216 



MANUAL OF HISTOLOGY. 



Ill many structures formed of connective-tissue it is probable that 



the protoplasm becomes more 

 and more expended in the 

 production of the inter- 

 mediate substance, until the 

 latter, either fibrillated or 

 streaky, appears as though 

 i only nuclei alone instead of 

 cells were left in existence. 



The total disappearance 

 also in many parts of the 

 connective-tissue cells pre- 

 sent in the embryo, may be 

 bound up with the develop- 

 ment there of numerous 

 elastic elements. This has 

 been remarked in the liga- 

 mentum nuchae of mammals 

 (Koelliker). 



131. 



We now turn to the mode 

 of occurrence of connective- 

 tissue. 



The numerous portions of 

 our body consisting of this 

 tissue offer for our considera- 

 tion fibrous and generally 

 fibrillated intermediate sub- 

 stance, cellular elements, the 

 connective-tissue corpuscles, 

 and wandering lymphoid 

 cells, and also the various 

 species of elastic fibres and networks. In some structures a few only of the 

 latter constituents occur amid a large quantity of fibrillated intermediate 

 substance ; but they are met with more abundantly in other parts, and 

 may eventually appear here and there in such excess that the glutin- 

 yielding fibres and cells begin to be obscured or actually cease to be 

 present. Thus, in some cases, we find elastic membranes and fibrous 

 networks alone, the latter being held together by a membranous inter- 

 stitial matter neither fibrous nor glutinous. They may also make their 

 appearance naked and without such a cementing medium. In that 

 numerous intermediate forms exist, however, between them, the latter 

 cannot be classed as a tissue distinct from the true connective-tissue. 



Associated with these essential form-elements of connective-tissue we 

 sometimes find other incidental constituents, such as cartilage -cells 

 ( 109), fat-cells ( 122), smooth muscle fibres (in which the Tunica 

 darios of the scrotum is very rich), blood and lymph vessels, nerve 

 fibres, &c. Here, then, we have, in consequence of these additions which 

 differ exceedingly from one another, a new ground for variableness in parts 

 formed of connective-tissue. 



These latter appear either as yielding substances, filling out the 

 spaces between organs or portions of organs, as loose enveloping masses, 



fig, 210. Different forms and stapes of development of 

 the so-called connective-tissue corpuscles, after treat- 

 ment with acetic acid. 



