Liver is the largest visceral organ in the body and has a paramount importance. Its multi-functional abilities make it absolutely necessary for survival. It performs numerous functions in a living organism and plays its role in various physiological and biochemical regulatory processes in the body. It is also the only organ that has the capability to undergo the phenomenon of regeneration in case of cellular injury induced by chemicals or surgery.
According to Craige (1948) Liver is the largest gland of the body. It is an extension of the gastro-intestinal track and connects with GIT to the common bile duct.It has two surfaces. The anterior or dorsal surface is convex while the posterior surface is concave and lies over the stomach. Liver is thickened in its dorsal portion and tappers to a thin ventral margin. The liver is incompletely divided into a right and a left liver lobe, each of which have anterior and posterior lobules. The right posterior lobule lies closely to the dorsal body wall and it accommodates right kidney in a depression called renal fossa. The gall bladder is a thin walled pouch located in a deep depression on the ventral surface of right anterior lobule. The quadrate lobe extends from the right lobe and is usually notched on its medial margin. The caudate lobe is small and well separated. The portal fissure is a large depression filled by the portal vein and it also contains some branches of hepatic artery. The liver is held in place by four ligaments namely falciform ligament, round ligament, coronary ligament and left triangular ligament.
According to Borley & Achan (2005) Liver plays a key role in several regulatory processes in an organism. It is involved in various metabolic pathways comprising variable interactions with proteins, carbohydrates and fats. Liver is the main site for gluconeogenesis, converts galactose and fructose into simple sugars (glucose) and stores complex carbohydrates (glycogen).It aids in the production of different types of proteins and has a role in the formation of urea. Numerous types of fats like phospholipids, cholesterol and lipoproteins are synthesized in the liver. Liver also uses different carbohydrates and proteins to form certain fats. Liver serves as a vault for the storage of several vitamins (A, B2 and D) and iron. It helps in the complex process of coagulation by aiding in the synthesis of several important coagulation factors including prothrombin, protein C, and factors VII, IX and X.Several hormones including oestrogen, aldosterone and cortisol are metabolized in the liver. It is involved in the metabolism of a number of drugs and also has a key role in the production and excretion of bile. In fetal life, haematopoiesis is one of the key functions which is performed by liver.
Liver resectioning is a technique employed for correction of numerous ailments or for the purpose of experimental study. Diseases such as tumorous growths on the liver, hepatic necrosis, cyst formation, hepatic abscess, hepatic lobe torsion and numerous others require the removal of the affected part of the liver(Martin et al. 2003; Pignon et al. 2013). The remaining liver usually recovers by regeneration through hyperplasia and hypertrophy of healthy cells of the un-affected part of the liver (Palmes and Spiegel, 2004). For experimental reasons, where different aspects of liver regeneration process are to be studied, liver resectioning technique is employed (Mao et al. 2014; Fausto et al. 2012).
Numerous studies have been done to see the regeneration rate of liver in different species. In rats it has been noticed that liver can regenerate to its original size after two-third hepatectomy in only five to seven days (Mao et al. 2014).Another author states the recovery to occur in less than two weeks in rodents (Gilgenkrantz and Hortet, 2011). In humans it has been shown that resectioning up to 50 percent has resulted in complete regeneration of liver mass in only a period of two weeks (Häussinger, 2011).
Rabbits being small laboratory animals with comparative ease of handling have been used extensively for research purposes. Regeneration has been studied in rabbits post chemical insult on liver or through portal branch ligations (Palmes and Spiegel, 2004).
As opposed to general perception, Carpenter (2003) states that the rabbits fall under the category of rodents, they in actuality are lagomorphs. Two families composed of twelve genera and eighty-one species fall under the umbrella of order lagomorpha. They are cosmopolitan in their distribution. The main difference between rodents and lagomorphs is the presence of two pairs of upper incisors in the former group, whereas the later have only one pair of upper incisors. Despite having a great degree of similarity which these two groups share together, they are not thought to be closely associated. The animals of both the categories evolved into nine creatures separately and their similar dental patterns resulted from parallel evolution. All legomorphs consume foliage and practice caprophagy.
All lagomorphs are blessed with acute tactile and olfactory senses with a considerable long-haired fluffy body coat. Lagomorphs have big side-to-side set eyes giving them a broader circular vision. Testes are in the scrotum in front of the penis. Baculum is absent in males. Females bear two to five pairs of mammary glands.
Deficiency has been observed in terms of study of liver regeneration when liver resectioning is performed. The present study aims to focus on this aspect of research on soft tissue, which would enhance our understanding of liver regeneration and its rate in this specie.