Mammary glands are modification of
Sebaceous glands
Sebaceous glands are tiny, microscopic structures present in the skin. They produce sebum to lubricate the skin and hairs.
Sweat glands
Sweat glands are glandular tubular structures present in the skin. They produce sweat to maintain the body temperature. Sweat contains salts, urea, ammonia and water.
Mammary glands
Mammary glands are the modified sweat glands that contain glandular tissue and variable amounts of fat. They are present in the chest region.
Meibomian glands
Meibomian glands are tiny glands present at the corners of the eyelids and secrete oil which prevents the tears from drying out.