Seasonal Changes in Thyroid Gland Morphology of Male Gray Squirrels

1960 ◽  
Vol 24 (4) ◽  
pp. 421 ◽  
Author(s):  
Roger A. Hoffman ◽  
Charles M. Kirkpatrick
Keyword(s):  
Thyroid Gland ◽  
Seasonal Changes

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

2020 ◽  
Author(s):  
Amit Singh Vishen ◽  
Varsha Gupta ◽  
S.P. Singh ◽  
Abhinov Verma ◽  
Rakesh Kumar Gupta ◽  
...  
Keyword(s):  
Thyroid Gland ◽  
Seasonal Changes ◽  
Squamous Epithelium ◽  
Poultry Farm ◽  
Follicular Cells ◽  
Climatic Variations ◽  
Reticular Fibers ◽  
Poultry Birds ◽  
The Tropics ◽  
Apparently Healthy

Background: 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 thyroid gland.Methods: 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.Result: 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.

scholarly journals SEASONAL CHANGES IN THE THYROID GLAND IN THE MALE COBRA,NAJA NAJAL

1969 ◽  
Vol 136 (3) ◽  
pp. 347-354 ◽  
Author(s):  
K. W. CHIU ◽  
J. G. PHILLIPS ◽  
P. F. A. MADERSON
Keyword(s):  
Thyroid Gland ◽  
Seasonal Changes

Seasonal changes in morphology of the thyroid gland of a hibernator, Spermophilus richardsoni

1981 ◽  
Vol 59 (6) ◽  
pp. 1022-1031 ◽  
Author(s):  
Brent W. Winston ◽  
Nancy E. Henderson
Keyword(s):  
Thyroid Gland ◽  
Seasonal Changes ◽  
Thyroid Tissue ◽  
Ground Squirrels ◽  
Physiological Data ◽  
Thyroid Cell ◽  
Apparent Contradiction ◽  
Dense Granules ◽  
Apical Vesicles ◽  
Circulating Levels

Seasonal changes in morphology of the thyroid gland were studied in Richardson's ground squirrels, Spermophilus richardsoni. Animals were sampled at six times during the annual cycle, and thyroid tissue was examined at the light and electron microscope levels. Synthesis and resorption of thyroglobulin were assessed on the bases of numbers of apical vesicles, colloid droplets, dense granules, and dense bodies, development of the Golgi apparatus and RER, and number and appearance of microvilli and mitochondria.Synthetic and resorptive activities of the throid-hormone-producing cells are high during the early prehibernation or preparative phase and decrease to moderate levels before entry into hibernation. Onset of hibernation is accompanied by further reductions in thyroid cell activities which reach minimal levels by midhibernation. Synthetic and resorptive functions increase slightly toward the end of hibernation. The reproductive phase following emergence is marked by a return to high levels of activities. Colloid storage in the follicles increases between early prehibernation and midhibernation and then decreases. The morphological observations suggest that triiodo-L-thyronine (T3) and L-thyroxine (T4) production and secretion are markedly reduced in hibernating ground squirrels. However, measurements of the circulating levels of the hormones have shown that the titres of both T3 and T4 are elevated in hibernating animals. The apparent contradiction between morphological and physiological data is discussed.

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