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Anatomical and histological characteristics of the pituitary gland in the bottlenose dolphin (Tursiops truncatus) from the Adriatic Sea

The structure of the pituitary gland was studied in 3 bottlenose dolphins (Tursiops truncatus) from the Adriatic Sea. This species is legally protected in Croatia. All examined animals died of natural causes and were found stranded along the eastern Adriatic coast. The pituitary gland is a rectangular body suspended at the base of the brain and situated in a depression of the sphenoid bone, clearly identififi ed as sella turcica. The gland was divided into the adenohypophysis and the eurohipophisis, interconnected by thick layer of connective tissue. Pars distalis and pars tuberalis were observed in the adenohypophysis while the pars intermedia was lacking. The pars distalis was built of three main cell types: acidophils, basophils and chromophobes. Most of the acidophils were situated in the centre of the gland while chromophobes occurred dorsal and basophils ventral. Pars tuberalis was composed of cords of polygonal and vacuolated cells, which were in close association with numerous blood vessels. Large numbers of colloid-containing follicles were observed throughout the pars tuberalis. The neurohypophysis of the bottlenose dolphin consisted of unmyelinated nerve fifi bres among which numerous pituicytes were scattered.

pituitary gland; adenohypophysis; neurohypophysis; bottlenose dolphin; Tursiops truncatus; Adriatic Sea

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