What does SI mean? Definitions for SI Here are all the possible meanings and translations of the word SI.
The sebaceous glands are microscopic exocrine glands in the skin that secrete an oily or waxy matter, called sebum, to lubricate and waterproof the skin and hair of mammals.ebaceous glands secrete the oily, waxy substance called sebum (Latin: fat, tallow) that is made of triglycerides, wax esters, squalene, and metabolites of fat-producing cells. Sebum waterproofs and lubricates the skin and hair of mammals.
Sweat glands are small tube-like structures of the skin that  produce sweat, a fluid that is secreted by the body to maintain  thermoregulating balance. There are two main tâ¦ypes of sweat glands:  eccrine sweat glands and apocrine sweat glands.