1 Biology 4361 Name: ______KEY_____________ Exam 3 ID#: _____________________ July 31, 2009 Multiple choice (one point each; indicate the best answer) 1. Neural tube closure is accomplished by movement of the a. medial hinge point cells. b. medial and dorsolateral hinge point cells. c. medial and dorsolateral hinge point cells, and surface ectoderm. d. medial and dorsolateral hinge point cells, surface ectoderm, and somite mesoderm. 2. Spina bifida is a medical condition caused by failure of a. the anterior neuropore to close. b. the posterior neuropore to close. c. cerebrospinal fluid production by the central canal. d. none of the above. 3. In the chick, secondary neurulation occurs a. in the most anterior region. b. in the most posterior region. c. throughout the entire embryo d. none of the above. 4. In human skin, replacement cells are first formed in the a. cornified layer. b. granular layer. c. germinal layer. d. all of the above. 5. Neurons are produced in the __________________ of the neural tube. a. ventricular zone b. intermediate zone c. marginal zone d. sulcus limitans 6. In humans the rate of neuronal formation a. increases from birth until mid-childhood. b. decreases over the first several years of life. c. stops completely after the first year of life. d. remains at the same rate as seen in the late fetus until mid-childhood. 7. Cranial neural crest cells contribute to which structures? a. inner ear bones, cranial nerves b. thymus cells, jaw c. facial cartilage, facial bone d. all of the above2 8. Trunk neural crest cells are specified a. prior to migration. b. during migration. c. by paracrine factors after arrival at their destination. d. none of the above. 9. Problems with cardiac neural crest cell migration might be expected to result in defects in the a. specification of atrial and ventricular regions. b. division of the aorta and pulmonary arteries. c. placement of the vitelline artery. d. none of the above. 10. Trunk neural crest cells that migrate into and remain in the adjacent somite become a. melanocytes. b. interneurons. c. dorsal root ganglia. d. parasympathetic ganglia. 11. Neural crest cells that form part of the adrenal gland a. originate in the vagal region. b. migrate late. c. migrate through the ventrolateral pathway. d. all of the above. 12. Osteocytes secrete a matrix consisting of a. calcium-phosphate b. collagen and proteoglycans. c. osteoid proteins. d. none of the above 13. Subdivisions of mesodermal lineages are specified by BMP gradients which are a. high anterior, low posterior. b. high dorsal, low ventral. c. high ventral, low dorsal. d. high distal (or lateral), low proximal. 14. Specification of somites a. occurs early, in the pre-somitic mesoderm. b. occurs early, as the individual somites are being formed. c. occurs midway through the formation of individual somites. d. occurs late, after formation of individual somites. 15. What tissue is induced by MyoD? a. Intramembranous bone b. Tendon c. Muscle d. Ligament3 16. Which genes are probably responsible for the differential specification of somites producing cervical and thoracic vertebrae? a. BMPs b. Wnts c. Hox d. FGFs 17. Alignment of myoblasts into myotubes involves a. cell-to-cell communication. b. extracellular matrix proteins. c. cadherin. d. all of the above. 18. In male mammals, the mesonephric tubules and duct become a. ureters. b. metanephrogenic mesenchyme. c. efferent ducts, epididymus, and vas deferens. d. nothing; they disappear through apoptosis. 19. Cardiogenic mesoderm is induced by signals from the a. primitive streak. b. notochord. c. neurectoderm. d. endoderm. 20. Hemangiogenic mesoderm is induced by a. Wnt from the neural tube and ectoderm. b. Shh from the neural tube. c. Wnt from pharyngeal endoderm. d. none of the above. 21. Cushion cells, which form the heart valves, arise from a. ventricular myocytes. b. epidermal ectoderm. c. endoderm. d. endocardial endothelial cells. 22. Which gene activity is involved with cardiac looping? a. Notch. b. Nodal. c. Noggin. d. Neural. 23. Blood vessels consist of an inner layer of _________cells and an outer layer of __________ cells. a. hemangioblast, angioblast b. angiocyte, vasculocyte c. mesenchymal, epithelial d. endothelial, periendothelial4 24. During early embryonic development, most of the blood supply comes from the a. blood islands. b. yolk sac. c. liver. d. bone marrow. 25. Hindlimbs are specified by the presence of a. Tbx4 b. Tbx5 c. Tbx6 d. none of the above. 26. The AER function can be replaced by a. Shh b. BMP c. Wnt d. Fgf 27. Which proteins stabilize Fgf10 in the lateral plate mesoderm to initiate limb bud formation? a. Shh b. BMP c. Noggin d. Wnt 28. Gremlin acts in the early limb bud as a. a BMP antagonist. b. an Shh antagonist. c. a repressor of Gli3 transcription. d. none of the above. 29. In mice, digit 3 is specified by _______________ signaling. a. paracrine b. autocrine c. paracrine and autocrine d. juxtacrine 30. Limb dorsal-ventral patterning is under the control of a. Shh b. BMP c. Noggin d. Wnt5 True / False (one point each) 31. The ventricular zone of the neural tube consists of multiple layers of germinal epithelium. True/ False 32. Myelination of human brain neurons is completed during the third trimester of pregnancy. True/ False 33. Trunk neural crest cells migrating via the dorsolateral pathway contact the ectoderm. True / False 34. The positional identity of an individual somite is established by the particular neural crest cells that migrate through it. True / False 35. Specification of somite subdivisions (e.g. sclerotome, dermamyotome, etc.) is established in the pre-somitic plate stage. True / False 36. The endothelial lining of the heart arises from mesoderm. True / False 37. Blood vessels are not specified as veins or arteries until after they have formed. True / False 38. The tonsils are derived from endoderm of the 2nd pharyngeal pouch. True / False 39. Wnt proteins stimulate the degradation of Fgf10 in the lateral plate mesoderm, thereby initiating limb bud formation. True / False 40. Overexpression of Shh in the limb bud would cause additional