Regeneration potential of the submandibular gland after transplantation. An immunohistological and scintigraphic study

The aim of this study was to evaluate the regeneration potential of the submandibular gland and the associated morphological and functional impairment after a transient warm ischemia as a result of submandibular gland transfer in humans. 42 rabbits were used for the study. After 1.5 h of transient ischemia, submandibular glands were studied histologically in the following 14 days, one month, two and four months in 32 rabbits. Additionally, the glands were functionally evaluated after one and four months in eleven of these rabbits. Ten rabbits were used to establish the scintigraphic method. In the evaluation of the results unpublished data derived from a previous study by our group has also been considered. The Ki-67 index showed a significant increase of the proliferating rate reaching a peak after 14 days (p = 0.006) and still evident after four months involving mostly the terminal ductal system. There was only a slight increase in the tracer uptake of ischemic glands after one month and a more pronounced one after four months. It was concluded that initial loss of acinar cells by 1.5 h of ischemia released a regeneration process which stabilised after 14 days but continued throughout the whole time of the study. These results correlate with clinical observation in patients with submandibular gland transfer for the treatment of keratoconjunctivitis sicca and explain the alternating secretory function observed within the four months following surgery. Scintigraphy has been found to play a limited role in the evaluation of the regeneration process.