Anatomia Histologia Embryologia, vol.00, pp.1-8, 2022 (SCI-Expanded)
The pineal gland and melatonin secreted from the gland regulate the biological clock
and adaptation to seasonal changes, glucose balance, nutrition and locomotor activities. In this study, the pineal gland of the Lake Van fish was examined anatomically
and histologically. The melatonin level secreted from the pineal gland was determined
in fish plasma sampled from both lakes and streams during reproduction migration.
The pineal gland in the Lake Van fish, as in other teleost fish, is located in the head,
under the translucent pineal window, which does not contain many pigment cells. The
gland consists of pineal vesicle and pineal stalk parts on the dorsal sac in the Lake Van
fish. It was determined that the pineal gland showed good vascularity. The presence
of pinealocytes and different types of cells in the pineal organ was determined histologically. Pinealocytes were intensely localized in the lumen of the pineal vesicle. The
plasma melatonin level increased in fish passing from lake to stream for reproductive
migration.