THE STRUCTURE OF THE ELEMENTARY TISSUES. 



35 



seen arranged in various directions, sometimes appearing to pass in a 

 more or less circular or spiral manner round a small gelatinous mass of 

 changed white fibres. The cells of the tissue are not arranged in a very 

 regular manner, as they are contained in the spaces (areolae) between the 

 fibres. They communicate, however, with one another by branched 

 processes, and also with the cells forming the walls of the capillary 

 blood-vessels in their neighborhood. The fibres are connected together 

 with a certain amount of albuminous cement substance. 



B. Special Forms. (a.) Gelatinous Tissue. 



Distribution. Gelatinous connective tissue forms the chief part of 

 the bodies of jelly fish ; it is found in many parts of the human embryo, 



FIG. 37. 



FIG. 38. 



FIG. 37. Tissue of the jelly of Wharton from umbilical cord, a, connective-tissue corpuscles ; 

 6, fasciculi of connective tissue; c, spherical formative cells. (Frey.) 



FIG. 38. Part of a section of a lymphatic gland, from which the corpuscles have been for the 

 most part removed, showing the adenoid reticulum. (Klein and Noble Smith ) 



but remains in the adult only in the vitreous humor of the eye. It may 

 be best seen in the last-named situation, in the " Whartonian jelly" of 

 the umbilical cord, and in the enamel organ of developing teeth. 



Structure. It consists of cells, which in the vitreous humor are 

 rounded, and in the jelly of the enamel organ are stellate, imbedded 

 in a soft jelly-like intercellular substance which forms the bulk 

 of the tissue, and which contains a considerable quantity of mucin. In 

 the umbilical cord, that part of the jelly immediately surrounding the 

 stellate cells shows marks of obscure fibrillation (Fig. 37). 



(b.) Adenoid or Retiform. 



Distribution. It composes the stroma of the spleen and lymphatic 

 glands, and is found also in the thymus, in the tonsils, in the follicular 



