If white stuff can be squeezed out from inside the acne, it is whitehead acne, also known as closed acne. Patients who develop acne generally have a high secretion of sebaceous glands, such as is common during puberty. A high secretion of sebaceous glands can provide excellent conditions for the growth of microorganisms such as Propionibacterium acnes in the hair follicles, such as an oily, anaerobic environment. Propionibacterium acnes, on the other hand, can hydrolyze the triglycerides in sebum into free fatty acids, which in turn stimulates keratin at the ducts of the hair follicles, creating cell proliferation and hyperkeratosis. This can cause sebum excretion to be blocked and sebum and keratin plugs to accumulate at the mouth of the follicle, then acne can form and squeezing can appear as a white thing.