Histological changes in the trachea of the adult Wistar rat following exposure to cement dust

Abstract

BACKGROUND AND AIM: Cement dust is an atmospheric pollutant which poses a significant threat to the environment and humans. Previous studies have shown that cement dust causes bronchitis, chronic obstructive pulmonary disease, lung cancer and other lung diseases. Not much has been reported on cement dust exposure on trachea. Therefore, this present study was carried out to investigate histological changes in the trachea of Wistar rats following exposure to cement dust. METHODOLOGY: Twenty-four (24) Wistar rats weighing between 250g and 280g were divided into 4 groups of 6 rats per group. Group A rats were placed in a cement dust free chamber while Group B - D animals were exposed to cement dust dispersed from 5g (low dose), 10g (medium dose) and 20g (high dose) of cement, respectively via dust distributor glass-chamber of dimensions 32.5 cm3 in length, 32.5 cm3 in width and 16.5 cm3 in height for 1 hour daily for 30 days. The weights of the rats were taken weekly and the difference between them and previous weights were noted. At the end of the 30th day of exposure, the animals were euthanized under chloroform anaesthesia and the tracheae were harvested and processed for histological examination. RESULTS: The histological sections of the trachea of rats in Group A revealed normal lumen, mucous membrane, sub-epithelial areolar connective tissue, cartilage, muscularis layer and glands. There were observable histological variations in the tracheal architecture of the exposed rats (Groups B-D) which include mural oedema, sub-epithelial infiltrates of inflammatory cells, mucosal ulceration, and luminal haemorrhage. These injuries are consistent with usual histological findings in tracheitis. CONCLUSION: It was concluded that cement dust had histomorphological effects on the mucous membrane, lumen, muscularis layer and sub-epithelial areolar connective tissue of the trachea which are capable of compromising the health of the research animals.