GRANULES AND FAT OF STRIATED MUSCLE 39 



VI. PHYSIOLOGICAL SIGNIFICANCE OF INTERSTITIAL GRANULES 



AND FAT DROPLETS 



Physiological significance of Irue interstitial granules 



Several investigators have held that true interstitial granules 

 give origin to fat droplets either by a fatty metamorphosis or by 

 serving as a focus about which fat is deposited. Kolliker ('88-89) 

 belived that fat droplets in muscle fibers arise from true inter- 

 stitial granules by a process of fatty metamorphosis and Schaeffer 

 ('93) advanced similar views. Holmgren ('10) states that the 

 deposition of fat in muscle fibers is apparently influenced by the 

 true interstitial granules but he thinks the granules are actually 

 transformed into fat only under exceptional or pathological con- 

 ditions. Altmann ('94) held that his bioblasts (true interstitial 

 granules) are not transformed in toto into fat but act as a focus 

 within and around which fat is accumulated. Arnold has advo- 

 cated similar views. Bell ('11) does not believe that granules 

 which stain with acid fuchsin (Altmann' s granules) give origin 

 to fat and he is of the opinion that true interstitial granules do 

 not occur in vertebrate muscle. His conception of the deposition 

 of fat in muscle fibers is nevertheless essentially in accord with the 

 theory advanced by Altmann. Bell holds, namely, that the fat 

 of muscle fibers is deposited as 'liposomes' around a pre-existing 

 non-fatty body, possibly an albumino-lipoid. As we have seen, 

 Altmann's granules are probably an albumino-lipoid formation 

 and conversely albumino-lipoids may be expected to stain with 

 Altmann's acid fuchsin. 



The reader is referred to the literature for a presentation of the 

 arguments offered by various authors in support of the idea 

 that true interstitial granules give origin to fat droplets or serve 

 as foci about which fat is deposited. It may be said that, at 

 present, the truth of such a conception is not sufficiently demon- 

 strated to warrant us in believing that there is a genetic relation- 

 ship between true interstitial granules and fat droplets. 



According to Holmgren ('07, '10) the colorable substance 

 (method of Benda) of the interstitial granules is necessary to the 

 proper functioning of the contractile elements. During the 



