Effect of puromycin on the ultrastructure of keratohyalin granules

Keratohyalin granules (KHG) from control and puromycin-treated hamster cheek pouch epithelium were studied by electron microscopy. The animals were killed 1-4 hours after injection with 75-100 microgram puromycin per gram body weight; controls were injected with saline. The KHG from control animals were round or oval and consisted of a finely granular background matrix containing many small, round, homogeneous electron-dense deposits. The KHG from puromycin-treated animals showed marked variation in morphology and size. They consisted of a coarse granular or speckled matrix and round, club-shaped or comma-shaped electron-dense deposits. Since puromycin is known to inhibit protein synthesis, alterations in KHG structure support previous reports suggesting the protein nature of KHG.