Abstract
Various dissection guides and published articles both in paper format and as computer based supports exist for autopsy procedures and tissue sampling and concern a variety of species and organ systems. For staff working routinely as pathologists or necropsy room technical staff, they provide a good grounding in the basics for dissection and preparation of specimens for subsequent histological examination. They are also evidently of additional use in the case of more skilled staff as a source of reference and for consultation for those who frequently perform autopsises.
The collection and preparation of histological specimens for the rodent heart (rat, mouse and hamster) is relatively simple and representative areas of the organ can easily be obtained and evaluated, although the overall number of sections to be examined and the orientation of the specimens on routine studies is still a question of some debate.
For this CD-Rom, the authors (GlaxoSmithKline, EPL and NIEHS/NTP) have selected the dog and non-human primate as the subject for a guide concerning the collection of the heart. In the case of the routine pathological examination of the dog and non-human primate heart for toxicology studies, the gross examination of the heart and its’ dissection and sampling to obtain representative areas for a complete review of any possible changes both macroscopic and microscopic is more complex. There has tended to be two schools of thought with either a minimalist or maximalist approach to sampling and examination, although in view of the emphasis placed upon cardiac toxicity by the authorities at the present time, the latter approach is now certainly the more employed.
In this CD-Rom, the organization of the guide is such that it will enable users to pick and choose exactly how they wish to proceed with the examination and sampling of the heart from both the dog and non-human primate. The CD-Rom itself is extremely user-friendly and after accessing the program proposes the choice between the dog and non-human primate. For both species the organization for the menu is the same. The menu itself is a series of chapters in a logical sequence starting with the gross appearance of the heart (360° rotation of the heart with both lateral and vertical aspects, external identification, internal identification, tissue trimming, histology, macroscopic and microscopic pathology, publications and references).
Each section of the menu begins with a series of photos enabling the user to access the different subsections. For the 360° rotation, the lateral and vertical images are of the complete heart shown in 3 dimensions which can be rotated by the use of arrows. For the internal and external identification the important areas within the heart are identified either by selecting the area presented on a photo-representation of the organ or by selecting the area from a list provided with the image. The following section in the menu concerns tissue sampling and trimming to collect the requisitre areas of the heart which will be subsequently examined histologically. The authors are to be congratulated on the clear step by step series of images with accompanying explanations on how to remove the heart from in situ, and to subsequently orientate the heart and identify the areas for sampling. This is particularly the case for sampling of the SA node which in many cases can be a hit or miss affair. The subsequent selection of areas of left and right ventricle, interventricular septum and the SA node itself followed by the trimming details to give representative samples for blocking –up are easy to follow and well documented with both clear images and simple text instructions. Technical staff who have seen this CD-Rom found it to be of great value as both a possible training tool and reference source.
The histology menu of the CD-Rom follows logically on from the tissue trimming part with representative histology slides prepared of the areas shown from trimming, including step sections on how to locate the SA node. It is possible to zoom onto selected areas again simply by selecting the relevant keys.
In the macroscopic/microscopic pathology menu, the authors have selected a comprehensive series of cardiac changes for the reader to consult. These cover the majority of pathologies which may be encountered in both the species selected, although it is obviously not a complete atlas of cardiac pathology, which is not the point of this CD-Rom. In an updated version, or even a separate CD-Rom this could obviously be further extended or developed.
In the non-human primate, the CD-Rom also includes a section related to morphometric analysis of the heart with an introduction to techniques which can be applied to this organ, the Cavalieri method for measurement of volume is that selected for presentation within the non-human primate menu. The actual format is easy to follow and allows the reader to gain a clear insight into the histological processes involved and the subsequent data capture.
The final menu consists of a section of publications and references which are subdivided into general, pharmacology/electrophysiology, spontaneous and experimental pathology and drug or chemically induced pathology. The authors have selected a number of key articles of which many have recently been published which give a good introduction to the subject of cardiac toxicity and pathology in general. There is an added bonus on the CD-Rom with an internet link in the last section on drug induced pathology to a series of presentations given at The Toxicology Forum 30th Annual Summer Meeting in 2004. In my copy of the CD-Rom however I was unable to access all of them, but this may have been an isolated problem.
To prepare this CD-Rom, the authors have obviously consecrated a great deal of time and effort. As mentioned above, the sampling and examination of the heart in the larger animal species for toxicology studies has often been according to the individual preferences of laboratories, although some standardization does now exist. This CD-Rom with its’ clear outlines and logical presentation can serve as a basis for standardized protocols to sample the heart in the dog and non-human primate and may also be used as a teaching aid and computer accessible aide-memoire for technical staff within the necropsy room, and it is thoroughly recommended to all pathology staff. It will be interesting to know if the same authors have any intention of producing a similar CD-Rom for other organs in the same species; one for which the basics of sampling and tissue preparation could be of interest is the brain. For complimentary copies of the CDs, contact Robert R. Maronpot, NIEHS, 111 Alexander Drive, MS B3-06, Research Triangle Park, NC 27709 or