Regeitcrafio/i of Coiinccfk'c 7'issiic. 239 



ample, a bit of sponge or fragment of elder ])ith be introduced into 

 a tissue or serous cavity it becomes completely penetrated by these 

 fibroblasts. 



Along with the connective tissue cells proper, the endothelial 

 cells of the blood and lymphatic vessels take part in the new forma- 

 tion of connective tissue. In both forms of cells mitosis prevails 

 profusely ; the young endothelial elements resulting from the cell di- 

 vision are like the other fibroblasts, being distinguishable from those 

 derived from the spindle cells only at their places of origin from the 

 blood vessels, where they are forming capillary tubes. Whether 

 endothelial cells ever form fibrils or solely develop into vessels is 

 not fully determined (for details consult ]\Iarchand). Another 

 long debated question, whether the leucocytes actually take part in 

 the connective tissue formation and are transformed into connec- 

 tive tissue cells, may be answered on the basis of more recent 

 studies (Marchand) that the white corpuscles which exude from 

 the blood vessels are principally concerned in the removal of for- 

 eign matter and products of disintegration, that they furnish nutri- 

 tive substance in case of their own destruction, but are incapable 

 of forming intercellular material and therefore cannot be consid- 

 ered as actual constructive elements of the connective tissue. The 

 presence of these leucocytes in every area of proliferating connec- 

 tive tissue is therefore dependent upon their entrance partly from 

 the vessels, partly from points of lymphoid development to be 

 found commonly along the bloodvessels in any tissue. The whole 

 cellular group more or less closely approaching leucocytes and cells 

 from the lymph glands (lymphocytes), but because of their more 

 conspicuous cytoplasm or a variety of granulations of their proto- 

 plasm given other names (plasma cells, iiiasf cells, leucocytoid cells, 

 polyhlasts, klasinafocytes) , are also found in the growing connective 

 tissue. The origin of these cells and tlie question of their relationship 

 is still rather uncertain ; probably they are all immigrants originating 

 from lymphocyte depots. Giant cells (polykaryocytes) are also often 

 observed in developing connective tissue, and multinucleated cells, 

 especially when foreign bodies are present ; they are formed partly 

 from the multiplying spindle cells, partly from endothelial cells, and 

 may be regarded as cells whose protoplasm has increased and whose 

 nuclei have multiplied more rapidly than cell division could keep pace 

 (proliferation giant cells). According to another view they are 

 caused by coalescence of closely grouped embryonic cells (congluti- 

 nation giant cells). 



Opinions concerning the mode of origin of elastic fibres in the re- 



