. Elements of histology. Histology. chap, xliii.] The Ductless Glands. 339. 497. II. The thyroid gland (Fig. 167).—The framework of this gland is in many respects similar to that of other glands, there being an outer fibrous capsule, thicker and thinner septa, and finally the fine trabecule forming the septa between the gland alveoli. These are closed vesicles of a spherical or oval shape, and of various sizes. Each vesicle is lined with a single layer of polyhedral or columnar epithelial cells, each with a spherical or oval nucleus. There is a cavity, which differs in size according to the si
. Elements of histology. Histology. chap, xliii.] The Ductless Glands. 339. 497. II. The thyroid gland (Fig. 167).—The framework of this gland is in many respects similar to that of other glands, there being an outer fibrous capsule, thicker and thinner septa, and finally the fine trabecule forming the septa between the gland alveoli. These are closed vesicles of a spherical or oval shape, and of various sizes. Each vesicle is lined with a single layer of polyhedral or columnar epithelial cells, each with a spherical or oval nucleus. There is a cavity, which differs in size according to the size of the vesicle. It contains, and is more or less filled with, a homogeneous, viscid, albu- minous fluid—the so-called colloid. In this often oc- cur degenerating nucleated lymph - corpuscles and coloured blood - corpuscles (Baber). 498. The vesicles are surrounded by networks of blood capillaries. In the connective tissue framework lie networks of lym- phatics ; between the framework and the surface of the vesicles are lymph sinuses lined with endothelium (Baber). The large and small lymphatics are often filled with the same colloid material as the vesicles, and it is probable that this colloid material is produced in the vesicles, and carried away by the lymphatics, to be finally discharged into the circulating blood. 499. Its formation in the vesicles is probably due to an active secretion by the epithelial cells of the vesicles, and to a mixture with it, or maceration by it; of the effused blood mentioned above. In some Fig. 167. — From a Section through the Thyroid Gland of Dog. p, The epithelium lining the vesi- cles ; b, the " colloid" contents of the vesicles; c, a lymphatic filled with the same material as the vesicles; d, the flhrous tissue be- tween the gland 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
Size: 1542px × 1620px
Photo credit: © Paul Fearn / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorkleineed, bookcentury1800, bookdecade1880, bookyear1883
