diagnose renal disease in which the etiology is not clear based upon noninvasive means (clinical history, past medical history, medication history, physical exam, laboratory studies, imaging studies). in general, a renal pathologist will perform a detailed morphological evaluation and integrate the morphologic findings with the clinical history and laboratory data, ultimately arriving at a pathological diagnosis. a renal pathologist is a physician who has undergone general training in anatomic pathology and additional specially training in the interpretation of renal biopsy specimens. ideally, multiple core sections are obtained and evaluated for adequacy (presence of glomeruli) intraoperatively. a pathologist/pathology assistant divides the specimen(s) for submission for light microscopy, immunofluorescence microscopy and electron microscopy. the pathologist will examine the specimen using light microscopy with multiple staining techniques (hematoxylin and eosin/h&e, pas, trichrome, silver stain) on multiple level sections. multiple immunofluorescence stains are performed to evaluate for antibody, protein and complement deposition. finally, ultra-structural examination is performed with electron microscopy and may reveal the presence of electron-dense deposits or other characteristic abnormalities that may suggest an etiology for the patient's renal disease. other animals in the majority of vertebrates, the mesonephros persists into the adult, albeit usually fused with the more advanced metanephros; only in amniotes is the mesonephros restricted to the embryo. the kidneys of fish and amphibians are typically narrow, elongated organs, occupying a significant portion of the trunk. the collecting ducts from each cluster of nephrons usually drain into an archinephric duct, which is homologous with the vas deferens of amniotes. however, the situation is not always so simple; in cartilaginous fish and some amphibians, there is also a shorter duct, similar to the amniote ureter, which drains the posterior (metanephric) parts of the kidney, and joins with the archinephric duct at the bladder or cloaca. indeed, in many cartilaginous fish, the anterior portion of the kidney may degenerate or cease to function altogether in the adult. in the most primitive vertebrates, the hagfish and lampreys, the kidney is unusually simple: it consists of a row of nephrons, each emptying directly into the archinephric duct. invertebrates may possess excretory organs that are sometimes referred to as "kidneys", but, even in amphioxus, these are never homologous with the kidneys of vertebrates, and are more accurately referred to by other names, such as nephridia. in amphibians, kidneys and the urinary bladder harbour specialized parasites, monogeneans of the family polystomatidae. the kidneys of reptiles consist of a number of lobules arranged in a broadly linear pattern. each lobule contains a single branch of the ureter in its centre, into which the collecting ducts empty. reptiles have relatively few nephrons compared with other amniotes of a similar size, possibly because of their lower metabolic rate. birds have relatively large, elongated kidneys, each of which is divided into three or more distinct lobes. the lobes consists of several small, irregularly arranged, lobules, each centred on a branch of the ureter. birds have small glomeruli, but about twice as many nephrons as similarly sized mammals. the human kidney is fairly typical of that of mammals. distinctive features of the mammalian kidney, in comparison with that of other vertebrates, include the presence of the renal pelvis and renal pyramids and a clearly distinguishable cortex and medulla. the latter feature is due to the presence of elongated loops of henle; these are much shorter in birds, and not truly present in other vertebrates (although the nephron often has a short intermediate segment between the convoluted tubules). it is only in mammals that the kidney takes on its classical "kidney" shape, although there are some exceptions, such as the multilobed reniculate kidneys of pinnipeds and cetaceans. evolutionary adaptation kidneys of various animals show evidence of evolutionary adaptation and have long been studied in ecophysiology and comparative physiology. kidney morphology, often indexed as the relative medullary thickness, is associated with habitat aridity among species of mammals and diet (e.g., carnivores have only long loops of henle). society and culture egyptian in ancient egypt, the kidneys, like the heart, were left inside the mummified bodies, unlike other organs which were removed. comparing this to the biblical statements, and to drawings of human body with the heart and two kidneys portraying a set of scales for weighing justice, it seems that the egyptian beliefs had also connected the kidneys with judgement and perhaps with moral decisions. hebrew according to studies in modern and ancient hebrew, various body organs in humans and animals served also an emotional or logical role, today mostly attributed to the brain and the endocrine system. the kidney is mentioned in several biblical verses in conjunction with the heart, much as the bowels were understood to be the "seat" of emotion – grief, joy and pain. similarly, the talmud (berakhoth 61.a) states that one of the two kidneys counsels what is good, and the other evil. in the sacrifices offered at the biblical tabernacle and later on at the temple in jerusalem, the priests were instructed to remove the kidneys and the adrenal gland covering the kidneys of the sheep, goat and cattle offerings, and to burn them on the altar, as the holy part of the "offering for god" never to be eaten. india: ayurvedic system in ancient india, according to the ayurvedic medical systems, the kidneys were considered the beginning of the excursion channels system, the 'head' of the mutra srotas, receiving from all other systems, and therefore important in determining a person's health balance and temperament by the balance and mixture of the three 'dosha's – the three health elements: vatha (or vata) – air, pitta – bile, and kapha – mucus. the temperament and health of a person can then be seen in the resulting color of the urine. modern ayurveda practitioners, a practice which is characterized as pseudoscience, have attempted to revive these methods in medical procedures as part of ayurveda urine therapy. these procedures have been called "nonsensical" by skeptics. medieval christianity the latin term renes is related to the english word "reins", a synonym for the kidneys in shakespearean english (e.g. merry wives of windsor 3.5), which was also the time when the king james version of the bible was translated. kidneys were once popularly regarded as the seat of the conscience and reflection, and a number of verses in the bible (e.g. ps. 7:9, rev. 2:23) state that god searches out and inspects the kidneys, or "reins", of humans, together with the heart. food hökarpanna, swedish pork and kidney stew the kidneys, like other offal, can be cooked and eaten. kidneys are usually grilled or sautéed, but in more complex dishes they are stewed with a sauce that will improve their flavor. in many preparations, kidneys are combined with pieces of meat or liver, as in mixed grill. dishes include the british steak and kidney pie, the swedish hökarpanna (pork and kidney stew), the french rognons de veau sauce moutarde (veal kidneys in mustard sauce) and the spanish riñones al jerez (kidneys stewed in sherry sauce) . history kidney stones have been identified and recorded about as long as written historical records exist. the urinary tract including the ureters, as well as their function to drain urine from the kidneys, has been described by galen in the second century ad. the first to examine the ureter through an internal approach, called ureteroscopy, rather than surgery was hampton young in 1929. this was improved on by vf marshall who is the first published use of a flexible endoscope based on fiber optics, which occurred in 1964. the insertion of a drainage tube into the renal pelvis, bypassing the uterers and urinary tract, called nephrostomy, was first described in 1941. such an approach differed greatly from the open surgical approaches within the urinary system employed during the preceding two millennia. additional images right kidney kidney right kidney right kidney left kidney kidneys left kidney