Krupp P P, Young R A, Frink R
Anat Rec. 1977 Apr;187(4):495-514. doi: 10.1002/ar.1091870406.
The morphology of the thyroid gland of the woodchuck, Marmota monax, was studied during the four seasons of the year. In the spring the thyroid is extremely heterogenous in appearance. Some follicular cells appear quite active. They contain a well defined Golgi apparatus, abundant large colloid droplets and pseudopodia but few, if any, apical vesicles. Other less active cells have poorly defined rough surfaced endoplasmic reticulum and lack a well developed Golgi apparatus. They do not contain apical vesicles or colloid droplets. Summer thyroids have uniformly small follicles which are lined by high cuboidal cells containing numerous mitochondria, apical vesicles, abundant rough surfaced endoplasmic reticulum, and lipid droplets but few colloid droplets. There is extensive lateral and basal infolding of the cytoplasmic membranes in these cells. In the fall and winter the follicles are larger than in the summer and contain more colloid. Numerous heterogeneous dense bodies appear in the cytoplasm of the follicular cells in the fall and increase in number in the winter when there is an obvious sparsity of such glycoprotein synthetic organelles as Golgi apparatus and rough surfaced endoplasmic reticulum. These morphologic changes are compared with previous studies of thyroid structure and function in other animals and are correlated with the seasonal physiologic activities of the woodchuck.
对土拨鼠（Marmota monax）甲状腺在一年四个季节中的形态进行了研究。春季时，甲状腺外观极不均匀。一些滤泡细胞看起来相当活跃。它们含有界限分明的高尔基体、大量大的胶体小滴和伪足，但顶端小泡很少（如果有的话）。其他不太活跃的细胞糙面内质网界限不清，且缺乏发育良好的高尔基体。它们不含顶端小泡或胶体小滴。夏季的甲状腺滤泡均匀地小，由高立方体细胞排列而成，这些细胞含有大量线粒体、顶端小泡、丰富的糙面内质网和脂滴，但胶体小滴很少。这些细胞的细胞质膜有广泛的侧向和基底内褶。秋季和冬季的滤泡比夏季的大，且含有更多胶体。秋季时，滤泡细胞的细胞质中出现许多异质性致密体，到冬季数量增加，此时高尔基体和糙面内质网等糖蛋白合成细胞器明显稀少。将这些形态学变化与之前对其他动物甲状腺结构和功能的研究进行了比较，并与土拨鼠的季节性生理活动相关联。
