It is a viscous colloid containing antiseptic enzymes -LRB- such as lysozyme -RRB- and immunoglobulins that serves to protect epithelial cells in the respiratory , gastrointestinal , urogenital , visual , and auditory systems in mammals ; the epidermis in amphibians ; and the gills in fish .

It is a viscous colloid that contains antiseptic enzymes -LRB- such as lysozyme -RRB- and immunoglobulins that serves to protect epithelial cells in the respiratory , gastrointestinal , urogenital , visual , and auditory systems in mammals ; the epidermis in amphibians ; and the gills in fish .
