Saturated salt solution: a further step to a formaldehyde-free embalming method for veterinary gross anatomy.

In the field of veterinary anatomy, most of the specimens used in practical sessions are perfused with fixatives. Thus, they can be used for a longer time, reducing the number of animals for educational purposes. Formalin is the most commonly used fixative, consisting of a 37% formaldehyde solution. However, formaldehyde is a powerful irritant of the eyes and airways and is considered carcinogenic, causing nasopharyngeal cancer in exposed workers and professionals. In the present study, we explored an alternative method to avoid the use of formaldehyde in specimens used for gross anatomy practical sessions. We propose an inexpensive, non-toxic fixative that is available worldwide, such as sea salt. This method consists of a continuous perfusion of saturated salt solution for a period of 6-8 h, enabling drainage of the solution to avoid a weight increase of the specimen, and allowing salt to be retained in the tissue. The method is based on recirculation of the saturated salt solution instead of maceration. Perfused specimens retained their natural consistency and joint mobility, with no blood, resembling a piece of meat from the slaughterhouse. They could be used immediately without a maceration period, or stored in the fridge until use and then kept in a bath of saturated salt solution for future conservation. In the case of the former, no refrigeration was needed. The specimens did not have an irritating or offensive smell, and could be used for long sessions (several hours per day) and stored for long periods. However, the blood vessels used for perfusion determine the results: a less invasive approach (through common carotid arteries) gave good preservation of the musculoskeletal system, whereas more invasive access to cannulate the abdominal aorta and vena cava caudalis was required to achieve better preservation of the viscera. In conclusion, we propose that perfusion followed by immersion in a saturated salt solution is a good alternative method for the preservation of specimens used in the practical teaching of gross veterinary anatomy. It is a very simple and inexpensive technique, and is much healthier for users than traditional formalin. Moreover, specimens can be preserved for prolonged periods, and maintain a similar appearance and consistency to fresh material.

Development of the mesonephros, metanephros and gonads in the foetal dog.

We describe the chronology of the development of the renal system and gonads of 19 greyhound foetuses. The smallest specimens were embedded in paraffin wax and were sectioned serially at 10 microns; the rest were sectioned at 50 microns in an LKB 2250 PMV cryomicrotome. Selected sections were stained with haematoxylin and eosin. The mesonephros, metanephros and gonads were measured in drawings of the sections, using the area fraction programme of a Vids II image analyse.

Morphological and morphometric development of the stomach and intestine of the foetal dog.

We describe the chronology of development of the stomach and intestine in 18 greyhound foetuses. Using an LKB 2250 PMV cryomicrotome, we obtained corresponding series of sections (50 microns). Very small specimens were embedded in paraffin wax and sectioned at 10 microns. Selected sections were stained with haematoxylin and eosin. For measurement, the fractional area programme of a Vids II image analyser was employed.

Growth curve of the foetal dog and the morphometry of its internal cavities and organs.

In the present study we determined the foetal growth curve of the greyhound. Using an LKB 2250 PMV cryomicrotome, we studied selected sagittal sections from 15 foetuses of the same breed of dog and described the expansion and development of the thoracic and abdominal cavities, the lungs, the liver and (in part) the heart and the thymus. Drawings of the sections were measured by means of a Vids II image analyser and its fractional area programme.