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

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3.1 THE CHTCK EMBRYo
The chlck embryo was se¡ected as the expêrimental model in the
present study for the fol lowîng reasons (Hatthews et al., 1974):
a) fertile eggs êre cheap and avaìlable throughout the yeâr
b) avian embryology has a long history añd.an extensive I iterature,
with a well defined system of Staging based on simple morphological
criteria (Hamburger and Hamilton, 1951)
c) the developing chick embryo is more readily accessible than the
mammalîan embryo to dìrect observation and manipulatîon th.rough
a window in the shell (though thìs has certaîn concomitant disadvantages)
d) whole embryos as well as ísolated fragments can be cul tured in oityo
or 4n uiuo, with direct observation of the embryo by either technic.
Despîte the advantages offered by the varÍous in oitro techirics, an
in oi¡to (in ouo) method was finally chosen because:
a) it provided a method of producing open neural defects by the use of
a simple physical procedure
b) it allowed prolonged culture of embryos with various congenîtal malformations
to advanced stages of developmeni.
3.2 souRcE oF Ëqq ¿N!__!xlrjBiqll0N
The eggs used for this work were obtained from a second generation
hybrid tfhite Leghorn flock c.ontainíng one colored and three pure Leghorn
línes, maintained by the Department of Animal Science of the Uníversity
of I'lanítoba. The incidence of spontaneous malfornrations in this flock
cannot be establ îshed because of the reluctance of the oríginal commerc!at
suppl iers of the stock to supply appropriate information.