. Bonner zoologische Monographien. Zoology. 42 300 200 100 3 5 7 9 11 1 3 months Fig. 26: Seasonal changes of endocrine glands (volumes of nuclei) in bats (Myotis myotis, Rhinolophus hipposideros). Adapted from Dörfler (1971). Am = adrenal medulla, Zf = zona fasciculata, P = parathyroid, IL = islets of Langerhans, T ="â thyroid. C-cells of the thyroid: The parafollicular C-cells contain calcitonin and serotonin. During hibernation they are inactive and store the hormones (Dörfler 1971, Nunez and Gershon 1972). During aestivation the number of the cells is increased. In marmots an annual
. Bonner zoologische Monographien. Zoology. 42 300 200 100 3 5 7 9 11 1 3 months Fig. 26: Seasonal changes of endocrine glands (volumes of nuclei) in bats (Myotis myotis, Rhinolophus hipposideros). Adapted from Dörfler (1971). Am = adrenal medulla, Zf = zona fasciculata, P = parathyroid, IL = islets of Langerhans, T ="â thyroid. C-cells of the thyroid: The parafollicular C-cells contain calcitonin and serotonin. During hibernation they are inactive and store the hormones (Dörfler 1971, Nunez and Gershon 1972). During aestivation the number of the cells is increased. In marmots an annual cycle has not been proved clearly. The lack of calcitonin could contribute to hypercalcemia and hypermagnesemia during hibernation (Stoeckel et al. 1967). Parathyroid: Histological studies have shown a prehibernatory activity of the gland. Studies of Ca-metabolism seem to confirm this. The annual cycle of parathyroid activity is inverse to the rhythm of the gonads (Kayser 1961), but identical with the C-cell activity (Dörfler 1971). Pancreas: Based on earlier studies of Suomalainen and his co-workers (1955), it was concluded that insulin plays a major role in inducing hibernation. More recently, this has been questioned (Laurila and Suoma- lainen 1974, Popovic 1960). The histological evidence of an activation of beta-cells is probably related to the autumnal storage of glycogen and fatâbut not directly to the torpor. During hibernation there is no activity in beta-cells (Kayser 1961, Smit-Vis and Smit 1966). But such activity appears at the end of the hibernation season, as well as during arousal (Laurila and Suomalainen 1974, Portius and Raths 1957) and during cold stress in awake hibernators subjected to artificial hypothermia (Weber and Scheufler 1970). Insulin is stored during hibernation (Gabe et al. 1964,. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of thes
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