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

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4. r sELEcr I oN !F EGGq
4.1,1 . lricub¿it i on
Experlmental and controì .eggs were rout¡nely cul tured from the
beglnning of lncubation at 37.54C and 60? humidlty, lying on thelr
sldes wlth the long axls horizontal.
At 26 hours of incubatlon (al lowlng one extra hour for rewarmìng
after remova l from the refrígerator) candl ing "ras perfo¡:med în the dark,
by layîng each egg horizontal ly over a 4 cm. x 3 cm. lîght-source and
marking the shell with a penci I at the site of the embryo
\ .1 .2 Cand I ïng
Ëmbryos were graded (accordlng to an êrbitrêry scale determined
by previous experience) ¡nto three sizes -small, medium and largewhîle
infertile eggs were rejected. ln this study only the eggs with
medlum-sized embryos were used. Eggs with large-sized embryos were
rejected, while those wîth smal l-sized embryos wåre al lowed to deveìop
for a further two to four hours and then used only if they had reached
medium size.
\.2 TECHNtq 0F_Q!!¡r!NG ANp cl0stNq EGGS
4.2,1 PreliminqllExperiments
ln ê ser¡es of prel iminary experiments, attempts were,made to produce
open defects of the central nervous system by the use of several proven
teratogenic agents introduced through a shall window. These experiments"
however that the well-known technic of openíng a wíndow in the
"showed
shel I above the embryo and removing 1 - 2ml . of albumen (to prevent adheslon
of the embryo to the cut edges of shell),was in itself highly
teratogenic at early stages of avian development. lllndowed but otherwise