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Chapter 47: Animal Development

Embryonic Development
considered the moment the sperm enters the egg's surface
Acrosomal Reaction
the moment the sperm nucleus reaches the egg, releases a hydrolitic enzyme that digests the material around the egg; stops new sperm from entering; "Corticol reaction" triggered by Ca2+
Fertilization Envelope
a membrane that blocks multiple sperm from entering the egg; increase in Ca2+ also rises protein development
Development Factors
the genome within a zygote directs cellular development
the process by which an animal takes shape: cells > tissue > organs
the process by which embryonic cells develop into specific cell types
Steps of Development
Produces many cells
Path of Differentiation
"Any cell" to specialized versions
Frog Cloning Experiment
would different cells contain the whole genome, or would certain changes in the genome happen in different cells? Results dertemined that when a nucleus from any cell is transported into an egg, development will occur to some degree.
Key Finding from Frog Experiment
Nuclei DO lose developmental potency into adult cells as they differentiate -- changes occur in the genome; HOWEVER, nuclei from adult cells CAN support development -- the changes are reversible
Key Finding from Frog Experiment
Differnces in adult cell types result from different genes being turned on and off: TRANSCRIPTIONAL CONTROL
Frog Cloning
Different stage cells could still produce offspring; albeit at less successful rates
Gray crescent
where sperm enters the egg; zygote rotates 30 degrees
Tool nuclei from adult cell; implanted the nucleus into an embryonic egg cell, implanted the egg in surrogate -- new dolly clone
Three Stages of Development
Mitosis -- cell division; Patterning -- cells arranged in position, body plan is established; Differentiation, cells become different and acquire function
the process in which one large cell (the egg) gets divided into blastomeres -- many many cells without growth before differntiation can occur
Polarity in Eggs
the body axis depends on the polairty of the egg -- yolk is the vegetal pole; animal pole has the least
Polarity in Egg Development
Body Axises
the direction of which way the body will form; cytoplasm and protein will push the egg in one way or another
Early Stages of Development
the movement of the blastula which folds inward, now there are three layers, ecto (outer), endo (digestive), meso (muscles and blood)
outer cells of the blastocyst that secrete enzymes that allow implantation
the fluid-filled cavity inside a blastula
Convergent Extension
once morphogensis starts to happen (shape changes), the layers get formed, the cells become long and narrow, underoing shape changes
Key Functions of Ectoderm
Key Functions of Mesoderm
Key Functions of Endoderm
when the regions of the embryoninic germ cell begin to develop into organs
How do Neuorns get Made
the ectoderm starts to fold in and differentiante, becoming spinal cord, nerves, etc and eventually the brain
Induction and Signaling
once the cells and organs begin to form, the potency decreases; the cell fate is determined by inductive signaling
Spemann Organizer
dorsal lip of cells of blastopore and their derivatives (notochord and head endomesoderm). establishes the basic body plan of the early embryo; a graft can induce development of a WHOLE embryo
ability to convey posterior positional information; a graft can induce patterns (Zone of polarizing activity)
Apicial Ecotdermal Ridge; help initiate growth in limbs and buds "sonic the hedgehog" can induce growh, tells tissue where to differentiate
Neuronal Formation
remember, the notochord (spinal cord, support axiss) forms from the mesoderm and the neural plate (thickened plate in the ectoderm)
Dorsal Lip
the region in which gastrulation starts, where the cells will ultimately form the mesoderm and notochord