Histological and mast cells evaluation after application of botulinum toxin type a in masseter muscles of rats

Botulinum Toxin Type A (BTX-A) has been largely used to reduce muscle strength of masseter and temporal muscles by producing a temporary weakening of their activity. This study aimed to evaluate the histological changes and the number of mast cells after the injection of BTX-A.In the masseter muscle of rats in the periods of 1, 7, 15, and 30 days. These muscles were stained with hematoxylin and eosin (HE) and toluidine blue (TBO). The presence or absence of an inflammatory process and necrosis were analyzed by HE in all area of the slide at 10X magnification. The number of mast cells was evaluated by counting 10 "hotspots" in the intra-muscular region on TBO-stained slides, 400X magnificati…