OUTLINE OF FIRST LECTURE: Jan 10, 2007
Embryology Biology 441 Spring 2007 Albert Harris
Basics of EmbryologyEmbryology (~= "Developmental Biology" )
Genetics -> -> -> -> -> -> -> -> -> -> -> -> -> -> -> -> -> -> -> -> Anatomy
DNA base pair sequences
What are some of the most important processes that cause embryonic development?
Protein synthesis (of course!)
Cell Differentiation (selective transcription of certain subsets of genes)
The human body is made of about 250 differentiated cell types
(the following are random specific examples of what is meant by a differentiated cell type
cardiac muscle cells are another example of a differentiated cell type
B-lymphocytes are another example....etc.
the blue-sensitive cone cells in the retina of your eye count as one cell type
the green-sensitive cone cells in your retina counts as another cell type
so do the red-sensitive cone cells in your retina
so do the "ganglion cells ", whose axons connect the retina to the brain
"pigmented retina epithelial cells " are another cell type,
not to be confused with the "mesenchymal pigment cells" in your skin
because they are an entirely different cell type
1) Special proteins that bind to DNA and control gene transcription = "Transcription factors"
2) Extracellular proteins that signal cells what differentiated cell type to differentiate into.
In addition to factors that control cell differentiation according to location in the embryo, what else determines the anatomical locations of differentiated cell types?
a) Acto-myosin contractions along one surface of cells or sheets of cells,
b) Locomotion of cells from one part of the body to another (one part of an embryo to another)
c) Exertion of traction forces , that pull other materials past cell surfaces.
What about growth? Does the enlargement of cells exert forces that create anatomical structures?
This is perhaps somewhat strange, because so much growth occurs in many embryos. You would expect that growth would produce some pressure, and that this pressure would be put to use building structures, or changing arrangements of cells. But every case that has been carefully studied turned out to be driven by some different force.
back to syllabus
back to index page