Anatomical and Histological Study of Thyroid and Parathyroid Glands in the Persian Squirrel (Sciurus anomalus)

Document Type : Original Articles

Authors

1 Department of Basic Sciences, Faculty of Veterinary Medicine, University of Tabriz, Tabriz, Iran.

2 Department of Basic Sciences, Faculty of Veterinary Medicine, Bu-Ali Sina University, Hamadan, Iran.

10.32598/ijvm.20.1.1005509

Abstract

Background: The thyroid gland is one of the largest endocrine glands among vertebrate species
Objectives: This study aims to examine the thyroid and parathyroid glands of the Persian squirrel duo to limited anatomical knowledge. 
Methods: Five adult male Persian squirrels were included in this study. After euthanasia, the thyroid and parathyroid glands were dissected and macroscopically evaluated. Subsequently, tissue samples from these glands were fixed, processed, and subjected to hematoxylin and eosin (H&E) and specific staining methods for microscopic analysis. 
Results: The thyroid gland of the Persian squirrel was composed of two unequal pale brown lobes without an isthmus. The caudal part of the gland was pointed, while the cranial edge was convex. The left parathyroid gland was located at the cranial edge of the thyroid gland, and the right parathyroid gland was located within the parenchyma of the thyroid gland. The cranial thyroid artery facilitates the blood supply to the glands. The colloidal substances were periodic acid schiff (PAS) positive. They appeared pale to deep orange in Masson’s trichrome staining, indicating the presence of glycoprotein with a high protein content in the more intensely colored colloids. Parafollicular cells were mainly clustered between follicles. The parathyroid gland consists of small secretory cells in a rope-like arrangement. These cells exhibited acidophilic cytoplasm, euchromatin round to oval nuclei, and a weak reaction to PAS staining.
Conclusion: Information regarding the thyroid and parathyroid glands can be highly beneficial for veterinary practitioners dealing with diseases related to the endocrine system.

Keywords

Iranian Journal of Veterinary Medicine
Volume 20, Issue 1
January 2026
Pages 143-152

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