Are sebaceous glands and hair arrector pili epidermis in the same grouping?

Sebaceous glands and hair arrector pili are not in the same grouping within the epidermis. Sebaceous glands are skin appendages found in the dermis, while hair arrector pili are smooth muscles located within the hair follicle.

The epidermis, the outermost layer of the skin, consists of keratinocytes and specialized cells such as melanocytes, Langerhans cells, and Merkel cells. Sebaceous glands are exocrine glands that secrete an oily substance called sebum to help keep the skin and hair moisturized. They are connected to hair follicles and open onto the skin surface through a pore.

On the other hand, hair arrector pili are small, involuntary muscles that attach to the hair follicle. When these muscles contract, they cause the hair to stand up, a response known as piloerection or goosebumps. Hair arrector pili muscles are located in the dermis, the layer of skin beneath the epidermis.

Sebaceous glands and hair arrector pili play distinct roles in skin and hair physiology, and while they are closely associated with hair follicles, they belong to different tissue layers and have different functions.