2.9.
TISSUE CULTURES AND CELL SUSPENSIONS
31
indeed, every pathologist recognizes them to a degree at the level of
conventional microscopy. Where possible, therefore, efforts should be
made toward obtaining juvenile or young adult tissue.
The human, after all, is a large animal with consequently much more
and much denser connective tissue in most places than a mouse or a rat.
Thus, tissue which preserves easily when taken from a small animal may
present serious problems when removed from humans.
Although this section may seem discouraging to those who would do
human pathology, this field promises particularly rich rewards, and ways
to success in particular situations are being found and will be found. One
should not be unduly discouraged if one's first efforts are dismally disappointing. It is certainly advisable for the novice to have a taste of success first by studying the normal morphology of the organ in question
in a small laboratory animal before plunging into human pathology. In
doing this he will learn what is potentially possible. It is only when a
person has gained perspective in this way that he is really in a position to
appreciate his problems and his degree of accomplishment.
2.9. Special Problems with Tissue Cultures and
Cell Suspensions
One might think that tissue cultures with their exposed cells would
be the easiest of all tissues to preserve well, but this has not proven to
be the case. Some of the difficulties originally encountered no doubt
resulted from "polymerization damage" which is particularly prone to
affect exposed cells when conventional methacrylate embedding is employed (Chapter 4.8). But it should be pointed out here that tissue culture media no doubt behave rather like serum and tissue fluids. As has
previously been discussed, these act powerfully to destroy the desirable
qualities of osmium tetroxide fixatives so that vigorous flushing is necessary.
Thin sheets of tissue culture cells may prove difficult to see when it
comes time to orient blocks for sectioning. They can be stained with eosin
or, better, a basic dye such as toluidine blue while they are being
dehydrated which will facilitate subsequent handling.
In the case of cell suspensions, extreme dilution in a very large volume
of fixative with agitation may improve preservation. However, it has
several times been reported better to centrifuge suspended cells into a
TISSUE CULTURES AND CELL SUSPENSIONS
31
indeed, every pathologist recognizes them to a degree at the level of
conventional microscopy. Where possible, therefore, efforts should be
made toward obtaining juvenile or young adult tissue.
The human, after all, is a large animal with consequently much more
and much denser connective tissue in most places than a mouse or a rat.
Thus, tissue which preserves easily when taken from a small animal may
present serious problems when removed from humans.
Although this section may seem discouraging to those who would do
human pathology, this field promises particularly rich rewards, and ways
to success in particular situations are being found and will be found. One
should not be unduly discouraged if one's first efforts are dismally disappointing. It is certainly advisable for the novice to have a taste of success first by studying the normal morphology of the organ in question
in a small laboratory animal before plunging into human pathology. In
doing this he will learn what is potentially possible. It is only when a
person has gained perspective in this way that he is really in a position to
appreciate his problems and his degree of accomplishment.
2.9. Special Problems with Tissue Cultures and
Cell Suspensions
One might think that tissue cultures with their exposed cells would
be the easiest of all tissues to preserve well, but this has not proven to
be the case. Some of the difficulties originally encountered no doubt
resulted from "polymerization damage" which is particularly prone to
affect exposed cells when conventional methacrylate embedding is employed (Chapter 4.8). But it should be pointed out here that tissue culture media no doubt behave rather like serum and tissue fluids. As has
previously been discussed, these act powerfully to destroy the desirable
qualities of osmium tetroxide fixatives so that vigorous flushing is necessary.
Thin sheets of tissue culture cells may prove difficult to see when it
comes time to orient blocks for sectioning. They can be stained with eosin
or, better, a basic dye such as toluidine blue while they are being
dehydrated which will facilitate subsequent handling.
In the case of cell suspensions, extreme dilution in a very large volume
of fixative with agitation may improve preservation. However, it has
several times been reported better to centrifuge suspended cells into a