that are metastasizing are mesenchyme - can operate as an independent unit 4) No polarity 5) Lots of ECM lessons from development: Who you surround yourself with... - CORRECT ANSWER changes your path. - Your community and neighbors are important. what are the 3 primary ectoderm derivatives? - CORRECT ANSWER 1) Neural plate (Neural tube) - BMP levels are low - Sox transcription factors expressed 2) Neural crest cells - BMP levels are moderate 3) Epidermis (surface) ectoderm - BMP levels are high Myelination of axons in the CNS via... - CORRECT ANSWER Oligodendrocytes when does neural crest cell development begin? (weeks post fertilization) - CORRECT ANSWER ~3-4 weeks post fertilization Like neural crest cells, sensory placodes form at... - CORRECT ANSWER intermediate BMP levels Cell adhesion complexes - Cadherins - CORRECT ANSWER *Calcium dependent adhesion* 1) connect to actin microfilaments 2) bind in a homophilic (tissue specific) manner ex: E-cadherin binds more strongly to another E-cadherin than N-cadherin, and vice versa *cell sorting based on type and # of cadherins present* when is sensory placode induction and specification initiated in humans? - CORRECT ANSWER ~3-4 weeks post fertilization (around neurulation) Cadherins:pattern formation via... - CORRECT ANSWER differential affinity based on intrinsic properties of cell adhesion proteins (cadherins) ex: if you mix two different cell types and then take a cross section of them, *the cell type with more cadherin will be in the center* and the cell type with less on the periphery lessons from development: ____________ matters! - CORRECT ANSWER Context! The response to a signal depends on: 1) other signals 2) neighbors, 3) the type of tissue 4) the competence of a cell to receive that signal. Steps of neural crest cell development (4 of them) - CORRECT ANSWER 1) Induction and determination 2) Concurrent delamination and epithelial-to-mesenchymal transition (EMT) 3) Migration 4) Differentiation Non-neuronal (supporting) cells known as ________ are necessary for proper functioning of neurons - CORRECT ANSWER Oligodendrocytes - they myelinate the axons of neurons Ectoderm derivatives: Neural plate (neural tube) - CORRECT ANSWER *LOW BMP LEVELS* 1) CNS (brain and spinal cord) 2) Neural pituitary 3) Motor neurons 4) Retina of eye lessons from development: Local changes can... - CORRECT ANSWER have a global impact. Ectoderm derivatives: