What type of epithelial cells are exocrine glands primarily composed of?

Exocrine glands are primarily composed of cuboidal epithelial cells. These cells are typically arranged in a single layer, allowing for efficient secretion of various substances, including enzymes, mucus, and sweat, directly into ducts or onto surfaces. The shape of cuboidal cells, which are roughly as wide as they are tall, is well-suited for their role in secretion, providing enough space for organelles involved in synthesis and secretion, such as the endoplasmic reticulum and Golgi apparatus.

In contrast to cuboidal cells, other types of epithelial cells serve different functions. Simple squamous cells, for example, are thin and flat, primarily involved in passive transport processes like diffusion and filtration. Pseudostratified columnar cells, while useful for secretion and movement (such as in the respiratory tract), are taller and often have cilia, which is not characteristic of exocrine gland structure. Squamous endothelial cells line blood vessels and are adapted for smooth surface and minimal resistance to blood flow, rather than secretion. Thus, the specific structure of cuboidal epithelial cells aligns perfectly with the needs of exocrine glands to perform their function effectively.