Electron micrographs of resting and pilocarpine-stimulated acinar cells of mouse submaxillary glands revealed the majority of mitochondria in close association with lateral and basal portions of the acinar cell membranes. The qualitative observations were confirmed by quantitation. Speculations as to the functional significance of this observation are discussed.
The present study reports on the effects of in vivo single and multiple isoproterenol (ISP) injections on the proliferative response of subsequently explanted mouse submandibular glands. Explants were cultured in Waymouth’s medium supplemented with 10% fetal bovine serum, and were harvested after 1 2,4 or 6 days in culture. 24 h prior to harvest, the explants were fed medium containing [3H] thymidine. At the time of harvest, the explants were fixed in situ and processed for light-microscopic radioautography. The number of labeled nuclei and the total number of nuclei were counted, and labeling indices were calculated for the control and ISP-treated explant sections. The results show that the ISP-treated explants had more cells actively synthesizing DNA than did the corresponding control explants after 1 day in culture. In addition, after 2 days in culture, the explants from mice that had received a single dose of ISP incorporated more [3H] thymidine than the corresponding control explants. These results suggest that the in vivo ISP stimulus initiated a hyperplastic response in vivo that was completed during the 1 st or 2nd day in vitro.
The purpose of this investigation was to measure quantitatively nuclear volumes in outer fasciculata cells in adrenal glands of rats subjected to chronic stimulation of steroido-genesis by ACTH, or to chronic inhibition of functional activity by hypophysectomy or by injection of the steroidogenic inhibitors, U-8113 (p-aminophenyl butanone) and SU-4885 (metopirone). Nuclear volumes, after a recovery period from those effects, were also measured. Chronic daily administrations of ACTH for 7, 14, and 30 days led to a progressive, statistically significant increase in nuclear volumes of fasciculata cells. These changes were found to have been reversed 14 days after discontinuation of hormone treatment. Hypophysectomy resulted in a significant decrease in nuclear volumes. The steroidogenic inhibitors SU-4885 and U-8113 had a biphasic effect on the nuclear volumes with an early decrease and subsequent increase to normal values. Since a decrease in nuclear volumes in the adrenal glands of inhibitor-treated subjects occurred in the presence of cellular hypertrophy and a significant increase in adrenal weights, it is concluded that changes in nuclear volumes can be positively correlated with the secretory activity of the cell rather than with the sizes of cells or glands.
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