. The biology of the frog. Frogs. INTERNAL SECRETION AND ENDOCRINE GLANDS 229. Fig. 73.—D iagram showing the position of the thyroid glands, /; I, lateral process of hyoid cartilage; , thyro-hyoid process of hyoid. described some thyroid tissue (accessory thyroid) on the ventral side of the hyoglossus muscle, and I have been able to confirm this observation in Rana pipiens. The tissue of the thyroid shows a unique structure, being com- posed of a mass of rounded follicles united by a small amount of con- nective tissue in which there is a rich supply of blood vessels. Each fol- licle is a p
. The biology of the frog. Frogs. INTERNAL SECRETION AND ENDOCRINE GLANDS 229. Fig. 73.—D iagram showing the position of the thyroid glands, /; I, lateral process of hyoid cartilage; , thyro-hyoid process of hyoid. described some thyroid tissue (accessory thyroid) on the ventral side of the hyoglossus muscle, and I have been able to confirm this observation in Rana pipiens. The tissue of the thyroid shows a unique structure, being com- posed of a mass of rounded follicles united by a small amount of con- nective tissue in which there is a rich supply of blood vessels. Each fol- licle is a perfectly closed sac lined by a single layer of cubical epithelial cells. In the center of each follicle is a colloidal mass of transparent substance which probably represents the secretion of the epithelial lining. What knowledge we have of the functions of the thyroid in the frog indicates that they are much the same as in man and other mammals. The removal of the thyroid in the higher verte- brates commonly pro- duces fatal results un- less there are accessory organs, such as the parathyroids, which in some of the mammals are able to maintain life in the absence of the thyroid. Removal of a part of the gland creates, as a rule, but little disturb- ance. Life may be maintained for a considerable period after complete removal of the thyroid by giving injections. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Holmes, Samuel J. (Samuel Jackson), 1868-. New York : The Macmillan company
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Keywords: ., bookauthorholmessamueljsamuelja, bookcentury1900, bookdecade1920
