It is difficult for a teacher to accept the fact that not all of the information in his or her field is a necessary part of the armamentarium of the student. This holds for histologists, and for that matter, pathologists, biochemists, and ophthalmologists. It may especially hold for those who were trained during exciting periods in the history of their discipline. In the past two decades, information in every basic medical science has increased greatly, perhaps exponentially, and the basic science curriculum has been compressed to the point where the medical student can reasonably be expected to acquire only a superficial knowledge of anyone of these sciences. Hence the information provided must be carefully selected, effectively presented in retainable doses, and useful for understanding material to be presented later in the curriculum and for the solution of clinical problems. In the compact courses of today, the presentation of only enough data to support basic working concepts of structure and function is appropriate. Additional factual information consti­ tutes trivia, which in our opinion interferes with effective development, reten­ tion, and use of the concepts. This philosophy has been the basis for the preparation of this book. Consistent with this philosophy, the text is brief, and the content has been carefully examined for its appropriateness to the needs of the medical student.