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Using stained acryl latex-injected techniques, the arterial circle of the brain in Acomys cahirinus Desmarest was studied. Results revealed an important individual variability of investigated structure. Three morphological variants were found: (1) the lack of typical arterial circle – opened in front and the back side, (2) partial opened at the back side, (3) completely closed arterial circle. This finding is opposed to many species of mammals, including rodents, and especially laboratory mouse. In our point of view, it seems to be a specific character. [ABSTRACT FROM AUTHOR]

Summary Using the thiocholine method and histological techniques, the topography and morphology of cardiac ganglia in midday gerbil, Egyptian spiny mouse, chinchilla laniger and pigeon were studied. The results demonstrated that cardiac ganglia in all investigated species are embedded in epicardial fat. They formed plexo-ganglionic structures. Each of them composed of many ganglia (from seven up to 36) different in size and shape, and interconnected by fascicles of nerve fibres. Comparative analysis showed that the density of neural network and cell aggregations was different in individual species. The richest plexo-ganglionic structure was in pigeon. It was organized in three plexo-ganglia with an average of 30 ganglia. The largest one was located along the anterior interventricular sulcus. The cardiac ganglia of investigated mammals were localized mainly on the epicardium of atria; in Egyptian spiny mouse and chinchilla laniger on the ventral surface of right atrium, but in midday gerbil on the dorsal surface of left atrium. Moreover, in midday gerbil and Egyptian spiny mouse the little plexo-ganglionic structure on the ventricle were noticed. Additionally, in midday gerbil the single nerve cells might be observed between cardiac muscle of atria. It can be said that, the strongly developed cardiac plexus in pigeon is probably connected with his behaviour and functional properties of the heart. The arrangement of neurones in cardiac ganglia of all examined mammals was uniform over the whole surface of the sections, while in the pigeon, neurones were located mainly in the peripheral part of the ganglion. [ABSTRACT FROM AUTHOR]

Investigations were performed on 10 adult individuals of chinchilla ( Chinchilla laniger), midday gerbil ( Gerbillus gerbillus), rabbit ( Oryctolagus cuniculus), guinea pig ( Cavia porcellus) and Egyptian spiny mouse ( Acomys cahirinus). The animals were killed with ether anaesthesia and injected with coloured acryl latex through the abdominal aorta or left heart ventricle. The heads of the animals were fixed in formalin and after decalcification in 5% HNO3, injected arteries of the base of the brain were exposed. The different types of arterial circle of the brain in investigated species were observed. The open type with morphological asymmetry in the anterior part was found in chinchilla. It depended on an unusually strongly developed anterior cerebral artery at the right side. In the midday gerbil the most common form was the closed type of investigated circle, with a lack of typical communicating artery posterior. The morphological asymmetry of the anterior part of the circle without fully developed anterior cerebral artery was found in the rabbit. Typical, the closed type of investigated structure with little individual variability was observed in guinea pig. The most individual variability connected with anterior and posterior part of the Willi's circle was found in the Egyptian spiny mouse where it was difficult to describe the typical arterial circle of the base of the brain. [ABSTRACT FROM AUTHOR]