Background: The use of cytological methods in the diagnosis of malignant lesions of the respiratory tract has been generally acclaimed as one of its most successful applications. Flexible fiberoptic bronchoscopy revolutionized respiratory cytology. as bronchial brushings. broncho-alveolar lavage and bronchial forceps biopsy became more easy. https://www.herbsdailyes.shop/product-category/b1-vitamins-thiamine/