Histological Structure
The PCT is lined with a single layer of
cuboidal epithelial cells that have a distinctive brush border of microvilli on their apical surface. These microvilli increase the surface area for reabsorption. The cells contain numerous
mitochondria, providing the energy required for active transport processes.
Function of the PCT
The primary function of the PCT is to reabsorb approximately 65% of the glomerular filtrate, which includes water, sodium, chloride, potassium, calcium, and bicarbonate ions. It also absorbs almost all the glucose, amino acids, and other nutrients. The PCT actively transports sodium ions out of the filtrate and into the peritubular capillaries, followed by water and other solutes.Histochemical Staining
Histological examination of the PCT often employs special staining techniques.
Periodic Acid-Schiff (PAS) stain is commonly used to highlight the brush border and basement membrane. Hematoxylin and Eosin (H&E) staining is also used to differentiate the cellular components.
Pathological Considerations
Damage to the PCT can result in impaired reabsorption, leading to conditions such as
Fanconi Syndrome. In this condition, the PCT fails to reabsorb crucial substances, resulting in their loss in urine. Additionally, the PCT can be affected by toxins, ischemia, and inflammatory conditions, which can disrupt its function.
Clinical Relevance
The PCT is a target for several diuretics, which inhibit sodium reabsorption and increase urine output. Understanding the histology and function of the PCT is essential for comprehending the mechanisms of action of these medications and their therapeutic implications.Conclusion
The Proximal Convoluted Tubule is an essential component of the nephron, with a complex histological structure that facilitates its primary role in reabsorption. Its health and function are crucial for maintaining the body's fluid and electrolyte balance.
