Cytological studies of the pineal in relation to the annual cycles in the testis and climatological variables of free‐living roseringed parakeets(Psittacula krameri)

Comparative view of pineal gland morphology of nocturnal and diurnal birds of tropical origin

“…We observed great variation in pinealocyte architecture of nocturnal and diurnal birds. It has been reported that avian pinealocyte under natural environmental and experimental conditions undergo changes (in number of follicles, height of cells lining the follicle, and diameter of the parenchymatous cells in the solid region) in an inverse manner with regard to the function of the testis during the seasonal cycle (Chaudhuri and Maiti, 1989;Haldar, 1990: Maitra andDey, 1993). Conceivably, the pineal cytology of avian groups might have responded to environmental factors, especially light, and in turn also gonadal steroids and maybe melatonin itself (Maitra and Dey, 1995).…”

Effects of Photoperiod Alterations on Adrenocortical, Pineal and Gonadal Activity in Nocturnal bird, Athene brama and Diurnal bird, Perdicula asiatica

“…The importance of environmental factors such as photoperiod, temperature, rainfall, humidity and consequently food availabilty, in the control of annual reproductive cycle (Sakai and Ishii, 1986;Gwinner, 1989;Meijer, 1989;Cockrem, 1995) and role of pineal gland in this regard is suggested in avian species (Ralph, 1981;Vivien-Roels, 1985;Glass, 1988;Haldar and Ghosh, 1990;Chakraborty, 1993;Maitra and Dey, 1993). It has been suggested that the pineal gland may be one of the photo-neuroendocrine transducer to convey photic information via the daily pattern of melatonin secretion and whose primary effect is related to the suppression of the reproductive system (Arendt, 1988).…”