DevelopmentW2010.Lecture10notes - Development BIO 120...

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Development BIO 120 Winter 2010 Jeremy Lee Patrick Yuh Eva Murdock Lecture 10 Differentiation of the Neural Crest and the Epidermis I. Formation of the Neural Crest Cells a. Neural crest cells are derived from cells found at the neural folds during neurulation (Fig. #1) b. Presumptive epidermal cells express E-cadherin and neural tube cells express N-cadherin and N- CAM . Some cells, initially expressing N-cadherin and N-CAM, downregulate their production of these molecules and upregulate the slug gene, which encodes a specific transcription factor. These cells become migrating neural crest cells. c. Experiments indicating slug gene involvement in neural crest migration. 1. Determination of the expression pattern of slug mRNA and Slug protein by in situ hybridization (Fig. #2). Indicates slug mRNA and protein are found in neural crest cells. 2. Anti-sense RNA . Incorporating into the embryo anti-sense RNA to slug mRNA. The slug anti-sense RNA binds to slug mRNA and prevents translation of slug mRNA into Slug protein, so little or no Slug protein is made. This addition of anti-sense slug RNA prevented migration of neural crest cells, indicating the importance for neural crest migration of the Slug protein. d. Neural crest cells migrate from the space between the presumptive epidermis and the neural tube. e. Neural crest cells are among the most pluripotent cells, developing into a wide variety of cell types. As they migrate and divide, they differentiate and become less pluripotent (Figs, #3, #4) II. Developmental Fates of Neural Crest Cells (Figs. #5.1, #5.2) a. General regions/functional domains within which they migrate. 1. Cephalic neural crest (head): bones, cartilage, neurons, glia and connective tissue of the face, tooth primordia, thymic cells, jaw and inner ear cartilage 2. Trunk neural crest: melanocytes of skin; neurons in the dorsal root (sensory) ganglia, in the sympathetic ganglia, and surrounding the aorta; and endocrine cells in the adrenal medulla. 3. Vagal and sacral neural crest (anterior to, and posterior to trunk, respectively): neurons of the parasympathetic ganglia, including cervical ganglia 4. Cardiac neural crest: cells of the septum between the pulmonary artery and the aorta, connective tissue and smooth muscle of large arteries near heart. b. Specific migratory pathways of neural crest cells; example: trunk neural crest cells. 1. Neural crest cells migrate through and around somites, temporary segmental structures derived from mesoderm that surround the neural tube. (Figs. #6.1, #6.2, #6.3) 2. Some neural crest cells migrate between the epidermis and the dermamyotome (outer part of somite.) (Fig. #7) These cells will become melanocytes (pigment cells in the skin.) 3. Some neural crest cells migrate in the anterior part of each somite, within the
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This note was uploaded on 03/30/2010 for the course BIOLOGY 125 taught by Professor Jeremylee during the Winter '10 term at University of California, Santa Cruz.

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DevelopmentW2010.Lecture10notes - Development BIO 120...

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