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

360
I sutlt'lARY ANp coNcLUsto]s
1. The slmple pþysical procedure of wîndowlng.e.ggs at early stages of
lncubatlon (with removal of 2 ml . of albumen) proved to be highly teratogen
I c.
2. Wlndowing at 14 hours caused a very high earìy mortal ¡ty, w¡th severe
malformations ln the survlvlng embryos. fr."ar"na at 26 hours produced a
lower nprtal lty, wlth a hÍgh incidence of defects (predominantly involving
the nervous system). Exposure at 38 hours was much less teratogen¡c.
3. Remova I of the lntroduced alr space, by reexpansion of the aír-cell
or by the.addltlon of albumen or F 12 medlum, almost abol ished the teratogenlc
effect of windowing, îf pêrformed immediately.
4. The lncidence of malformations produced by windowing at 26-30 hours
increased with extended periods of incubation. Open brain and cord defects,
nlcrocephaly, eye defects and trunk and rump cysts were present by 3 days.
Facial defects and rumplessness appeared by ! days, but ectopia viscerum
and limb defects were not promingnt unt¡l after 5 days.
5. Examination of skeletal defects at 12 dêys showed that vertebral
lesions varîed ín severity according to the region. Spina bifida occulta
occurred largely in the cervical and upper thoracic regions. Spina bifida
manifesta was seen between the lower thorac¡c and sacral regions. Vertebral
irregularities and deletíons were almost confined to the caudal region.
6. open braln defects occurred at every Stage after the expected closure
of the anterior neuropore, suggesting that they arose by non-closure.
7. open cord defects were of two distinct types.
8. Hyeloschlsis was preceded by a characteristic triå.ngular shape of
the rhombold sînus. Serial sectlons revealed regular open defects, wlth