Juxtaglomerular Apparatus:

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Juxtaglomerular Apparatus is located at the vascular  pole of renal corpuscle.

It consists of macula densa, extraglomerular mesangial cells and juxtaglomerular cells.

The extraglomerular mesangial cells also known as Polkissen cells or lacis cells or goormaghtigh cells.

Macula Densa :

                   Macula Densa is a patch of densely packed epithelial cells on the renal corpuscle side of the distal straight tubule (as it passes between the efferent and afferent arteriole). These cells are intimately associated with juxtaglomerular mesangial cells.

Juxtaglomerularmesangial cells :

these cells are found between the macula densa and the two arterioles and are continuous with the mesangial cells within the glomerulus.

Juxtaglomerular cells- are primarily present in the afferent arteriole of tunica media layer. These cells derived from smooth muscle.

Peripolar cells �has recently identified in the juxtaglomerular apparatus. These cells are located at the vascular pole of renal corpuscle. They are found between the parital and visceral layers of the glomerular capsule and the face the urinary space.

Ureter :

            Tunica Mucosa- is thrown in to longitudinal folds

            Epithelium- Lined by transitional epithelium.

            Lamina Propria- form of loose connective tissue. In case of horse, mucosal glands are present.

            Lamina Muscularis-  absent

            Tunica submucosa - blended with lamina apropria

            Tunica muscularis- Smooth muscle fibers (3 layers)

            Tunica adventitia-  typical

Urinary Bladder:

Tunica mucosa-

Epithelium- Transistional epithelium

Lamina Propria- loose connective tissue

Lamina muscularis- Small isolated smooth  muscle fiber bundles. (in cats,  this layer is absent), well developed in horse.

Tunica Submucosa- dense connective tissue

Tunica muscularis- the smooth muscle fibers are called detrusor muscle, which forms interweaving bundles.

Urethra:

Tunica mucosa- crescent shaped lumen

Epithelium- Initially-transitional epithelium nearing to the terminal stratified squamous type.

Lamina propria-submucosa- Loose connective tissue and numerous blood vessels.

Tunica muscularis- form of circularly and longitudinally arranged muscle fibers.