D.sebaceous glands secrete oily substances onto the skin to maintain waterproof, impermeable barrier traits. skin can still function without these glands,The epidermis is not truly accessory as it is an essential part of the integument system. Without the epidermis the integumentary system cannot function ,accessory organs also occur in other systems eg the prostate in the reproductive system. Assessory organs aid in the performance of the system, but are not essential to the system function. thus epidermis is not accessory
