Lens deviations in rabbit offspring after short-term prenatal exposure to dexamethasone: a light-microscopic study.

Female New Zealand White rabbits were treated subcutaneously with 0.0375 or 0.15 mg kg-1 dexamethasone or physiological saline solution from the 8th through to the 11th day of gestation. Short-term administration of 0.15 mg kg-1 dexamethasone induced two types of morphological lens deviations in the offspring (lenses were studied by means of sagittal serial sections). In the first type of deviation a progressive series of changes in the lens bow region was observed. Early changes consisted of an enlargement of some lens bow nuclei, an increase in the number of lens bow nuclei and a disturbance in the shape of the lens bow. Later changes consisted of the degeneration and vacuolization of a peripheral zone of cortex fibre cells. The overall picture showed that the size of up to 8% of the nuclei in the deviating lens bows was enlarged and that the average number of lens bow nuclei in the deviating lenses was 28% higher (P less than 0.01) than in the lens bows without deviations. The second type of lens deviation consisted of isolated bundles of disintegrated cortex fibre cells, which extend downwards (anterior-posterior) from subepithelial vesicles. In these bundles all nuclei were smaller and more basophilic than normally. Both types of lens deviations occurred independently in the superficial cortex. Control offspring treated with physiological saline solution showed neither the first nor the second type of lens deviation. Of the offspring exposed to 0.0375 mg kg-1 dexamethasone one animal (8%) showed lens changes of the first type only, whereas 59% of the offspring exposed to 0.15 mg kg-1 dexamethasone displayed either one or both types of lens deviations.