8.2. The Glass Rod Granuloma [107]. The glass rod granuloma,
described by Vogel, reflects the chronic proliferative
inflammation. Of the newly formed connective tissue not
only wet and dry weight, but also chemical composition
andmechanical properties can bemeasured. Procedure. Glass
rods (6mm dia, 40mm length) with rounded ends can
be made in flame. Rods are sterilized before implantation.
Male Sprague-Dawley rats (130 g) are anaesthetized, the back
skin shaved and disinfected. From an incision in the caudal
region, a subcutaneous tunnel is formed in cranial direction
with a closed blunted forceps. One glass rod is introduced
into this tunnel finally lying on the back of the animal. The
incision wound is closed by sutures. The animals are kept in
separate cages. The rods remain in situ for 20 or 40 days.
Treatment with drugs is either during the whole period or
only during the last 10 or 2 days. At the end, the animals are
sacrificed under CO2 anesthesia. The glass rods are prepared
together with the surrounding connective tissue which forms
a tube around the glass rod. By incision at one end, the glass
rod is extracted and the granuloma sac inverted forming
a plain piece of pure connective tissue. Wet weight of the
granuloma tissue is recorded and the specimens are kept in a
humid chamber until further analysis. Finally, the granuloma
tissue is dried and the dry weight is recorded.