Observations on F I B R I L L O G E N E S I S I N T H E C O N N E C T I V E Methods and Materials

Silver impregnation of collagenous microfibrils has been applied in electron microscopy in recent years by yon Herrath and Det tmer (3), Dettmer, Neckel, and Ruska (1), Det tmer (2), Schwarz (5), Tomlin (6), and Irving and Tomlin (4). The main purpose of these authors was to determine whether the silverimpregnation picture of the so called reticulin fibers differed from that of the collagenous fibers, and how it might change with the increasing width of the microfibrils. For this purpose the impregnation of microfibrils which were isolated from the tissues was a satisfactory technique, and it provided impor tant information about the mechanism of silver impregnation. However, it seemed to be desirable to obtain in electron microscopy the same advantages of silver staining as in the light microscope, that is, to combine the impregnation with u l t ra th in sectioning.