<div style="text-align: justify;"><strong>Background: </strong>Chabro is a strain of poultry birds especially designed for backyard farming and is more adoptive to climatic variations in the tropics. The thyroid gland plays an important role in controlling basal metabolic rate. The histoarchitectural changes of the gland in association with seasonal changes has not been studied so far in Chabro. The present study describes the season related variations in the histometry of &nbsp;thyroid gland.<br /><strong>Methods:</strong> Micrometrical studies were conducted on thyroid gland of eight to ten weeks old 24 apparently healthy Chabro chickens procured from Poultry Farm, DUVASU, Mathura after approval of CPCSEA. For this study the chickens were divided into two groups consist of 12 chickens in each group reared in summer and winter seasons.<br /><strong>Result: </strong>Histologically, the thyroid gland was composed of stroma and parenchyma. The capsule had outer thick adipose and inner thin fibrous layers. The follicles were filled with colloid produced by the follicular cells. The percentage of small follicles was more followed by medium and large follicles. The follicles were lined by simple squamous epithelium in summer and cuboidal epithelial cells in winter. All micrometrical parameters, amount of reticular fibers, percentage of large and active follicles were higher in winter. &nbsp;</div>

Histometrical Changes in the Thyroid Gland of Chabro Chicken Reared during Summer and Winter Seasons