Cuboidal Epithelium with Brush Border of Microvilli
Biology · Structural Organisation in Animals · NEET
Simple cuboidal epithelium is a single layer of cube-shaped cells. In the proximal convoluted tubule (PCT) of the nephron, its free surface has many tiny finger-like folds called microvilli, and together they look like a "brush border". This brush border adds surface area for fast reabsorption of water and useful materials from the filtrate. Memory hook: "Cube cells + brush = PCT of the kidney".
Simple cuboidal epithelium: one layer of cube-shaped cells with central nuclei on a basement membrane; the free surface carries microvilli forming a brush border, as in the PCT of the nephron.
Your doubts, answered
Where exactly is cuboidal epithelium with a brush border of microvilli found?
It is found in the proximal convoluted tubule (PCT) of the nephron in the kidney. This is the most tested location in NEET. The brush border here helps the PCT reabsorb glucose, ions and water back into the blood. Plain (without brush border) cuboidal epithelium also lines ducts of glands and other kidney tubules.
What is the difference between microvilli and cilia? I keep mixing them up.
Microvilli are very small, non-motile (they do not move) finger-like folds of the cell surface. Many microvilli together form the brush border, and their job is to increase surface area for absorption. Cilia are longer, motile (they move) hair-like structures that beat to push mucus or particles along a surface, like in bronchioles. So: brush border = microvilli (absorb); moving hairs = cilia (transport).
Why does the PCT need a brush border?
The PCT does the largest amount of reabsorption in the nephron. A brush border of microvilli greatly increases the free surface area of each cell, so more water, glucose and ions can be taken back into the blood in less time. More surface area means faster and more complete reabsorption.
Is the brush border made of cilia or microvilli?
The brush border is made of microvilli, not cilia. This is a very common NEET trap. Remember that cilia are motile and move mucus, while a brush border is a still, dense carpet of microvilli used only for absorption.
Does ordinary cuboidal epithelium always have a brush border?
No. Simple cuboidal epithelium lines many places (ducts of salivary and other glands, and kidney tubules) but only shows a distinct brush border where strong absorption is needed, mainly the PCT of the nephron. So the brush border is a special feature, not present in every cuboidal lining.
⚠️ The NEET trap ✗ Cuboidal epithelium with a brush border is found in the lining of the intestine or in the ducts of salivary glands. ✓ The brush border of microvilli on cuboidal epithelium is characteristic of the proximal convoluted tubule (PCT) of the nephron. The intestine lining is columnar epithelium, and gland ducts have plain cuboidal epithelium. 🧠 Brush border on CUBE cells = PCT of kidney. Brush border on TALL cells = intestine (columnar). Do not swap them.
Real NEET questions
NEET 2020
Cuboidal epithelium with brush border of microvilli is found in:
A · Proximal convoluted tubule of nephron ✓
B · Eustachian tube
C · Lining of intestine
D · Ducts of salivary glands
Solution: Cuboidal epithelium is made of cube-like cells and lines gland ducts and kidney tubules. Where strong active reabsorption happens, it carries a brush border of microvilli to increase surface area. This brush-bordered cuboidal epithelium is characteristic of the proximal convoluted tubule (PCT) of the nephron. The Eustachian tube and salivary duct have other/plain epithelia, and the intestine has columnar epithelium, so (A) is correct.
Solved Structural Organisation in Animals NEET PYQs
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