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

261
ln these tables the contrors and the experimentar embryos w¡thout
neural dèfects show extensive separation between somites and neural
material; there Issome separation between notochord and neural material
by Stêge 20 in two embryos ('ZC Zl , 428 73). The embryos wìth neural
defects also show extensive separat¡on from somites, with separation
from notochord (especially ln myelosct isis after Stage ,t7) ¡and somite
defects (especial ly ín myelodysptasia after Stage l6). There is no
close association between the rength of ectoderm discontinuíty from
neural tissue and the type of neural tesion
.
Figsi. 112-119 compare the percentage lengths of neural defects in
regions B,c, D and E of each âffected experimental embryo with the correspondîng
percentage I engths of:
(a) ectoderm d iscont inu ity
(b) somite separation from neural tîssue
(c) notochord separation from neural tissue
(d) local somi te defects.
These figures demonstrate the percentage distribution in the four
regions of embryonic cord of myeloschisis irom Stage lJ and myelodysplasia
from Stage 16. Horvever as region B is much larger than all the other
regîons the size of each region in relation to a whole embryo is disproportionate.
The assocîation of myeloschisis with notochord sãparation
after Stage 1/,and of myelodysplasia with somite defects after Stage l6
are clearly i I lustrated.
.An analysis of variance could not be performed with these figures
as so many of the histologîcar features showed zero varues in both
exper imenta I and control embryos.