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Friday, May 23, 2008

Embryo Ectoderm

How high yield is Embryo??? Well I think most of it can be quickly memorized right before the exam but here are some of the key structures and where they originated from:
You must know the 3 basic types of origination:
Ectoderm, Mesoderm and Endoderm
Here is some ectoderm to think about!

In Ectoderm you have sub classes Surface Ectoderm, Neuroectoderm and Neural Crest
Surface Ectoderm:
Epidermis
Hair
Nails
Inner Ear, External Ear 
Enamel of teeth
Lens of eye
Anterior Pituitary (Rathke Pouch)
Parotid Gland

Neuroectoderm:
Neural tube
CNS
Retina and optic nerve
Pineal Gland
Neurohypophysis
Astrocytes 
Oligodendrocytes
Neural Crest:
Adrenal Medulla
Ganglia:
Sensory and Autonomic
Pigment Cells
Schwann Cells
Meninges
Pia and arachnoid mater
Pharyngeal Arch Cartilage
Odontoblasts
Parafollicular (C) cells
Aorticopulmonary Septum
Endocardial Cushions

They like to trick you up on the neural crest cells. SO they may ask you about a sick infant and give all the symptoms of Hirschprungs / megacolon and than ask you something like. "the cells involved in this disease come from the same origin of which of the following?" then they list a bunch of garbage. In the mean time your still trying to figure out what is wrong with the kid! Well he is missing cells that run his enteric nervous system of his gut. Those cells have a neural crest origin like all ganglia. So in the answer choices you want to find something that also originates from neural crest cells, like dental pulp = odontoblasts.


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