Anti-contamination Device Research Articles

Ultrastructure of Alpha-Keratin Microfibrils

Tips from the quills of Erethyon dorsaturn (porcupine) were placed in 0.5 M thioglycollic acid at pH 5.6 for 24 hours, then fixed for 72 hours in 1% OsO4. Quills were also prepared without the thioglycollic acid treatment. The material was dehydrated in a series of ethyl alcohols and embedded in Spurr Low Viscosity Embedding Medium. Sections were cut on a Reichert 0mU2 ultramicrotome and stained for 40 minutes at 37°C with saturated lead hydroxide. Electron micrographs (primary magnification 150,000 x) were taken with an A.E.I. EM6B electron microscope at 60 KV equipped with 25 μ and 50 μ objective apertures and an anticontamination device. Focal series of silver to silver gray sections were taken with a 0.1 μ change of focus (1 click of fine focus control). For the Markham rotation technique a constant speed motor (The General Industries Co., Elyria, Ohio) and a Strobatac (Model 1538-A, General Radio) was used.

A double-tilting heating stage for an electron microscope

An electron microscope specimen holder is described which allows specimens to be heated to 800°C with a very small heat input and tilting of the specimen by at least 20° in all azimuths. The heating unit is of the furnace type. Both specimen and heating coil are located in a small ball which is the central portion of a universal suspension, chosen to minimize both heat losses by conduction and friction between the ball and its bearings. The present version of the holder has been designed for the Siemens electron microscope but its working principles can be applied to other types of microscope. The holder can be inserted into the microscope through the standard air lock, and it allows full traverse movement of the object stage and the use of an anticontamination device. In order to overcome space restrictions the top ring of the objective pole piece has been replaced by a new one of larger bore.