Lecture_15_Comparative Anatomy_The Urogenital System

Each glomerulus is associated with a renal capsule

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Unformatted text preview: ng of the excretory duct.  The renal artery, a major branch from the dorsal aorta, delivers blood to the kidneys. This artery branches numerous times (the number is species dependent) before eventually forming tiny capillary beds known as glomeruli. Each glomerulus is associated with a renal capsule (Bowman’s capsule)  constituting the first portion of the nephron. Collectively, the glomerulus and renal capsule form the renal corpuscle. In short, an ultrafiltrate without blood cells and proteins is forced through the capillary walls and collects in the renal capsule before it passes through the proximal convoluted, intermediate, and distal convoluted tubules of the nephron before entering the collecting tubule. Different substances (e.g. sodium, glucose, etc.) are reabsorbed (into specialized arteries) at different points along the filtrates path through the nephron (see General Physiology). o Embryonic Development  Nephrotome to Nephric Tubules • The kidneys form within the intermediate mesoderm located in the dorsal and posterior body wall of the embryo. o At the onset of its differentiation, the afore mentioned posterior region of the intermediate mesoderm expands, forming a nephric ridge that protrudes slightly from the dorsal wall of the body cavity. o The next structure to appear is the paired nephrotome, the embryonic forerunner of the uriniferous tubule.  The nephrotome is often segmental and contains the nephrocoel, a coelomic chamber that may open via a ciliated peritoneal funnel to the coelom. • The medial wall of the nephrotome widens into a thin ­walled renal capsule into which grows the glomerulus. • The lateral end of the nephrotome grows outward and fuses with similar outgrowths to form successive nephrotomes to form the common nephric duct. At this point, the modified nephrotome can be described as a uriniferous tubule even though it may remain connected with th...
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This note was uploaded on 01/16/2012 for the course BI 200 taught by Professor Potter during the Fall '11 term at Montgomery College.

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