Name the sac-like gland found attached at the base of hair follicles.

The sac-like gland found attached at the base of hair follicles is the sebaceous gland. These glands are responsible for producing sebum, an oily substance that helps to lubricate and protect the skin and hair. Sebaceous glands are located in the dermis layer of the skin and are generally associated with hair follicles. The sebum they produce plays a crucial role in maintaining skin hydration and preventing the hair from becoming dry and brittle.

Understanding the function and location of sebaceous glands is fundamental in the study of skin and hair physiology, especially for those involved in manicuring and overall beauty treatments. Eccrine and apocrine glands, while also types of sebaceous glands, are related to sweat secretion and are not primarily associated with hair follicles. Follicular glands refer to a broader category and do not specifically denote the function or type of secretion associated with sebaceous glands. Thus, recognizing that the main function of sebaceous glands is to nourish and protect the hair through sebum production is key to identifying them correctly in this context.