Abstract
Heart Trimming Protocol of the Laboratory Rat is an interactive tutorial on CD-ROM that should prove informative and useful to both academic and industry pathologists as well as their respective students and technical associates. The Heart Collection Protocol of the Laboratory Dog and Monkey is a set of tutorials on a single CD-ROM that is a perfect companion to the Heart Collection Protocol for the Laboratory Rat CD-ROM. The tutorials are constructed very similarly. The tutorials present in a concise and image-rich fashion a standardized methodology for gross sampling and processing of the rat, dog, and nonhuman primate hearts for histologic sectioning and microscopic examination. The tutorials are organized into units that, when viewed in sequence, take the reader from basic cardiac anatomy to specific trimming instructions to low- and high-magnification microscopic images of annotated normal and pathologic cardiac histology. The protocols for the dog and monkey are presented individually on the same CD and have similar formats to the rat tutorial. Menus allow one to skip around in the tutorials for quick reference to specific units. The “3D Heart” unit allows 360° rotation of the heart in short- or long-axis views. Static images in the “External Identification” unit permit delineation and identification of major anatomic landmarks with appropriate movement of the cursor. “Trimming and Processing” is presented in animation and demonstrates for the rat a gross trimming method that produces, in a single sample, a complete longitudinal section of the heart that includes segments of atria and ventricles as well as right and left atrioventricular and aortic valve cusps. An alternative gross trimming method is outlined for the rat in the “Isaacs Method” and proposes sections of the base and apex of the heart in longitudinal section coupled with a midventricular myocardial cross-section. “Tissue Trimming” units for the dog and monkey are also presented in animation with regular pauses built into the tutorial to allow the student to complete the trimming procedure in synchrony with the lesson. Individual sampling protocols for routine evaluation of the complete heart in four blocks for the dog and three for the monkey are outlined. The protocol for the dog includes serial sampling of the right atrium at the sulcus terminalus to allow evaluation of the Sinoatrial node. The “Histology Identification” and “Histology in Focus” units present low- and high-magnification images, respectively, of normal cardiac histology with appropriate labeling of subgross and tissue components. One of the useful additions to this revision of the rat tutorial that might prove informative to those who do not have occasion to look at rat hearts on a regular basis is a “Pathology” unit. This is also replicated in the dog and monkey CD and consists of multiple electronic pages of microscopic images of common myocardial lesions in each tutorial. The dog and monkey CD also includes significant numbers of images of common artifacts and incidental findings. The pathology unit for the monkey section uniquely begins with a textual description of special handling needs and potential artifactual outcomes that could be applied to the heart of any species. The monkey tutorial also contains an interesting and unexpected unit (entitled “Morphometric Analysis”) describing and illustrating the Cavalieri estimator of volume stereological method as applied to the nonhuman primate heart. Although this method is illustrated on gross cross-sections of the fixed heart, the authors acknowledge that the principles and practice of the method also apply to histologic tissue sections. All of the tutorials end with a list of relevant references to journal articles, texts, and symposia for further edification.
The digital imagery in these tutorials is excellent and should allow easy translation of the learning in these lesson sets to the histology laboratory. Either of the two rat protocols could easily be adapted as a standard trimming protocol for studies that include a routine or even targeted (i.e., heart valves) histologic examination of the murine heart. The dog and monkey sampling paradigms should also prove useful to both diagnostic and toxicologic pathologists alike.