= Renal corpuscle
A <renal corpuscle> is the initial filtration structure of a <nephron>, consisting of a <glomerulus> enclosed by a <glomerular capsule>, also called <Bowman's capsule>. <Blood> flows through the glomerular <capillaries>, while filtered fluid enters the surrounding capsular space and then the <proximal tubule>. The blood pathway and the tubular-fluid pathway are adjacent but distinct.<Kidneys by the National Cancer Institute>[nephron organization: glomerulus and surrounding epithelial capsule]{ref}
The <glomerular filtration barrier> includes capillary <endothelium>, a <basement membrane> and the specialized surface formed by <podocytes>. These biological cells extend processes around the capillaries. In a 1999 study, antibody-based localization placed the <membrane protein> <nephrin> at the slit diaphragm between podocyte processes, connecting a named molecular component to the physical filtration interface.<Nephrin is specifically located at the slit diaphragm of glomerular podocytes by V. Ruotsalainen and others>[Abstract and immunolocalization results]{ref}
A section supplies a useful scale comparison: the rounded structure containing a capillary tuft and its surrounding capsule is the <renal corpuscle>, whereas the <glomerulus> is the tuft inside it. Counting those as separate complete filtration units would double-count parts of the same unit. Filtered <water> and small <solutes> still undergo later processing, so the fluid first leaving a corpuscle is not identical to final <urine>.
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