Intranuclear inclusions in the pituitary gland of cynomolgus monkeys.

In a 3-month oral toxicity study of a pharmaceutical agent, intranuclear inclusions were seen in the secretory cells of the pars anterior of the pituitary gland of 22 of 40 cynomolgus monkeys, with similar incidences in control and dosed groups. All monkeys were clinically healthy. Electron microscopic examination revealed that the intranuclear inclusions were cytoplasmic invaginations.