Methods for Fish Biology

Chapter 7: Histological Techniques

David E. Hinton


Strictly speaking, histology is the study of tissues, especially those minute parts beyond the reach of the naked eye. With a thorough prior knowledge of normal anatomy, the investigator uses histological analysis to detect alterations in tissues and organs (Hinton and Couch 1984). The scope of this chapter encompasses techniques necessary for the study of tissues and, to a lesser extent, cells.

Despite the inherent subjectivity of conventional morphologic findings, histology can be a powerful tool for biological assessment. For example, sections through entire adults of small fishes and through fry of larger species may be mounted on individual histological glass slides, from which general information may be obtained about a variety of tissues, organs, and organ systems (Couch et al. 1974; Couch 1984). Perhaps no other approach yields information simultaneously on so many different body sites. Histological analysis is commonly used in fisheries-related sciences to evaluate normal and pathological embryonated eggs and developing tissues (Hisaoka 1958; Rosenthal and Alderdice 1976; Daye and Garside 1980), normal (Ashley 1975; Ellis et al. 1978) and pathological anatomy related to diseases (Mawdesley-Thomas 1972; Ribelin and Migaki 1975; Roberts 1978), effects of toxicant exposures (Meyers and Hendricks 1985), nutrition (Halver 1972), carcinogenicity (Hoover 1984), and other aspects of the internal well-being of fishes.

Routine histological sections do not easily lend themselves to quantitation, although quantitative morphometric or stereological techniques are available that permit statistical analysis of histological data (Elias and Hyde 1983). Initial histological screening may steer the biologist to potentially instructive sites for subsequent, more quantitative, physiological or biochemical tests, ultimately providing a correlation of structure with function (Hinton and Couch 1984). The partial listing of major references for fish histology given in Table 7.1 indicates the types of information obtained by histological techniques.