Veterinary Histology UFF
Department of Morphology - Biomedic Institute
LaBEc - Laboratory of Cellular and Extracellular Biomorphology
 
Veterinary Histology Atlas
    Versão em Português
Introduction
Urinary System

Functions
• Contributes to the maintenance of the homeostasis (regulatory function)
Balance of water and electrolytes

Constitution

Kidney
• Covered by a capsule of dense connective tissue
• The morphofunctional unit of the kidneys is the nephron
• Presents a cortical and medullar zone

 

Cortical
• Corpuscle of Malpighi
• Proximal and distal convoluted tubule
• Medullary arrays and vessels


 

Medullar
• Loop of Henle
• Collecting Tubules: Reunite forming larger and larger tubes that direct themselves towards the renal papilla
- Tubes with a smaller diameter have simple cuboidal epithelium
- Larger tubes have columnar cells

 

Néfron

I- Renal Corpuscle (or of Malpighi)
• Bowman’s Capsule
• Has two sheets:
- Parietal: Simple squamuous epithelium
- Visceral: Podocytes with projections over the membrane of the capillaries (Modified epithelium)

 

 

II- Malpighi’s Glomerulus
• Formed by fenestrated capillaries
• Derived from the afferent arteriole
• Coil themselves and reunite to form the efferent arteriole
• We find:
- Over the membrane of the capillaries, the podocytes
-
Between the basal membrane and the capillaries, the mesangial cells

 

 

 

III- Proximal Convoluted Tubule
• Walls formed by simple cuboidal epithelium
• Cells with acidophilic cytoplasm
• In the apical portion, they possess numerous microvilli that form the brush border
In the basal portion it presents cytoplasmic expansions

 

 

IV- Loop of Henle
• Thin descending limb: Simple squamous epithelium
• Thick ascending limb:
Simple cuboidal epithelium

 

V- Distal convoluted tubule
• Last segment of the nephron
• Wall composed of simple cuboidal epithelium
• Small and scattered microvilli
• Pale acidophil cytoplasm
Does not present a brush border in its apical portion

Bladder
• A hollow organ, it’s a bag

Mucosa
• Transitional Epithelium: Their cells change shape according to the functional moment (pressure exerted by urine)
• The lamina propria is of loose to dense connective tissue.

Muscularis
• Smooth muscle laid out in three layers: Inner longitudinal, Middle circular e Outer longitudinal
• Close to the urethra the muscle forms the bladder’s internal sphincter

Adventitia or Serosa: In the upper portion of the bladder there is a serosa, the rest is adventitia


Ureter
• Present the same basic structures as the bladder, less thick
• Has a valve that prevents the reflux of urine
Urethra
• Tube that takes the urine from the bladder to the outside

Male Urethra
• Formed by three portions:

Prostatic
• Very close to the bladder
• Lined by transitional epithelium

Membranous
• Lined by a pseudostratified columnar epithelium
• Has the external sphincter of the urethra

Penile or Cavernous
• Located in the corpus cavernosum penis
• Lined by pseudostratified columnar epithelium, but with stratified squamous areas

Female Urethra
• Lined by stratified squamous epithelium with areas of pseudostrafied columnar
• Has the external sphincter of the urethra


Credits
Tissues
Epithelial
Connective
Cartilaginous
Osseous
Nervous
Muscle
Systems
Circulatory
Blood
Imune
Digestive
Accessory Gls.
Respiratory
Integumentary
Urinary
Endocrine
Male Reprod.
Female Reprod.
Birds Histology
Quiz
Videos
Bibliography