In vivo morphology and ultrastructure of thyroid autografts in rabbit ear chambers

Partial thyroidectomies were performed in half-lop rabbits. Small pieces of thyroid tissue were grafted into fully healed Sandison--Clark rabbit ear chambers. Thyroid grafts were observed directly through the compound microscope and sequential observations were recorded on photographic films and video tapes, with grafts remaining undisturbed within their vascular bed. Circulation within grafts was established within 3-5 d post-operatively, and between the second and fourth week pulsatile lymphatics loaded with lymphocytes could be observed within the grafts. Moreover, initial cellular infiltration, epithelial cell necrosis and regeneration have been recorded. Clear spaces or droplets observed within the colloid in vivo are considered to correspond to histological features long considered to be artefacts. This technique allows a non-intrusive approach to the study of the thyroid gland and thus can be used in studies of in vivo thyroid physiology, pharmacology, pathology and therapy.