586 



SPECIAL HISTOLOGY. 



divisions of the organ are then constituted; these have special, and 

 indeed thicker coats, with which, histly, a fibrous membrane investing 

 the whole organ is conjoined, 



§ 181. With respect to its intimate structure, there is not much to 

 be said about the fibrous tissue or stroma of the thyroid gland, inasmuch 

 as it consists of common interlaced bundles of connective tissue, inter- 

 mixed with fine clastic fibres and also, on the surface, contains a certain 

 quantity of fat-cells. The gland vesicles themselves, in Man, present 

 such varied conditions of structure, that it is not easy to say what is 

 their normal state. According to what I have observed in Man and 

 also in animals, I must, with regard to this point, declare that, analo- 

 gous to the true gland vesicles, for instance, of the mucous glands, they 

 consist of a membrana propria, an epithelium, and fluid contents. The 

 membrane is quite homogeneous, transparent, and delicate, 0-0008 of a 

 line thick ; and, like all membranes of the sort, is rendered more distinct 

 by caustic alkalies, in which it swells up. On its inner surface lies a 

 single layer of epithelium, composed of polygonal, finely granular, trans- 

 parent cells of 0-004:-0-006 of a line, with simple nuclei ; whilst the 

 space surrounded by these cells is occupied with a clear, somewhat vis- 

 cous fluid, with a tinge of yellow 

 in its color, the behavior of which 

 towards alcohol and nitric acid 

 and when the gland is boiled, 

 clearly manifests the presence of 

 much albumen. This is the cha- 

 racter of the contents in the healthy 

 thyroid gland of Man, particularly 

 in children ; if the organ, how- 

 ever, is but very little altered, 

 conditions, in many respects dif- 

 ferent, are presented. Very fre- 

 quently, instead of a regular 

 epithelium, nothing is met with 

 but a fluid mixed with minute, clearer or darker granules and free 

 nuclei : althoue-h I am ifrnorant whether this condition of the contents 

 does not take place till after death, or whether it is to be regarded as 

 abnormal. For we so frequently observe, in the granular fluid, a greater 

 or less number of the same cells, Avhich at other times exist as epithe- 

 lium, often pale and as if half dissolved, that it is impossible to avoid 

 the conclusion, that in these cells we have an instance of that post-mor- 

 tem decomposition, so frequently observed in the human subject. On 

 the other hand, the pathological nature of the change in the thyroid 



Fig. 240. — Some gland-vesicles from the thyroid gland of a Child, magnified 250 diam. : 

 a, connective tissue between them; h, membrane of the gland-vesicles; c, their cpithditim. 



