EMBRYOLOGY Life Sciences 2 September 3, 2010
LS2 running group SUNDAY MORNING 10:00 Weeks Bridge ALL LEVELS WELCOME ESPECIALLY NON-RUNNERS (YET)!
THIS LECTURE MAIN POINTS: 2. What is the basic body plan? 1. How do we go from a single cell to awhole body?
1. Embryology helps explains why and how body gets its shape 1. The body is largely a set of folding tubes and sheets , each of which derives from three initial layers of cells 2. The body’s many parts fit and work together because of how they grow: a hierarchical (branching) process with many interactions between units
2. Embryology helps explain mechanisms by which evolution creates new forms, including humans Basic answer: we are essentially fish, which, in turn, are just evolved worms (NEXT LECTURE)
1. First stages of life 2. Formation of major cell lines 3. Formation of basic body plan Neural tube Central axis Gut tube and body cavity Outline
The Beginning Part 1
We begin, of course, as a single cell: the zygote Human body: ! 350 different kinds of cells, each with: membrane cytoplasm nucleus All cells have four basic functions: multiplication movement change character (differentiate) signal to other cells
Zygotes derive from two gamete cells sperm 2x (diploid) 4x 4x 2x 1x 2x 1x x x Meiosis I Meiosis II Spermatogenesis Oogenesis egg 1x (haploid)
Fertilized zygote Pronuclei (n=2) 1. Fertilization: 12-24 hours after ovulation 2. One-cell stage: two pronuclei fuse (zygote) 3. First cleavage : two-cell stage ! 30 hours post ovulation
2 cell stage
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- Fall '10
- Developmental Biology, Neural tube, Mesoderm