Final answer:
The breast, primarily made up of adipose tissue, lies superficially to the pectoralis major muscle and serves the reproductive function of lactation.
Step-by-step explanation:
The breast is a mound of adipose tissue located superficial to the pectoralis major muscle. Comprising both adipose and glandular tissues, the breast is considered an accessory organ of the female reproductive system with the primary function of lactation, or milk production, to nourish an infant. Each breast contains lobules where milk is produced; this milk then passes through lactiferous ducts and sinuses to reach the nipple. Aside from its role in lactation, the size and shape of the breast are determined by the amount of adipose tissue present, which varies among individuals without affecting the capability of milk production.