The effects of ZnSO4 irrigation on mouse nasal respiratory epithelium (NRE) and subsequent responses of the tissue were studied at the light and electron microscopic levels in two different strains of mice (C57B1/6J and SWR/J).

The most marked effect of the ZnSO4 took the form of necrosis and sloughing of surface cells in both strains one-half day after ZnSO4 irrigation. This treatment caused maximal change in a different cell type in each of the two strains. Ciliated cells were most noticeably affected in the C57B1/6J strain, secretory cells in the SWR/J strain. Subsequent manifestations of recovery differed accordingly in each strain. In the C57B1/6J mice numerous dividing surface cells and large areas of tall nonciliated and ciliating cells were prominent two to five days after treatment. Secretory cells appeared normal but were reduced in numbers during this time, indicating that they were also affected by the treatment. The NRE of this strain was normal by the fourteenth day following treatment. The NRE of SWR/J animals, on the other hand, contained no visibly dividing cells and no large areas of nonciliated cells during the first four days following treatment, although a few ciliating cells were present at this time. The secretory cell population in these animals was normal after five days but individual cells deviated from normalcy by containing numerous dilated cisternae of rough endoplasmic reticulum which persisted in the secretory cells during the remainder of the experiment.