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

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\,\.3 Effect of Artìficial Aìr S
The role played by the artificîal air space was thus further examined
by either restoratîon of the originâl stête of the eggs, or by modifications
of the external envíronment of unwindowed eggs during incubatîon.
Experiments designed to avoid exposure of the developing embryo
to the air space took two forms. After closure of the window with ê 3 cm,
circle of parafilm and a squaqe of elastoplast, a second 5 mm. x 5 mm,
window was made near the pointed end of the egg. ln some cases the egg vJas
fll ted with F, culture medíum (Ham, 1!6!),
cr with ålbumen from '
an egg of the same developmental age (fig, Bn ¿ s) .
Alternatîvely the introduced air was removed by re-expansion of the
collapsed air cell (with air from a rubber bal loon) before seal ing the
second window. (Pig. 9n a g) .
4.5 BACTERIOLoGIcAL CULTURE
The sterility of the operative techn¡c was assessed by making
bacteriological cul tures of albumen on bldod-agar plates at the time of
wîndowîng and at fixation of the embryos.
\.6 ExAMtNAT|oN oF EARLY EMBRyQ!
4.6.1 Fi xat ïon and Stagíng
,^oñto-;ãr,
embryos recovered 0 tq 4z.hours afrer windowins
were washed in Howardrs salÍne, fixed in Bouints fluid, and bleached in 702
alcohol contaíning 22 ammonia solution. Curl ing during fixatlon was prevented
by includîng a square of filter paper in the dish above the embryo.
For full details of the method see Appendíx A.
After bìeaching, all the embryos were examined for defects and Staged
(Hamburger and Hanilton, t95t)'. To Preserve a permênent record. before