VM8054 Veterinary Histology

Course Introduction

Author: Dr. Thomas Caceci

VM8054 is an introductory course in animal histology and microscopic anatomy of organs. For the most part, it will deal with cells and tissues from mammals. This course is intended to give you enough experience with the material so that at the end of it you should be able to identify normal tissues and organs prepared by standard methods for light microscopy.

While VM8054 serves principally as a conceptual framework for later study in the DVM curriculum, it can't and shouldn't be viewed solely in that light. Some of you, inevitably, will decide that your career path lies in research, teaching, or academic pursuits. Some of the course material is intended to address this segment of the class, and I hope that those people find the course exciting and interesting enough to consider future study in microscopic anatomy. Those who are primarily clinically oriented will also derive benefit from some of the less-directly-applicable information, too; it will provide a basis for the "why" of certain pathological changes, not just the "what."

Course Organization

The course is organized into 30 classroom lectures/demonstrations, and 15 laboratory sessions. A list of the topics to be covered in each lecture/lab is provided. Laboratory exercises are intended to take two hours apiece.

I will also scheduled several optional review sessions for those students who feel they are in need of some extra time to discuss the topics of the week. These are not "official" sessions. The times and places of such meetings will be at mutual convenience, and are subject to ad hoc revision. Generally I try to schedule review sessions for Friday afternoons, but times vary to avoid conflicts with other courses. At these one-hour sessions, I will be available to answer questions about the material covered in the course up to that point in an informal setting. You can, however, always get an answer to specific questions you may have by contacting me directly. The easiest way is via e-mail. See Contacting Me for details.

A Historical Perspective

Histology is a subdiscipline of anatomy. Because it depended on advances in optics, it didn't really begin to be important as an independent field of study until the mid-18th century or so; the period of most rapid growth was the late 19th and early 20th centuries, which saw the simultaneous perfection of optical instruments, the development of the coal-tar dye industry, and the introduction of efficient tissue preparation techniques. Most of the structures you'll see in this course were discovered between about 1850 and 1950, using microscopes not too different than the ones you'll use in the course. The development of the electron microscope after WW II led to a renaissance of interest in structural biology, and studies done with it enormously enhanced the understanding of cellular architecture and its relationship to cellular function. For this reason, in the lab exercise I'll frequently refer to studies performed with the EM. It is necessary to include ultrastructural information (even though you will not be using an EM yourselves) because it's largely on such work that modern concepts of how cells are made and operate are based.

The word "histology" comes from the Greek roots histos, a web or tissue; and logos, knowledge. Strictly speaking, "histology" is confined to the structure of the "tissues" of the body—epithelium, connective tissue, muscle, and nervous tissue. The term "microscopic anatomy" refers to the minute structure of actual organs, which are composed of tissues. In practice, however, this distinction is very blurry, and the term "histology" is commonly used for both of these subdisciplines. It will be so used in this course.

What You Will See

Generally speaking, you'll deal with normal tissues; except in a very few cases, I'll avoid showing you pathological material. This course is a foundation for later work in pathology, and since successful diagnostic interpretation of pathological change depends on a thorough understanding of what is within the range of normal, my principal aim is to give you good mental images of what the various types of normal tissue look like. These will serve as standards of comparison that should help you understand diseased material in later parts of the DVM curriculum. The few examples of abnormal tissue I've included serve to highlight some important point.

Structure-Function Correlations

The interchangability of structure and function is the heart of the course and its main theme: anatomy and physiology are the same thing, seen from different perspectives. Anatomy can be considered the structural representation of physiology, and physiology the functional expression of the capabilities of structure. As important as it is, there is not nearly enough time to present more than the barest outline of the clinical implications of what you'll see. I do hope the course will help you to understand something of the relationship, though, and that the physiology and clinical material you'll be taught in later course work will make more sense because of what you get here. In the interests of time and accuracy I'll sometimes refer you to other members of the faculty whose expertise is greater than mine if you are interested in going deeply into a given topic, especially clinical correlations.


The course presumes no previous work beyond the level of introductory biology, and the only prerequisite is that you be enrolled in the DVM program. Although I recognize that many first year veterinary students have had exposure to histology (either in a formal course or through specialized experience in work or research) nevertheless many have not; and so the course deals with basics. I hope those of you who have had some or all of this material before will consider this course a useful review, and that you'll be able to help some of your classmates who haven't had the benefit of prior information.

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VM8054 Veterinary Histology