254 



F. MILLER AND A. BOHLE 



Hektorit oder um das ebenfalls zur Montmorillonit- 

 reihe gehorende Nontronit handeln. 



Die bei der Steinmiillerlunge gemessenen Netz- 

 ebenenabstande entsprechen dem Bild des Montmo- 

 rillonits. 



Das Beugungsbild, das bei der Kohlenhauerlunge 

 erhalten wurde, Iief3 sich nur schwer einordnen. In 

 der Mehrzahl stimmen die Netzebenenabstande und 

 die Intensitiit der einzelnen Beugungsringe mit denen 

 des Quarzes Uberein. 



Bei einem Vergleich der fianf in dieser Arbeit auf- 

 gezeigten Haufigkeitsverteiiungskurven ergibt sich, 

 daB die Maxima fUr die Lange der Teilchen zwischen 

 0,15 // und 0,35 /< bzw. fiir die Breite zwischen 0,045 

 und 0,15 // liegen. Das bedeutet, daB ein erheblicher 

 GroBenunterschied zwischen friiheren lichtoptischen 

 und den vorliegenden elektronenmikroskopischen 

 StaubkorngroBenbestimmungen besteht. Die Frage, 

 wie es zu diesen unterschiedlichen Ergebnissen 



kommt, laBt sich leicht an Hand eines hoher ver- 

 groBerten Staublungenschnittbildes klaren. Es zeigt 

 sich hier namlich, daB Partikel, die bei geringerer 

 VergroBerung als wenige groBe Teilchen erscheinen 

 miissen, in Wirklichkeit viele zusammengelagerte 

 feinste Teilchen sind. 



Die Konsequenzen, die sich aus diesen Ergebnissen 

 fiir die Staubbekampfung und damit fiir die Verhii- 

 tung der Silikose ergeben, sind leicht einzusehen. 

 Bei den praktischen Staubmessungen und den bishe- 

 rigen AbwehrmaBnahmen gegen die schiidigenden 

 Lungenstaube wurden namlich vorwiegend Partikel 

 hoherer GroBenordnungen beriicksichtigt. Nach die- 

 sen und anderen elektronenoptischen Untersuchun- 

 gen diirfte aber nur eine solche Prophylaxe Aus- 

 sicht auf Erfolg haben, die es versteht, auch — und 

 man darf wohl sagen: vor allem — die Feinststaube 

 unter 0,5 n aus der Lunge fernzuhalten. 



Electron Microscopy of the Glomerular Basement 

 Membrane in Experimental Amyloidosis of the Mouse 



F. Miller and A. Bohle 



Department of Pathology and Laboratory of Electron Microscopy, University of Innsbruck, Austria, 

 and Department of Pathology, University of Heidelberg. Germany 



Recent investigations of the renal glomerulus (13, 

 14, 18, 21) with improved technique have placed on 

 a firmer basis our concepts of this complicated 

 structure. The continuous basement membrane of 

 the capillary tuft is covered on the inside by the 

 attenuated and porous sheet of the endothelium and 

 on the outside by the interdigitating foot processes 

 of the visceral epithelial cells. The basement mem- 

 brane is built up of three layers. A dense osmio- 

 philic middle layer (lamina densa, Yamada (21)) is 

 lined on either side by a less osmiophilic inner and 

 outer layer (lamina rara interna and externa, Yamada 

 (21); inner and outer cement layer. Pease (13)). The 

 middle layer in the mouse glomerulus is about 600 A 

 thick (18, 21). The inner and outer layers are about 

 300 A thick (18). Hall (4) apparently called the 

 entire basement membrane lamina densa and did 

 not further comment upon the less osmiophilic 

 layers. Policard et al. (16) conceived of the outer 

 layer as an intermediate space. Hall (3) described 

 pores in the basement membrane after fixation in 

 buffered formalin and formalin-alcolhol mixtures 

 but could not find them after osmium fixation. 

 Rhodin (18) found a lamellated, spongy structure 

 of the osmiophilic middle layer, and Yamada (21) 

 observed a dense feltwork of fine filaments about 

 30 A thick in the lamina densa. Piel ct al. (15) 

 noted a thickening of the basement membrane in 

 the early stage of the Masugi nephritis of the rat. 



The present work gives a preliminary report on 

 the basement membrane of the mouse glomerulus 

 in experimental amyloidosis. 



Amyloidosis was produced by the method of Letterer 

 (7) as modified by Latvalahti (6). White mice were given 

 20 injections of 0.5cc Natrium-Casein (Merck) suspended 

 in n/10 NaOH (pH 10.0) subcutaneously together with 

 0.5 lU ACTH (Hoechst) over a period of 4 weeks. The 

 kidneys were exposed under light ether anaesthesia and 

 pieces of the cortex of about I mm^ were fixed for 4 hours 

 in I "o osmium tetroxide buflfered at pH 7.2 in the manner 

 of Palade (10). The tissue was embedded in butyl- 

 methylmethacrylate (95:5) and polymerized at 47^ using 

 ] ",, dichlorobenzoyl peroxide as a catalyst. A large area 

 of the tissue was sectioned very superficially on the Sitte 

 (19) ultramicrotome and controlled in a phase contrast 

 microscope. When a glomerulus was cut the tissue block 

 was trimmed to an area of about 0.5 : 0.5 mm under a 

 reflected light microscope in such a way that the glomer- 

 ulus was located in the center of the cut surface. Thin 

 sectioning was then done with glass knives. The sections 

 were mounted on Athene specimen grids by a method 

 developed by H. Sitte (20) under a phase contrast micro- 

 scope. Using this method it was possible to move the 

 glomerulus into one of the central meshes of the specimen 

 grid. This was necessary because of the small mobility 

 of the stage of the microscope used. Furthermore, the 

 entire glomerulus could be observed without being par- 

 tially covered by the bars of the grid. Sections were studied 

 with a Siemens microscope (UM 29) without sublimation 

 of the methacrylate at a low beam intensity. The objective 

 aperture was approx. 50 //. Paraffin-embedded sections 

 were stained for light microscopy with various methods 

 suitable for the detection of amyloid. 



