F. Stan

Comparative Study of the Liver Anatomy in the Rat, Rabbit, Guinea Pig and Chinchilla

In liver surgical and histological research, small rodents are the most used experimental models. Although the small animals liver is typically lobulated and its macroscopic appearance do not resemble that of the compact human liver, a high degree of lobulation equivalence, allow the use of small rodents in biomedical research. The macroscopic anatomy of the liver of the rat, rabbit, guinea pig and chinchilla was studied from a comparative standpoint. The topography, lobulation and the connection elements of the liver were examined by detailed in situ observation and explanted liver of forty specimens. The rat liver (Hepar) consists of four distinct lobes of different size: the left lateral lobe LLL (Lobus hepatis sinister lateralis), the median lobe ML, the right lobe – RL (Lobus hepatis dexter) and the caudate lobe CL (Lobus caudatus). The largest lobe was the median lobe. The rabbit liver consists of five lobes: left lateral lobe LLL, left medial lobe LML (Lobus hepatis sinister medialis), right lobe RL, quadrate lobe – QL (Lobus quadratus) and caudate lobe CL. The most developed lobe was the left lateral lobe. The caudate lobe had a very narrow attachment on the hilar region. The guinea pig liver show six lobes: left lateral lobe LLL, left medial lobe LML, right lateral lobe – RLL (Lobus hepatis dexter lateralis), right medial lobe – RML (Lobus hepatis dexter medialis), quadrate lobe QL and caudate lobe CL. The largest lobe of this specie was the left lateral lobe. In chinchilla liver showed four lobes like in the rat. In the rats the most developed hepatic ligament was the falciform ligament (Lig. Falciforme hepatis) which spans from xyphoid process of the sternum and diaphragm to the liver, beginning at the interlobular fissure. The coronary ligament (Lig. Coronarium hepatis) was well developed in all rats. Interlobular ligaments connect the left lateral lobe with the upper caudate lobe. In rabbits, guinea pigs and chinchillas the connection elements were represented by the falciform ligament, coronary ligament, right (Lig.triangulare dextrum) and left triangular ligaments (Lig. Triangulare sinistrum), hepatorenal ligament (Lig.hepatorenale) and hepatoduodenal ligament (Lig. hepatoduodenale) with varying degrees of development. Based on detailed study of the macroscopic anatomy of rat, rabbit, guinea pig and chinchilla a proper experimental model in liver research, could be assessed. In this regard, the vascular anatomy of the liver in the mentioned species is of a great importance and it is subject of another report.

A Comparison Between the Macroscopic Anatomy of the Cecum in Laboratory Rat and Guinea Pig

Controlled food and maintenance conditions cause both functional and anatomical adaptations of digestive system. The rat and guinea pig, used both as experimental models and as pets, shared common controlled environmental conditions. The two species were exposed during the generation to artificial conditions rather that natural ones. The effects of these conditions on the macroscopic anatomy of the cecum have been documented.

Morphohistochemical studies of the bowel segments in the nutria.

A number of 10 nutria (Myocastor coypus) cadavers from private farms of Cluj; sacrificed as a necessity; were studied. Besides the morphological observations were also performed some histochemical; and histoenzymological observations at duodenum; jejunum - ileum and colon level; in order to emphasize so me indices concerning the cytoplasmatic basophily of e nterocites; RNA presence; absorption process; and a lso secretion product of caliciform cells.