The breast would not contain muscles. Breast tissue is located on top of the muscles in the chest wall. Blood vessels and lymphatic vessels (a method of vessels that drains fluid) are located through the entire breast. Breast tissue commences to type in the fourth week of fetal daily life. https://grok.com/share/c2hhcmQtMw%3D%3D_21b4ddf4-c274-418a-a078-c9d2af4898ff