When living cells or tissues are reduced to very low
temperatures cell and tissue destruction can occur.
The controlled destruction of diseased tissue in clinical
patients by the application of cold is termed - CRYOSURGERY -
in which Kryos in ancient Greek means frost.
Cryosurgery is a clinicEil technique applied to diseased
animal tissues and particularly to malignant tumours. The
diseased tissues are subjected to direct sub-zero temperatures.
Following treatment the tissues necrose and are sloughed.
The subsequent healing is by secondary intention.
Cryosurgery is being used increasingly in human and veterinary
practice and many questions remain to be answered about the
destructive power of cryosurgery on living tissue and the
fate of non-diseased tissue adjacent to a cryosurgical
There is a considerable amount of recorded data concerning
tissue damage, death and repair following several types of
injury including the effect of freezing. This present
study was designed to observe the effect of controlled
freezing on living tissues to cryogenic or cryo-destructive
temperatures, with particular reference to the healing
processes involved and the degree of tissue repair in
different areas of the cryo-lesion.
Skeletal muscle and peripheral nerves are frequently
frozen either intentionally or inadvertently, during
cryo-therapy of deeper lesions and it was considered
important to examine the effects of cold injury in these
The investigation is related to the histopathology
of the tissue changes during destruction, repair and
regeneration employing light microscopy and electron
Cryosurgery has been employed with success in the
treatment of lesions of the skin and adnexa in man and
some species of domestic animals but comparable results
have not been achieved in treating benign fibrous skin
tumours in the horse (Borthwick, 1970). There was a high
percentage of recurrence of neoplasms in cryosurgically
treated horse skin. The clinical problems of the surgery
of horse skin stimulated the third part of the investigations
reported in this thesis.