Although a growing number of studies employ small fish gonadal histopathology in the assessment of endocrine disrupting compounds (EDCs), the literature has lacked a comprehensive presentation of the basic biological function, the normal histology, and the histopathology of small fish gonads. In response, this book sets forth recommended standards that facilitate accurate, meaningful interpretation of the findings from aquatic bioassays and field observations of a variety of commonly studied fish species, with special emphasis on the routinely employed small laboratory fish, i.e., the zebrafish, medaka, and fathead minnow.
The authors, leaders in the field of small fish gonadal histopathology, have reviewed and synthesized more than 1,200 publications and reports to help identify and clarify inconsistencies in the field. Among the topics covered are:
- Basic fish biology and fish sexual reproduction
- Male and female fish gonad development and histopathology
- EDC–mediated effects and the relevance of parameters determined for evaluating EDC–mediated effects
- Methods for histopathological processing
- Evaluation and quantification of effects
- Experimental design and statistics
Each chapter includes references to the primary literature to facilitate further research. The appendix offers step–by–step guidance for fish preparation and microdissection of organs.
Small fish such as zebrafish, medaka, and fathead minnows are increasingly used in risk assessment studies and for the registration of chemical, agricultural, and pharmaceutical compounds. This book represents the state of the art on small fish gonadal histopathology, providing the right amount of anatomical and physiological background to help readers understand and interpret xenobiotic–induced changes in gonadal histology in a mechanistic context.
2 Fish Species of Interest.
2.1 Fathead Minnow (Pimephales promelas).
2.2 Medaka (Oryzias latipes).
2.3 Zebrafish (Danio rerio).
2.4 Other Fish Species.
3 Sexual Determination, Differentiation, and Gonadal Development.
3.1 Primordial Germ Cells in the Primordial (Primary) Gonad.
3.2 Reproductive Strategies.
3.3 Differentiation of the Primordial Gonad into Ovary or Testis.
3.4 Gonadal Duct Formation.
3.5 Endocrinology: Influence on Gonadogenesis.
3.6 Critical Period of Sexual Differentiation in Developing Fish.
3.7 Bi–Potentiality of Germ Cells in Adult Fish.
4 Female Gonad Anatomy and Morphology.
4.1 Gonadogenesis: Ovary.
4.2 Hypothalamic Pituitary Ovarian Axis.
4.3 Cellular Structure of the Ovary.
5 Male Gonad Anatomy and Morphology.
5.1 Gonadogenesis: Testes.
6 Endocrine–Disrupting Compounds.
6.1 Individual Effects.
6.2 Effects Associated with Exposure to Specific Compounds or Compound Classes.
6.3 Population Effects.
7 Determination of Effects of Exogenous Hormones and Endocrine–like Active Compounds.
7.1 Histological Processing: Microdissection versus Whole–Fish Sectioning.
7.2 Optimal Tissue Preparation and Histological Techniques.
7.3 Plane of Gonad Sectioning for Optimal Organ Representation.
8 Evaluation of Effects in Fish Gonads.
8.1 Qualitative (Semiquantitative) versus Quantitative Evaluation.
8.2 Gonadal Staging in the Testis.
8.3 Gonadal Staging in the Ovary .
8.4 Qualitative Assessment of Histopathological Changes.
9 Experimental Design and Statistics.
9.1 Basic Considerations in Experimental Design.
9.2 Variables to be Determined and Their Inherent Biological and Mathematical Characteristics.
9.3 Prerequisite Statistical Concepts.
9.4 Statistical Tests and Testing Situations Encountered Routinely.
Appendix: Fish Preparation and Microdissection of Organs.
A.1 Fish Preparation.
A.2 Microdissection of Organs.
A.3 Tissue Fixation.
A.5 Tissue Sectioning.
A.6 Sample Mounting.
A.7 Tissue Slide Staining.
A.8 Final Processing.
Heiko O. Krieger, MSc, is a scientific research assistant and PhD student in the Human and Environmental Toxicology Group, Faculty of Sciences of the University of Konstanz, Konstanz, Germany.