VASCULAR GLANDS THYROID BODY. 227 



a faintly granular or of a somewhat oily aspect, which may be seen to exude 

 from the epithelial cells (c, c) lining their interior. 1 The vascular supply of 

 the Thyroid body is extremely abundant ; and, as in the preceding instances, 

 the subdivisions of its arteries form a very minute capillary plexus upon the 

 membrane of the vesicles. The lymphatic spaces are lined by a layer of 

 epithelium, which is often the only septum between the interior of the 

 vesicles and the lymphatic spaces. The nerves are scanty, accompanying 

 the vessels, and are derived from the cervical parts of the sympathetic. 

 The development of the Thyroid body has been shown by Mr. Gray (loc. 

 cit.), Mr. Cal lender, 2 and W. Miiller, 3 to be closely accordant with that of 

 the " ductless glands " already described. This body originates on the third 

 day in the Chick as an involution from the hypoblast of the throat opposite 

 the point of origin of the second arterial arch. On the fourth day it forms 

 a solid mass of cells, and on the fifth becoming independent of the epi- 

 thelium of the throat, it presents a bilobed form, the two lateral masses 

 being joined by a central portion or isthmus, with an outlying piece or pyra- 

 mid of very variable form. The lateral lobes are situated on each side of 

 the root of the neck, close to the separation of the carotid and subclavian 

 vessels, and between the trachea and the branchial clefts, but quite inde- 

 pendent, as far as regards their development, of either of those parts; their 

 minute structure at an early period closely corresponds with that of the 

 spleen and suprarenal glands. This body, like the Suprarenal and Thymus, 

 is of larger relative magnitude during intrauterine existence and infancy, 

 than in after life. According to Ecker 4 and Pererneschko 5 the Pituitary body 

 has the same essential structure as the vascular glands in general ; present- 

 ing vesicles containing a finely-granular blastema with nuclear particles 

 imbedded in a fibrous stroma. A minute gland-like body, first described by 

 Luschka, 6 and termed by him the Coccygeal gland, is situated near the ante- 

 rior part of the apex of the coccyx. It consists of a basis of connective tissue, 

 in which are imbedded irregularly branched tubes, that here and there 

 dilate into vesicles. The nerves proceed from the coccygeal ganglion. By 

 Luschka and others the pituitary and coccygeal bodies have been regarded 

 as the remains of the opposite extremities either of the chorda dorsalis or of 

 the primary intestinal tube. 



The recent researches of Neumann 7 and others seem to demonstrate that 

 the so-called " red marrow," occupying the cancellous tissue of the bones, 

 constitutes a kind of adenoid tissue in which lymph-corpuscles are developed. 

 The vessels of this tissue are very numerous and large, and are connected 

 by a delicate web of stellate cells, with long processes, the interstices of 

 which are filled by a homogeneous muciu-like material. Imbedded in this 

 are large numbers of cells, presenting .every grade of development between 

 lymph and fully developed white and red blood-corpuscles. These must 

 either gain entrance into the blood vascular system by penetrating the walls 

 of the capillaries, or as Hoyer thinks, the whole tissue resembles the lacuuar 

 system of the lymphatic glands, and the corpuscles are generated by fission 

 of previously existing cells u'ithin the dilated and anastomosing capillaries. 



1 See Verson, Syd. Soc. Trans, of Strieker's Manual, vol i, p. 370; and Archives 

 de Med., 1874, June. 



2 Proceed, of the Royal R>c-, vol. xvi, 1867, p. 25. 



3 Jenaischp, Zoitschrift, 1871. 



4 Art. Blutgefassdriisen in Wagner's Hanrlworterbuch, Bd. iv. 



5 Loc. cit. 6 Virchow's Archiv, Bd. xviii, p 106. 



7 Archiv der Heilknnde, 18f>9, pp. 68 and 4 J'20. See also Bizzozero, Centralblatt 

 fur die Med. Wissenschatt. 18G8, p. 885, and 18fi9, p. 149 ; Hoyer, Centralblatt, 18G9, 

 pp. 244 and 257; Palladino, Centralblatt, 1869, p. 513; and Mosler, Centralblatt, 

 1871, p. 290. 



