48 THE CONNECTIVE TISSUES 



They have an irregular, stellate form with branching cytoplasmic 

 processes, and have the appearance of a syncytium. The nucleus 

 is relatively large and mitotic figures are often evident. An appar- 

 ently homogeneous, liquid, intercellular substance fills in the spaces 

 between adjoining cells. (Fig. 2().) From such mesenchyme, or 

 embryonic connective-tissue cells, are derived the various dift'er- 

 entiated cells that form the cellular elements of the connective-tissue 

 types of the adult. They also give rise to cells that in turn differ- 

 entiate into endothelium, blood, and smooth muscle cells. 



Fig. 26. — Diagram of mesenchyme cells. 



MUCOUS TISSUE. 



This is a special type of connective tissue found in embryos, and 

 reacts to stains for mucus. In the fresh condition, as seen in the 

 case of an umbilical cord, it presents a jelly-like appearance due to 

 the abundant gelatinous intercellular material. Within this gelatin- 

 ous matrix are fine fibers and scattered cells with long branching 

 processes. The ends of the branches of one cell are in contact with 

 other cell branches, so that a network of cells and fibers extends 

 throughout the mucoid ground substance. In the case of the 

 umbilical cord this tissue occurs between the blood vessels and ducts 



