Cleavage & Gastrulation

Edit Answers
12345678910111213141516171819202122
Across
  1. 2. ball of cells produced by cleavage
  2. 4. acronym for mitosis-promoting-factor, major factor in regulation of early blastomere cell cycles
  3. 7. eggs with only a small area of the egg that is free of yolk (eg: bird and fish eggs)
  4. 10. splitting of a single cellular sheet into two parallel sheets – results in a second new epithelial sheet of cells (eg: mammal hypoblast formation)
  5. 12. __________ cleavage: complete/total cleavage, includes isolecithal and mesolecithal cleavage
  6. 14. larger subunit of mitosis-promoting-factor, regulates the smaller subunit and controls MPF
  7. 17. migration of the embryo’s surface cells to the interior (individual cells are able to move independently from one another)
  8. 18. pole high in yolk concentration
  9. 19. __________ cleavage: when cell divisions only happen in a small disc of cytoplasm free of yolk
  10. 20. acronym for mid-blastula transition, changes include 1) introduction of gap stages G1 and G2 2) cell division synchronicity is lost – cells “go their own way” 3) new mRNAs are transcribed from zygotic genome
  11. 21. inward movement of an expanding outer layer, the cells of this layer spread over the internal surface of the remaining external cells (eg: amphibian mesoderm)
  12. 22. eggs with a yolk in the center (eg: insect eggs)
Down
  1. 1. eggs with sparse and equally distributed yolk
  2. 3. when epithelial sheets move as a unit (not individually) and enclose the deeper layers of an embryo (multiple mechanisms, including cell division, cells changing shape, or layers of cells radially moving)
  3. 5. pole low in yolk concentration
  4. 6. __________ cleavage: incomplete cleavage, includes telolecithal and centrolecithal cleavage
  5. 8. _________ furrow: the indentation that expands and ultimately splits the cell
  6. 9. process through which the “body plan” of the organism is established from the three germ layers (endoderm, mesoderm, and ectoderm)
  7. 11. amount and distribution determines where cleavage can occur and the relative size of blastomeres
  8. 13. localized infolding of a sheet of cells (epithelium) without cells losing their tight adhesive connections
  9. 14. acronym for cyclin-dependent kinase, smaller subunit of MPF that regulates mitosis through phosphorylation
  10. 15. ____________ extension: when lateral cells from all germ layers move towards the midline, leading to convergence of these cells. A way for the embryo to grow and extend along its axis.
  11. 16. _________ cleavage: occurs around the periphery of a cell, divisions only happening in the rim of the cytoplasm