Notes From The first part of Chapter 1 from "Principles of Development" by Lewis Wolpert and Cheryll Tickle:
Developmental Biology Notes
I. Big Question: how does a single-cell (fertilized egg) become a multi-cellular organism?
a. Which genes are express- when? Where?
b. How do cells communicate?
c. How is developmental fate determined?
d. How do cells proliferate/differentiate?
e. How are big changes in body shape made?
II. Important Definitions
a. Stem cells- ability to proliferate and develop in to different tissues
b. Cancer cells- ability to divide indefinitely
c. Embryogenesis- fertilized egg to embryo
d. Morphogenesis- development of form
i. Animal pole- pigmented upper surface of unfertilized egg
ii. Vegetal pole- lower region with accumulation of yolk granules.
iii. Cleavage- mitotic divisions where cells do not grow between each division, cells become smaller
iv. Blastula- after 12 divisions
v. Germ layers
1. Animal region gives rise to ectoderm (skin/nervous system)
2. Mesoderm, Endoderm: internal organs
vi. Gastrulation: endoderm & mesoderm move inside, body plan established
III. Origins of Developmental Biology
a. Germ cells vs. somatic cells
b. Fertilization results in the zygote
c. Meiosis produces germ cells
d. Mitosis produces somatic cells
IV. Two main types of development propsed
a. Weismann- "determinants" distributed unequally to daughter cells and so would control the cells' future development- "Mosaic mechanisms"
b. Driesch- "regulation" ability of an embryo to restore normal development even though some proportions removed/altered early in dev.
V. Cell Communication
a. Induction- one cell/tissue directs the development of another neighboring cell/tissue
b. Blastopore- slit-like invagination formed with gastrulation begins
c. Spemann-Mangold Organizer