What components make up the terminal ductal unit (TDLU)?

The terminal ductal unit (TDLU) is the fundamental functional and structural unit of the breast, consisting primarily of both the intralobular and extralobular terminal ducts. This unit is crucial for the understanding of breast anatomy, especially in contexts like mammography and pathology.

Intralobular terminal ducts are the smaller ducts that lead from the lobules, where milk is produced, to the larger ducts that convey milk to the nipple. On the other hand, extralobular terminal ducts connect the intralobular ducts to the larger ducts that eventually drain into the nipple. The presence of both types of ducts, along with the surrounding glandular tissue, makes the TDLU essential in the functional architecture of the breast.

This comprehensive structure allows for the efficient transport of milk during lactation and plays a significant role in the overall biological function of the breast, making the inclusion of both duct types fundamental to the definition of the terminal ductal unit. Understanding the anatomy and function of the TDLU is essential for health professionals who examine breast tissue for normal physiology and disease processes.