DR:
Most likely they are sebaceous, or oil glands. This is known as Fordyce's condition, after the dermatologist who noted it.
It's not a disease--just that oil glands, which we all have all over the face, are visib;e when there are enough of them on a pink background such as the lip. Cause: unknown. Treatment: unavailbale. Significance: nil.
Best.
Dr. R