Disorders in the development of the crystalline lens in chick embryos following exposure to insulin]

Inection of insulin into the chicken egg-white in dosage of 4 i. u. during the 1st - 14th days of incubation results in degenerative changes in the lens. Injection of insulin during the 1st day of incubation (before the beginning of eye differentiation) fails to prevent development of the eye vesicle and determination of the lens. The morphogenesis of the lens goes normally up to the 10-13th days of incubation. From this moment abrupt degenerative alterations make their appearance as well as destruction of the lens fibres. When the lens is affected by insulin the destruction is observed on the following day. The mechanism of insulin effects upon the lens seems to be as follows: Exogeneous insulin remains in the embryo tissues for along time. When the tissues are preparing to accept endogeneous insulin and become susceptible to it (the 10th-11th days of incubation) exogeneous insulin begins its pathological influence on the lens fibres. After the 13th-14th days of incubation endogeneous insulin comes into the blood. Against the background of exogeneous insulin it results in excessive increase of concentration of insulin in the embryo tissues and great degenerative changes in the lens.