[The development and structure of the optic nerve in normal embryos and fetuses of the white rat and after x-ray irradiation]. 
With the aim to reveal the ionising radiation effect to formation and structure of the optic nerve (ON), 55 white rat intact embryos and fetuses and 77 experimental embryos and fetuses, subjected to x-ray irradiation on the 10th-14th day of development, have been studied.  The main regularities in formation of the ON have been stated under normal conditions.  Certain disturbances in formation of the ON and in the internal membrane of the optic vesicle (future retina) under effect of x-rays in the dose of 2.24 Gy have been detected during the intrauterine period of development--folds, rosellas of retina, retardation in differentiation of the retina nervous layer, aberration of the ON growth with a subsequent reduction, the ON hypo- and aplasia, retardation in formation of neural sheaths, absence of intraspace between the sheaths.