1Biology 4361 Name:______KEY__________ Exam 4 ID#: ____________________ August 1, 2008 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. Neurons in the central nervous system are myelinated by a. glial cells. b. Schwann cells. c. oligodendrocytes. d. myelinocytes. 3. 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. 4. Neural tube cells are specified by opposing dorsal-ventral gradients of a. Wnts and Nodal. b. FGF and Shh. c. BMPs and Wnts. d. BMPs and Shh. 5. In human skin, replacement cells are first formed in the a. cornified layer. b. granular layer. c. germinal layer. d. all of the above. 6. Neurons are produced in the __________________ of the neural tube. a. ventricular zone b. intermediate zone c. marginal zone d. sulcus limitans 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 above28. 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. Vagal neural crest cells contribute to formation of a. melanocytes. b. adrenal medulla. c. parasympathetic ganglia of the gut. d. none of the above. 10. Trunk neural crest cells migrate a. exclusively around the somites. b. exclusively through the somites. c. around and through the somites. d. into the pharyngeal pouches. 11. 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 lateral, low proximal. 12. The Notch receptor is thought to play a key role in which part of somitogenesis? a. The clock and wave mechanism. b. Periodicity. c. Fissure formation. d. all of the above. 13. Recent evidence suggests that differences in somite numbers between vertebrate species may be the result of a. differences in the length of the pre-somitic mesoderm. b. use of mechanisms other than the “clock and wave" c. faster cycling of the “clock” mechanism. d. none of the above. 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. Tongue muscle is derived from the a. sclerotome. b. primaxial myotome. c. abaxial myotome. d. none of the above.316. What tissue is associated with MyoD? a. Intramembranous bone. b. Endochondral bone. c. Muscle. d. Ligament. 17. The presence of the transcription factor _______ is diagnostic of the ________ . a. BMP, sclerotome. b. Nodal, myotome. c. Shh, dermatome. d. scleraxis, syndetome. 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. Cardiogenenic mesoderm forms a. early in gastrulation. b. late in gastrulation. c. in the neurula stage. d. in the organogenesis stage. 20. Cardiogenic mesoderm is induced by signals from the a. primitive streak. b. notochord. c. neurectoderm. d. endoderm. 21. Cushion cells, which form the heart valves, arise from a. ventricular myocytes. b. epidermal ectoderm. c. endoderm. d. endocardial endothelial cells. 22. The heart is specified in a rostral-caudal axis by a. Shh. b. BMPs. c. Wnts. d. retinoic acid. 23. During human development, the aortic arches a. are all retained. b. either disappear or form various arteries. c. eventually disappear. d. none of the above.424. Primary capillary networks are remodeled during a. extraembryonic vasculogenesis. b. intraembryonic vasculogenesis. c. angiogenesis. d. capillogenesis. 25. Venous and arterial capillaries join via which ligand/receptor combination? a. Delta/Notch b. Shh/Patched c. Fgf2/FGFR d. none of the above. 26. Human gut formation involves a. somatic mesoderm. b. splanchnic mesoderm. c. somatic ectoderm. d. splanchnic ectoderm. True / False (1 point each) 27. Neural crest cells travel exclusively along pathways delineated by extracellular matrix molecules. True / False 28. Trunk neural crest cells migrating via the dorsolateral pathway contact the ectoderm. True / False 29. The ventricular zone of the neural tube consists of multiple layers of germinal epithelium. True / False 30. The initial expansion of the anterior neural tube is caused by cell proliferation in the ependymal layer. True / False 31. Newly formed neurons migrate through layers of neurons that preceded them. True / False 32. Myelination of human brain neurons is completed during the third trimester of pregnancy. True / False 33. Blood vessels generally start forming after the heart starts beating. True / False 34. Proliferating chondrocytes are induced to become hypertrophic by the transcription factor Runx2 (Andy’s question). True / False 35. Hematopoietic stem cells form red blood cells; lymphoid stem cells form white blood cells. True / False 36. The tonsil is derived from the lateral plate mesoderm of the pharyngeal pouch. True / False5Fill in. Indicate the location of each of the following structures, cells, or tissues. Label each with a line, arrow, or circle. (½ point each) 37 – 50. Indicate where each of the following cells, structure or organs originate. Label each with a line, arrow, or circle. (½ point each) 51 – 64. abaxial myotome dermamyotomeendoderm epidermal ectodermintermediate mesoderm lateral plate mesodermneural crest cells neural tubenotochordsomitesclerotomesomatopleure spalnchnopleure primaxialmyotomeallantois amnion dermal layer of skin