How does the sebaceous gland synthesize sebum?

i know it contains things like triglycerides and cholesterol but i really would like to know how much is pulled from the blood stream and could the triglycerides be from ldl or vldl cholesterol?


or any relation ship with serum cholesterol at all?How does the sebaceous gland synthesize sebum?
The sebaceous glands are glands found in the skin of mammals.





Sebum


Sebaceous glands secrete an oily substance called sebum (Latin, meaning fat or tallow) that is made of fat (lipids) and the debris of dead fat-producing cells. In the glands, sebum is produced within specialized cells and is released as these cells burst; sebaceous glands are thus classified as holocrine glands.





Sebum is odorless, but its bacterial breakdown can produce odors. Sebum is the cause of some people experiencing ';oily'; hair if it is not washed for several days. Earwax is partly sebum.








Function


Sebum acts to protect and waterproof hair and skin, and keep them from becoming dry, brittle, and cracked. It can also inhibit the growth of microorganisms on skin.








Composition


The composition of sebum varies from species to species; in humans, the lipid content is as follows:





Percent composition Substance


25% wax monoesters


41% triglycerides


16% free fatty acids


12% squalene








Locations of glands


A branched type of acinar gland, these glands exist in humans throughout the skin except in the palms of the hands and soles of the feet.





Sebaceous glands can usually be found in hair-covered areas where they are connected to hair follicles to deposit sebum on the hairs, and bring it to the skin surface along the hair shaft. The structure consisting of hair, hair follicle and sebaceous gland is known as pilosebaceous unit.





Sebaceous glands are also found in non haired areas of lips, eyelids, penis, labia minora and nipples; here the sebum reaches the surface through ducts. At the rim of the eyelids, meibomian glands are a specialized form of sebaceous gland that secrete sebum into the tears coating the eye to prevent evaporation.





LDL and VLDL are apoprotein complex with lipids which play important roles in lipid metabolism. from intestinal cells to muscle or adipocyte for storage or liver for metabolisation to occur.





The fats contents of sebum is due to the sebaceous glands itself(its cell contents).