Conventional light and electron microscopic techniques failed to clarify
the cellular composition and derivation of spontaneous and induced,
intrasellar and transplanted pituitary adenomas in rats (1). In the present
work, electron microscopic immunocytochemistry was applied to evaluate five
adenohypo-physial tumors using a technique described by Moriarty and Garner
(2).
Spontaneously occurring pituitary adenomas (group 1) were harvested from
aging female Long-Evans rats. R-Amsterdam rats were treated with 2 x 1.0 mg
estrone acetate (HogivaI) s.c. weekly for 6 months. Pituitary adenomas in
excess of 30 mg were removed from these animals to make up the tumors of
group 2. Groups 3 and 4 consisted of estrogen-induced autonomous
transplan¬ted pituitary tumors MtT.WlO and MtT.F4. Group 5 was a
radiation-induced transplanted autonomous pituitary tumor MtT.W5. The tumors
of groups 3,4 and 5 were allowed to proliferate in host rats 6-8 weeks prior
to removal for processing. Tissue was processed for transmission electron
microscopy (glutaraldehyde fixation, OsO4 postfixation
and epoxy resin embedding), and electron microscopic immunocytochemistry (3%
paraformaldehyde fixation and Araldite embedding).