Teratogenic effect of windowing eggs at early stages of avian development

The chick embryo is widely used as an experimental model for embryological and teratological studies. Treatment may be iether across the intact shell or through a window cut in the shell above the embryo. However, it is apparent from the present investigation that merely windowing eggs at early stages of development is highly teratogenic. Abnormal development can be attributed to the presence of an introduced air space above the early embryo. Obliteration of this artificial air space by three different methods significantly reduced the teratogenic response.