Abstract
This thorough atlas, which compares the anatomy of the mouse and the rat, has its origin in two posters and is definitely a book to recommend to researchers and technicians working with these species. A page at the beginning of the book describes the nomenclature and abbreviations used in the atlas, and I was pleased to see that they are taken from the Nomina Anatomica Veterinaria (fifth edition, 2005). The atlas is a soft-cover, spiral-bound book, which makes it easy to work with in the necropsy laboratory.
The atlas is divided into the following twelve sections, each of which each contributes a bulk of information:
Body regions: Detailed figures, with all the regions you could imagine, shown in the rat. One figure nicely illustrates and describes the anatomy relating to the cervicothoracic vessels and the jugular fossa, which could be a valuable help when conducting blood sampling from the external jugular vein.
Juvenile features and sex differentiation: Illustrative pictures showing the external differences between male and female mice and rats at different ages. These differences are shown on a neonate (age less than twenty-four hours) at day 5, 11, 21, and on an adult.
External features: Viewed from a dorsal and ventral aspect in both mice and rats (male and female). In addition, this section includes some nice drawings of both the palmar and plantar aspects of the feet.
Mammary glands: Fine illustrations showing the vast amount of mammary gland tissue that both the mouse and rat possess. The mouse has more extensive mammary glands, which extend the whole way up behind the ears and the shoulder (occipital, dorsal neck, and interscapular regions).
Structures of the head and neck: Detailed illustrations of the vibrissae, lacrimal and salivary glands, orbital veins and venous plexus, brain structures including detailed figures of the arterial and venous vasculature, and median section of the head. There is a nice illustration of the pharynx with a rostral aspect from the open mouth, and finally, the head and neck to the upper thorax is shown, including the heart and great vessels (ventral aspect). This is an impressive amount of information.
Heart, vascular tree, and respiratory tract: Very detailed figures of the lungs, heart, and thymus in relation to the position in the thoracic cavity and in relation to the ribs. The heart, aorta, vena cava, and other main vessels are illustrated from left, right, atrial, auricular, ventral, and dorsal aspects, covering nearly all possible situations. A footnote states that the paraconal interventricular artery in humans is called the left anterior descending artery, and ligation of this artery induces myocardial infarctions in mice and rats. Finally, in this section there are figures of the cervicothoracic organs, including the thoracic lymph nodes and the heart with the vascular tree.
Abdominal structures: Practical information is scattered in between the description of the figures, for example, that the pancreas is more compact and closely associated with the stomach and duodenum in the mouse, whereas in the rat the lobules/acini are scattered in the greater omentum and are not easy to distinguish from fat. These conditions make a total pancreactomy practically impossible in the rat. The cecum in the mouse can move more freely than in the rat, in which it is in a more fixed position as a result of a larger ileocecal fold.
Male urogenital apparatus: As stated in the preface of the book, emphasis is given to the details in the male’s urogenital apparatus, and this is indeed the case. If one is seeking specific information regarding the glandular structures associated with the urethra (including urethral recess) and the penis, just to mention some of the structures in the male genital organs, this is definitely a book to choose. In this section is also included a histology picture, namely, an interesting hematoxylin and eosin–stained median section of the penis to show the corpus spongiosum glandis and the os penis in detail.
Female urogenital apparatus: Here one can learn that the mouse has a uterus bicornis and the rat has a uterus duplex, with two cervical canals and a vagina simplex. It is also stated that females have preputial glands (I actually thought that these glands were called clitorial glands in the females, but now I understand that both terms can be used). A fine illustration shows how the round ligament of the uterus enters the vaginal ring.
Pelvic limb vessels and nerves: For the purposes of vascular procedures, detailed illustrations are given of the vessels and nerves. The muscles are vaguely outlined, which works well.
Structures of the tail: Useful hematoxylin and eosin–stained cross-sections of the tail at the level of the sixth caudal vertebra (mouse) and third caudal vertebra (rat) are illustrated at 20× magnification, a good help for those starting to read intravenous studies in these species.
Skeletal structures: The last section finishes the atlas with figures of the full skeleton of both species and illustrates topographical differences, which reflect that the rat has a greater musculature and physical strength. The very last figures are the skull and details of the teeth.
If I should mention one thing that could have been different; it would have been nice if the names of the structures were always placed on the same location on the page in both mice and rats. Doing so would make the comparison quicker to access.
Overall, I think the journey through this atlas with the comparative anatomy of the rat and mouse was interesting, and the book gives a lot of good information to the medical industry. In this industry, we are constantly challenged to find new structures, which researchers have found it interesting to investigate more thoroughly.