CELL DIFFERENTIATION AND THE ELEMENTARY TISSUES 



part of the bodies of such marine animals as the jelly-fish. It is found in 

 many parts of the human embryo. It may be best seen in the " Whartonian 

 jelly" of the umbilical cord and in the enamel organs of developing teeth. 





FIG. 41. 



FIG. 42. 



FIG. 41. Mucous Connective Tissue from the Umbilical Cord, a, Cells; b, fibrils. 



FIG. 42. 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.) 



Structure. It consists of cells, which in the jelly of the enamel organ 

 are stellate, embedded in a soft jelly-like intercellular substance which forms 

 the bulk of the tissue. 



Adenoid or Lymphoid Tissue. Distribution. This variety of tissue 

 makes up the stroma of the spleen and lymphatic glands, and is found also 



FlG. 43. Portion of Submucous Tissue of Gravid Uterus of Sow. a, Branched cells, 

 more or less spindle-shaped; b, bundles of connective tissue. (Klein.) 



in the thymus, in the tonsils, and in the follicular glands of the tongue; in 

 Peyer's patches, in the solitary glands of the intestines, and in the mucous 

 membranes generally. 



Structure. Adenoid or retiform tissue consists of a very delicate network 



