Simple cuboidal epithelium definition

A form of simple epithelium known as simple cuboidal epithelium is composed of cube-shaped cells with spherical, primarily centrally placed nuclei. They were developed largely to improve the operation of certain organs. Since the basic cuboidal epithelium only consists of a single layer of cells, every cube-shaped cell is connected directly to the basement membrane.

Structure of the simple cuboidal epithelium

• Due to its inability to form ducts, the cuboidal epithelium’s cells are not perfectly cubical. However, they are roughly as high as they are broad.
• The nucleus is more prominent and is positioned in the centre of the thicker cells.
• The cells are roughly cube-shaped and comparable in size to one another.
• Because of their larger thickness, mitochondria and other organelles may contain large amounts of cytoplasm, allowing for high levels of active transport across the epithelium as well as other tasks.
• Because the epithelium functions as a defensive coating or lining, the cells are densely bound together, with practically no intracellular space between them.
• The cuboidal epithelium, like all other types of epithelial tissues, consists of cube-shaped cells, has adhesions and junctions on the lateral side to help link neighbouring cells, and the apical surface of the cells is oriented toward the organ or duct lumen.
• Several cells in the simple cuboidal epithelium, like those lining the bronchioles and kidney tubules, have ciliated apical surfaces.
• The cilia are generally 0.2 m in diameter and 5 to 10 m long. Nine peripheral microtubule doublets are arranged in a circular pattern around two central microtubules to form the core structure of each cilium.
• The fast beating patterns of cilia cause a stream of liquid and suspended particles to flow along the epithelium in one direction.
• These cilia facilitate excretion as well as secretion by guiding the flow of molecules in a certain direction.
• The basic cuboidal epithelium lacks a direct blood supply to its cells.
• Despite being directly connected to the basement membrane, they obtain nutrients, water, and gases via diffusion from the surrounding tissue.
• The cells are nonetheless innervated and supplied with nerves.

Functions of the simple cuboidal epithelium

The simple cuboidal epithelium’s key tasks are secretion, absorption, and covering because of the form of the cells.

1. Covering/Protection

• They safeguard several organs from damage and other poisons by acting as a coating.
• The cuboidal epithelium in the ovaries generates the ovarian surface, which maintains the ovum’s activity in the ovary and restores and heals ovulation-related injury.
• Additionally, they line the testicular seminiferous tubules’ outside lining.
• In certain locations, such as the lining of the ducts of the respiratory system, the cuboidal epithelium functions as a lining and protects the internal structure from mechanical wear and tear.

2. Secretion

In addition, they produce hormones and other physiologically active fluids like cerebrospinal fluid.

An illustration of this is the cuboidal epithelium in the thyroid glands that lines the thyroid follicles where thyroid hormone is produced.

The cuboidal cells that make cerebrospinal fluid compose the only layer that makes up the ependyma in the brain.

3. Excretion

• They provide an excretion role as well, since the kidneys expel toxic by-products into the urine.
• Similar to this, the simple cuboidal epithelium that is responsible for producing sweat and oil products is likewise a derivation of the lining of the sweat and sebaceous glands.
• A significant quantity of mitochondria as well as other organelles facilitate the active transport mechanism necessary for the elimination of various pollutants.

4. Absorption

• Depending on their position, the cells of the simple cuboidal epithelium might engage in active or passive transport of materials.
• The simple cuboidal epithelium-lined proximal as well as distal convoluted tubules of the kidneys remove excess water as well as other waste products while maintaining the pH and ion balance of the body.
• The kidneys’ cuboidal epithelial cells have cilia on their apical surfaces that support the absorptive process.

Location and Examples of Simple cuboidal epithelium

• They are everywhere in the body and change depending on how the organs work.
• In addition to covering many organs and performing excretory and absorptive duties, they line the respiratory tract, the tubules of the kidney, as well as the smaller ducts of a number of glands.
• Similar to the last illustration, the thyroid follicle in the thyroid glands is a straightforward cuboidal epithelium.
• They encircle the epididymis, the surface of the ovary, and a portion of the testes.
• This epithelium similarly forms the pigmented epithelium on the posterior aspect of the retina of the eye, as well as the anterior side of the capsule of the lens of the eye.
• They also make up part of several glands that secrete, including the thyroid and the pancreas.

References and Sources

• Mescher AL (2016). Basic Histology. Fourteenth Edition. McGraw-Hill Education.
• Tortora GJ and Derrickson B (2017). Principles of Physiology and Anatomy. Fifteenth Edition. John Wiley & Sons, Inc.
• Waugh A and Grant A. (2004) Anatomy and Physiology. Ninth Edition. Churchill Livingstone.
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