PATTERN

  1. How could the developmental defect of wingless chicken mutants be detected?
  2. 1. What can eye and heart field development tell us about fields in general?
  3. Describe experiments to determine when the axes of a field are determined.
  4. 3. When the distal half of a paddle stage limb bud is removed, the proximal part of the limb, only, is formed. Explain.
  5. Discuss the characteristics of embryonic fields.
  6. Dissociated embryonic cells reassociate according to type. Explain and relate to cell movements in embryos.
  7. Describe events leading to axiation in the frog embryo (dorsal- ventral, anterior-posterior, medio-lateral).
  8. 1. What can eye and heart field development tell us about fields in general?
  9. 3. When the distal half of a paddle stage limb bud is removed, the pro ximal part of the limb, only, is formed. Explain.
MULTIPLE CHOICE 26. What cannot be determined by limb transplants? a. time of axis determination b. capacity for regeneration c. function of apical ridge d. polar coordinates e. none of the above. TRUE-FALSE 3. Embryonic fields can be cut into a limited number of pieces like a magnet and still all the pieces retain polarity and ability to produce an organ. Mosaic eggs have set patterns of development and cannot regulate. 11. Fields in early embryos represent determined regions which cannot be altered by removing them or by inhibiting movement or fusion. Regulative eggs give rise to mosaic embryos at some time in development. Gradients in unfertilized eggs may help to determine some of the embryonic axes.

LIMB PATTERN DEVELOPMENT

1. How can transplantation experiments show when limb or other field axes are set? 2. What is the importance of the zone of polarizing activity? What is the effect of adding an extra ZPA to a limb? 3. What is the polar coordinate model? What is the shortest intercalation rule? Explain why some experiments produce duplications and some produce intercalations.

SYNAPTIC SPECIFICITY

1. What is NGF and how does it have an effect? 2. What factors are involved in ventral retina cells sticking to dorsal tectal cells and vice-versa? 3. How is the visual cortex involved in vision, and how do the proper synapses get made? How does electrical stimulation at the synapse control development?

CELL DEATH IN DEVELOPMENT

1. How is cell death in the nervous system and limb controled and how is it important in development?

SEX DETERMINATION

1. What is the genetic basis of sex determination? Discuss sex chromosomes and autosomes. 2. How are hormones and receptors important in control of sex development? Explain the differences between male and female gonad and duct and external genitalia development.

HORMONES AND RECEPTORS

FILL-IN: -----2. Hormone causing metamorphosis in amphibians. --- 3. Location of steroid hormone receptors ---4. Second messenger involved in germinal vesicle breakdown. ESSAY: 3. Present evidence that some differentiation depends on hormones. Distinguish between developmental effects shown for steroid hormones and peptide hormones. Organ cultures of ovaries or testes with either the male or female urogenital ducts produce different results in the gonadal and urinary ducts. Explain. Discuss the hormone control of the menstrual cycle. Discuss the hormonal control of gametogenesis, for both sexes. How can different cells react differently to the same stimulus (morphogen, growth factor, or other chemical)? How can cell surface structures control embryo cell growth, adhesion and motility? What kinds of signal transduction across the cell membrane are important in developmental events?

GENERAL

1. What is wrong with the statement "ontogeny recapitulates phylogeny"? How can alteration of early acting developmental genes lead to evolution? 2. What are cytoplasmic determinants and where do they come from? How are they localized and what happens during cleavage? What is the difference between early and late genes expression in development? What kinds of stimuli are necessary in order to utilize determinants or start transcription of previously inactive genes? 3. Discuss how the presumptive germ layers may be already laid out in the early embryo by materials they contain which are different from each other. Why is there a difference in the potency of the same germ layer cells? If they are already different, how can ectoderm be totipotent at early gastrula? 4. What is the difference between having stored information for certain functions and being able to respond to inductions of different sorts? How are extracellular materials important in development? 5. Knowing what you know now, what do you think causes the decrease in potency of nuclei in the nuclear transplant experiments? TO STUDY THE REST OF THE BOOK: ASK YOURSELF THIS ABOUT EACH CHAPTER TITLE:(SUBHEADINGS MAY BE THE EXPERIMENTAL PROOFS) 1. Do I know the mechanism of this? What kind of cell machinery is involved? 2. Do I know the stimulus for this? Is this a temporary process or a longer term genetic process? 3. What is the genetic basis of it? Is there a certain group of genes which must be activated or inactivated? 4. Is there a pattern which must be laid down for this to happen, and what causes it?