4.5.
HANDLING THICK EMBEDDING MEDIA
89
of carrying over a minimal quantity of the final bath into the embedding
capsule.
The gelatin capsules ordinarily used for final embedment may contain
deleterious quantities of water. In many laboratories these are gently
baked before use, or kept in desiccators. The necessity for this will depend
upon local atmospheric conditions, but if there is doubt, precautions had
better be instituted. Recently, disposable plastic "capsules" have been
marketed specifically for embedding purposes by Better Equipment for
Electron Microscopy, Inc., P. O. Box 132, Jerome Ave. Sta., Bronx 68,
New York.
It is the size "00" capsule that fits the standard chuck of the PorterBlum microtome, and hence this is the size most commonly used in this
country.
Loaded gelatin capsules are most simply labeled by writing on the
surface with ink. A better label, written on paper, can be included within
the capsule and so become embedded in the plastic. Labels of this sort
must be of such a small size that they can be fitted to the curvature of
the side walls of the capsule, and they should be placed within the
capsule before its other contents.
If a specimen does not require particular orientation, it is most convenient to mount the entire hardened contents of a capsule directly in
the microtome chuck, and only trim the head region to expose the
tissue. Thus, the plug of plastic serves as the support arm carrying the
specimen.
4.5. Handling Thick Embedding Media
There are several special problems associated with the handling of
thick resin mixtures, particularly those of the epoxy and polyester
families. Some of the components and blends constitute the stickiest
and messiest substances that one is ever apt to handle. Furthermore,
some of them are mildly poisonous, and several have a bad reputation
as potential producers of an allergic dermatitis which can be extreme.
Yet, preparative problems make it almost impossible to keep these substances off tools, bench tops, and hands. The considerable viscosity of
such compounds makes mixing, pouring, and cleaning operations unusually difficult.
HANDLING THICK EMBEDDING MEDIA
89
of carrying over a minimal quantity of the final bath into the embedding
capsule.
The gelatin capsules ordinarily used for final embedment may contain
deleterious quantities of water. In many laboratories these are gently
baked before use, or kept in desiccators. The necessity for this will depend
upon local atmospheric conditions, but if there is doubt, precautions had
better be instituted. Recently, disposable plastic "capsules" have been
marketed specifically for embedding purposes by Better Equipment for
Electron Microscopy, Inc., P. O. Box 132, Jerome Ave. Sta., Bronx 68,
New York.
It is the size "00" capsule that fits the standard chuck of the PorterBlum microtome, and hence this is the size most commonly used in this
country.
Loaded gelatin capsules are most simply labeled by writing on the
surface with ink. A better label, written on paper, can be included within
the capsule and so become embedded in the plastic. Labels of this sort
must be of such a small size that they can be fitted to the curvature of
the side walls of the capsule, and they should be placed within the
capsule before its other contents.
If a specimen does not require particular orientation, it is most convenient to mount the entire hardened contents of a capsule directly in
the microtome chuck, and only trim the head region to expose the
tissue. Thus, the plug of plastic serves as the support arm carrying the
specimen.
4.5. Handling Thick Embedding Media
There are several special problems associated with the handling of
thick resin mixtures, particularly those of the epoxy and polyester
families. Some of the components and blends constitute the stickiest
and messiest substances that one is ever apt to handle. Furthermore,
some of them are mildly poisonous, and several have a bad reputation
as potential producers of an allergic dermatitis which can be extreme.
Yet, preparative problems make it almost impossible to keep these substances off tools, bench tops, and hands. The considerable viscosity of
such compounds makes mixing, pouring, and cleaning operations unusually difficult.