. A text-book of embryology for students of medicine [electronic resource]. Embryology; Embryology. THYROID, PARATHYROID, AND THYMUS BODIES. 231 the mature gland. The breaking down is probably responsible also for the in thymus. Not until after birth do the glands of the two sides of the body unite to form a single unpaired structure, and the development of the thymus is not completed until the end of the second year of life. Hav- ing attained its full development, the organ begins to retrograde, and at the time of puberty has almost disap- peared. Although sometimes per- sistent throughout li
. A text-book of embryology for students of medicine [electronic resource]. Embryology; Embryology. THYROID, PARATHYROID, AND THYMUS BODIES. 231 the mature gland. The breaking down is probably responsible also for the in thymus. Not until after birth do the glands of the two sides of the body unite to form a single unpaired structure, and the development of the thymus is not completed until the end of the second year of life. Hav- ing attained its full development, the organ begins to retrograde, and at the time of puberty has almost disap- peared. Although sometimes per- sistent throughout life, it is usually represented by an insignificant vest- ige. (It has recently been said that the thymus increases in size and weight up to puberty, and that it is an active organ until the fortieth year, after which time it atrophies.) While the epithelial parts of the thymus body, represented in the fully developed organ by the corpuscles of Hassall, are derived from the entodermal epi- thelium of the third inner visceral furrow, all other parts, the lymphoid tissue, connective tissue, and blood- vessels, are products of the surroundi of the epithelial cords egular cavities of the. Fig. 115.—Thymus of an embryo rabbit of sixteen days (after Kolliker), magni- fied : a, canal of the thymus; b, upper, c, lower end of the organ. ng 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 Heisler, John Clement; Waterstone, David, former owner; Duke-Elder, Stewart, 1898-1978, former owner; University College, London. Library Services. Philadelphia : W. B. Saunders Company
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