Universlty of Manitoba, ln Partîal Fulfiìlment - MSpace at the ...

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lmnediately after closure, separation of neural crest tissue was
apparent: Cránially the. rhombîc roof was seen to be closing at Stage lO,
and thìckened by Stage 10. Caudal ly there were no âccessory neural canals,
and no other signs of an overlap zone. Differentiation of neural tissue
from ectoderm was alreâdy apparent, though the ectoderm was cont¡nuous
w¡th the neural folds at unclosed areas and ¡n contact v,r¡th the neural
tube at closed areas.
The notochord was ln close contact with neural tissue from the future
midbraln down to the protonobchord. Somitic mesoderm was general ly in .. ":
contact with neural t¡ssue at the level of the somites, but not in the areas
of unsegmented and fused mesoderm at the rhomboid sinus. The somìtes were
all well formed, with no evidence of reduced volume and no cyst¡c or
hemorrhag i c changes .
The prîmitive streak and Hensenrs node were prominent, with no formation
of a ta¡l-bud at thîs Stage.
63,2 Stage l0 Experimental Embryos (Gtoup l)
The histologícal appearances of these embryos were similar to those of
Stage 10 control s for:
a) neural cJosure
b) neural foldins
c) formatîon of neural crest
d) development of the rhombic roof
e) absence of an overlap zone
f) continulty of neural folds with ectoderm
S) close contact of notochord with neural tissue
h) contact of somites with neural tïssue
î) no cyst¡c or hemorrhagic changes