The Effects of the Presence or Absence of the Pituitary Gland on the Daily Rhythmicity of Mitotic Rates in Urodele Larval Tissues
When bihourly determinations are made of the mitotic rates of a number of urodele larval tissues, a rhythmic pattern over the 24-hour period manifests itself. Periodicity has been described for the mitotic rates of larval epidermis (Scheving, Chiakulas and Abzug, 1959), gastric mucosal epithelium (Chiakulas and Scheving, 1961), corneal epithelium (Scheving and Chiakulas, 1962) and the hemopoietic tissue of the cortical zone of the liver (Chiakulas and Scheving, 1964). In all the tissues investigated, a bimodal pattern of rhythmicity has been found, with one peak in the rate of cell division occurring during the hours of light and another peak during the hours of darkness. The original study on epidermis and the subsequent ones on gastric mucosal epithelium and the hemopoietic tissue of the liver, compared the mitotic rates in these tissues of larvae collected at 2-hour intervals from the natural pond environment to the rates found in the tissues of laboratory-reared animals. In both pond-reared and laboratory-reared larvae, a basic bimodal rhythmic pattern of the mitotic rates is found with only minor differences in the timing of the peak and trough values, although a considerable difference in the magnitude of mitotic rates of the tissues occurs between the two groups.
KeywordsLime Peri Adrenalin Hematoxylin Nism
Unable to display preview. Download preview PDF.
- Bullough, W. S., and E. B. Laurence: Stress and adrenaline in relation to the diurnal cycle of epidermal mitotic activity in adult male mice. Proc. roy. Soc. B 154, 540–556 (1961).Google Scholar
- Halberg, F., E. Halberg, C. P. Barnum, and J. J. Bittner: Physiological 24-hour periodicity in human beings and mice, the lighting regimen and daily routine. In Photoperiodism and related phenomena in plants and animals, Withrow, R. B., Ed., A.A.A.S., Washington, D. C., 803–878 (1959).Google Scholar
- Scheving, L. E., and J. J. Pauly: Effect of adrenalectomy, adrenal medullectomy and hypophysectomy on the daily mitotic rhythm in the corneal epithelium of the rat. This symposium.Google Scholar
- Zander, H. A. J., J. Waerhaug, and F. Halberg: Effect of hypophysectomy upon cyclic mitotic activity in the retromolar mucosa of rats. J. clin. Endocr. 14, 829 (1954).Google Scholar