ISBN-13: 9781455706846 978-1455706846
Schoenwolf et al.: Larsen’s Human Embryology, 5th Edition
Chapter 3: Third Week: Becoming Trilaminar and Establishing Body Axes
1. A researcher inactivates Lefty1, a gene expressed in the anterior visceral endoderm of the mouse. What effect would inactivation of this gene have on the gastrula-stage embryo?
A. The epiblast becomes abnormally thickened throughout its cranial-caudal extent.
B. The primitive streak fails to form.
C. The endoderm fails to form.
D. The neural plate fails to form.
E. Extra primitive streaks form.
2. A boy is admitted to the hospital for an emergency appendectomy. During surgery it is noted that the inflamed appendix is located on the left side, rather than the right side, and that the patient has situs inversus viscerum totalis. Mutations in which gene are known to cause this condition in animal models?
3. A man with recurrent respiratory infections and infertility is diagnosed with Kartagener syndrome. Mutations in the gene encoding which protein cause this syndrome?
4. Rieger syndrome, which affects development of both the teeth and eyes, results from haploinsufficiency in which gene in humans?
5. Patterning of the mesoderm involves so-called dorsalizing and ventralizing factors. Inactivation of which protein(s) in the early embryo would be expected to result in dorsalized mesoderm?
6. A researcher knocks out the Tbx6 gene in a mouse. Which tissue will not form in the early embryo?
A. Neural plate
C. Lateral plate mesoderm
7. Which tissues ingress through the cranial end of the primitive streak?
A. Prospective neural plate
B. Prospective cardiogenic mesoderm
C. Prospective extraembryonic mesoderm
D. Prospective surface ectoderm
E. Prospective lateral plate mesoderm
F. Prospective placodal ectoderm
8. Alagille syndrome involves a failure of proper segmentation of the paraxial mesoderm, ultimately resulting in defects of the vertebral column. Which signaling pathway is mutated in patients with Alagille?
C. Tyrosine Kinase
9. Caudal dysplasia results from defects in which developmental process?
10. In a classical experiment, a portion of an amphibian gastrula was transplanted to the belly region of another embryo, resulting in the formation of a secondary embryo organized by the graft from host tissue. The equivalent area of the human embryo that would be expected to have similar organizer activity is what structure?
C. Cardiac mesoderm
D. Cloacal membrane
E. Body fold