Histology as a tool in disease diagnosis

Histology is an important tool in fish disease diagnosis as it affords the comparison of normal structures or morphology of tissues against those from diseased fish. However, correct diagnosis and confirmation of changes associated with diseases require proper specimen processing and some degree of expertise in histopathology. The four basic types of tissues are: epithelial, connective, muscular and nervous. An organ is usually a combination of these four tissue types. It is important to remember that the histology or structure of an organ is always related to the function it performs