Mammary Gland

Mammary Gland

1. Embryology

   • Origin
     • The breasts develop from the mammary ridge or milk line, an ectodermal band.
   • Fetal development:
     • Week 6: the mammary ridge forms
     • Month 5: The primary epithelial buds develop, which will form the main lactiferous ducts.
     • Month 5: The primary epithelial buds develop, which will form the main lactiferous ducts.
   • Postnatal development
     • Puberty: Hormones (estrogen and progesterone) stimulate the growth of glandular tissue and stroma, forming the adult breasts.

2. Breast Anatomy

   • Location
     • They are located over the pectoralis major and minor muscles, extending from the second to the sixth rib.
   • External structure
     • nipple: central projection with the opening of the lactiferous ducts
     • Areola: The pigmented area of ​​skin surrounding the nipple. .
   • Internal structure
     • Parenchyma (Glandular tissue)
       • Lobes: Between 15 and 20 lobes per breast, each with a network of ducts. (Glandular tissue)
       • Lobules. Functional units that contain the acini or alveoli, where milk is produced.
   • Stroma (Supporting tissue)
     • Adipose tissue: Fills the spaces between the lobes, giving shape and size to the breast
     • Fibrous connective tissue: Supports the glandular tissue and forms the Cooper's ligaments, which provide support to the breast.
   • Lymphatic Drainage: It is crucial for the metastasis of breast cancer. Most lymphatic vessels drain towards the axillary lymph nodes

3. Breast histology

   • Glandular tissue
     • Glandular Epithelium: Cells that line the acini and ducts. These are the cells that produce milk.
     • Myoepithelial cells: Surround the acini and contract to expel milk into the ducts
   • Histological Changes: Breast histology varies with age, the menstrual cycle, pregnancy, lactation, and menopause.
   • Connective Tissue
     • Olagen and fibroblast: They form the dense stroma that supports the lobules and ducts.
     • Adipocytes: Fat cells that make up most of the volume of the non-lactating breast