Chapter XVII 



GOLGI APPARATUS, CANALICULI OF HOLMGREN 

 AND OTHER CYTOPLASMIC FORMATIONS 



Golgi apparatus and the canaliculi of Holmgren in animal cells :- 

 By using methods of silver nitrate impregnation, GOLGI (1898) 

 brought out in the cytoplasm of nerve cells (Purkinje cells and 

 invertebrate ganglia of Strix flammea) a network of very fine 

 filaments to which has been given the name internal reticular ap- 

 paratus of Golgi. This formation was made the object of impor- 

 tant studies by Cajal. Kopsch showed later that the G<)lgi 

 apparatus can also be brought out by osmic impregnation at 40° C. 



This later method has the advantage over the preceding 

 that it is much easier to use, for, unlike impregnation with silver, 

 it does not result in so many failures. For this reason, it has been 

 the starting point for a great deal of research which has revealed 

 in most animal cells, formations which osmic acid blackens, just 

 as it does the Golgi apparatus described by GoLGi and Cajal. These 

 formations, in spite of their widely differing morphological aspects, 

 have been grouped with the Golgi apparatus on the single basis 

 that they stain like it. These formations are not generally repre- 

 sented by a network but by small elements scattered in the cyto- 

 plasm, appearing as spherical or ovoid bodies, composed of a 

 chromophobic substance surrounded by a chromophilic substance 

 which is thicker on one side than on the other. They are known 

 as dictyosomes or Golgi bodies. 



Many cytologists today think that the Golgi apparatus is a 

 permanent feature of cytoplasm in the same way as is the chondri- 

 ome, and there has been described, during mitosis, a division of 

 the Golgi bodies between the daughter cells which has been called 

 dictyokinesis (Perroncito). Finally, scientists are coming to the 

 belief that this apparatus is the center of elaboration of metabolic 

 products. In brief, it is thought to play the role formerly attrib- 

 uted, first, to the ergastoplasm and, later, to the chondriome. So 

 the Golgi apparatus may be said to have supplanted the chondriome 

 for those who adhere to this view. 



The Golgi apparatus, however, is not, like the chondriome, a 

 well defined system. It is not visible in living material nor can 

 it be revealed by microdissection (Kite and Chambers). It can 

 be demonstrated only by methods which, as we shall see, are in 

 no wise specific. Morphologically, it is so imperfectly character- 

 ized that Bowen said "The Golgi apparatus is above all a sub- 

 stance, a cellular apparatus, whose modelling has only a secondary 

 interest." Such a definition could only be acceptable if the Golgi 

 apparatus were composed of a well-defined substance. Now its 

 chemical nature is completely unknown and it does not even have 

 definite characteristics of fixation and staining. It is not certain, 



