Urine filtration in rats and mice because of the greater "orifice" size of the glomerulus through the filtration
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Bowman's capsule: high cuboidal epithelium, metaplasia, hyperplasia, adenomatoid transformation
The parietal layer of Bowman's capsule is usually lined by a layer of simple squamous epithelium but high cuboidal epithelium similar to that found in the proximal tubule may be seen in humans, monkeys, mice and rats.
In the mature male mouse this cuboidal epithelium is commonly seen and its prevalence is influenced by age and circulating levels of testosterone.182 Rats also seem to show this type of Bowman's capsule, males generally with a higher incidence or greater prominence than females.183,184 It is also more prevalent in spontaneously hypertensive strains than their normotensive counterparts and although its prevalence increases with advancing age it is not clear whether this predisposition is linked to hypertension.185 The parietal epithelium may show hypertrophy and hyperplasia in pathological conditions of the glomerulus, notably in advanced glomerulosclerosis of rats.89 It is also described in normal cynomolgus monkeys where the parietal cells form a continuum with those of the proximal tubule.186 There appears to be no sex-predominance in this species.
In humans, tubular type epithelium has been associated with malignant disease but it can also be found in normal subjects.187–190 It has been postulated that parietal epithelial cells have an important role in the development of focal segmental glomerulosclerosis and matrix production in humans.22,191
This change should be distinguished from herniation of proximal tubular epithelial cytoplasm into the capsular space that can occur as an artefact under certain conditions of fixation.192