Abstract
Summary
Cell size is smaller and mitotic rate and DNA content of parotid glands of rats maintained on liquid diet (Metrecal) from weaning on are lower than those of litter mates maintained on chow. At 32 days of age, when mitotic rate is 4 per 1000 acinar cells in parotid of chow-fed rats, it is nearly zero in the Metrecal rats. Substitution of a solid for liquid diet at 32 days brings about a marked increase in mitotic acitvity and DNA content, and increase in cell size, that are evident with 24 hr. The change is most marked at 1 day with regard to cell size, 2 days for mitotic rate (60 per 1000 acinar cells) and 5 days for DNA. Removal of the postganglionic innervation prevents the increase in mitosis and DNA that occurs with introduction of solid food. Neurally-mediated normal phisiological activity of the gland apparently evokes the excessive mitotic activity.
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