Morphometry, topography and arterial supply of the thyroid gland in rhesus monkeys (Macaca mulatta Zimmermann, 1780)

Abstract

Abstract The purpose of this research was to investigate the measures, topography, and vascularization of the thyroid gland in Macaca mulatta, a non-human primate. The study involved the dissection of ten male adult cadavers of Macaca mulatta. The length, width, and thickness of the right lobe of the thyroid were 2.552 ± 0.341, 1.019 ± 0.137, and 0.729 ± 0.137 cm. These measures in the left thyroid lobe were 2.406 ± 0.299, 1.013. ± 0.087, and 0.769 ± 0.083 cm. The study found no significant differences in the measures of the left and right lobes of the thyroid gland in rhesus monkeys. Regarding topography, the thyroid gland was located ventrolateral to the trachea, similar to its position in other mammal species. The cranial pole of the gland was closely related to the cricoid or thyroid cartilage, while the caudal pole showed variable positioning to the tracheal rings. The isthmus, a thin band of tissue connecting the lobes, was present in all specimens. The cranial thyroid artery was found to originate from the external carotid artery in most specimens. It supplied the thyroid gland and sent branches to muscles in the neck region. The caudal thyroid artery, originating from the common carotid artery, provides additional blood supply to the gland and sends a branch to the esophagus. This research contributes to knowledge about the thyroid gland in non-human primates, specifically Macaca mulatta. The findings provide critical information for comparative studies and understanding the thyroid gland's role in health and disease.