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

Non-Invasive Assessment of Sentinel Lymph Nodes That Drain the Tumoral Mammary Glands in Female Dog

Introduction: Mammary gland tumours occupy a significant place in the pathology of this species. Female dogs that are not spayed after their first heat cycle have a higher predisposition of developing mammary tumours. Most tumours metastasize at distance via the lymphatic system. In these conditions, the sentinel lymph nodes of the mammary glands must be assessed prior to surgical treatment. Aims: Considering the insufficient usage of non-invasive investigative methods of the sentinel lymph nodes, the aim of this study is to describe the sonographic anatomy of the lymph nodes that drain the mammary gland tumours in female dog. Materials and Methods: Twelve dog females presenting tumours of the cranial and caudal abdominal mammary glands (A1 and A2), inguinal mammary gland (I) and cranial thoracic mammary gland (T1) were examined (group I). In addition, a control group composed of eight dog females was used (group II). The axillary and superficial inguinal lymph nodes were evaluated using an algorithm composed of gray-scale ultrasound, Doppler technique, contrast enhanced ultrasound (CEUS) and real time elastography. Surgical excision of the sentinel lymph nodes was performed and samples for histopathological examination were taken. Results: The following ultrasonographic findings revealed on gray-scale examination were suspected for the metastatic infiltration: hypoechoic pattern, round shape, hillus absence and heterogenicity. Doppler technique showed an aberrant and mixed vascularisation of the lymph nodes, while the CEUS revealed incomplete enhancement of lymph nodes parenchyma. On real time elastography, the presence of blue areas in more than 50% from the lymph nodes parenchyma led us to conclude that the lymph node stiffness was caused by metastatic infiltration. Histopathological examination confirmed the presence of the metastatic infiltration in 97% of the examined lymph nodes. Conclusion: The algorithm composed of gray-scale ultrasound, Doppler technique, CEUS and real time elastography proved to be efficient in diagnosing the metastatic infiltration of sentinel lymph nodes of mammary gland. Further studies are needed to validate the proposed algorithm.    Â