172 



PRACTICAL HISTOLOGY. 



[XII. 



FIG. 142. Mucous Tissue of Umbilical Cord 

 of Fretus. MUller's lluid and logwood, x 

 300. 



anastomose with each other. Between the cells is a fluid which 

 contains mucin, and according to the stage of development of the cord, 

 there, is a grejitoror less number of fibres. The older the cord, the 



more the fibres increase in num- 

 ber, and its characters approach 

 those of ordinary connective- 

 tissue. A better view of the 



finer processes is obtained by 

 examining the. tissue in normal 

 saline (fig. 142). 



ADENOID TISSUE. 



Adenoid, Ketiform, or Re- 

 ticular Tissue consists of a re- 

 ticulum or network of fine fibrils, 

 which run in all directions, 

 forming a meshwork in several 

 planes. Some regard it as made 

 up of branched corpuscles, the processes of which anastomose. 

 In the meshes are leucocytes or lymph-cells, which usually occur 

 in such numbers as to obscure the presence of the fine meshwork 

 in which they lie. 



It is very widely distributed, e.g., in lymphatic glands, simple 

 and compound, tonsils, solitary glands, and Peyer's glands ; in the 

 bronchial, pharyngeal, nasal, intestinal mucous membrane, spleen, 

 thymus, and a few other situations. 



11. Adenoid Tissue of Lymphatic Glands. This may be pre- 

 pared in several ways. 



(i.) Harden an abdominal lymphatic gland of a calf or kitten for 

 two weeks in MUller's fluid. Make sections, and shake up one in a 

 test-tube with some water ; this dislodges the lymph corpuscles, and 

 in places leaves the fine reticulum visible. 



(ii.) A better plan is to inject into a fresh lymph gland a J per 

 cent, solution of osmic acid, or J per cent, solution of silver nitrate. 

 In either case an oedema is produced which separates the parts and 

 reveals the network. The injection is made by means of a hypo- 

 dermic syringe (fig. 1 26). The syringe is filled with the solution, and 

 the sharp nozzle is thrust into the gland, and the contents of the 

 syringe rapidly injected haphazard into the organ. It passes in, and 

 forms, as it were, an oedema, and separates, and at the same time 

 hardens, the constituent parts of the organ. This is the method of 

 interstitial injection, one which is frequently employed. 



(iii.) The gland may be hardened for twenty-four hours in picric 



