Right and left lobes of prostate

The lower larger portion of the posterior surface of the prostate sometimes presents a shallow median furrow, which imperfectly separates it into a right and a left lateral lobe: these form the main mass of the gland and are directly continuous with each other behind the urethra.

According to the Terminologia Anatomica 2, the definitions of these divisions of the prostate [Lobi dexter, sinister et medius] are subject to much controversy and are not listed in the new TA2.

In the Terminologia Anatomica 1 (1998), for each lateral lobe of the prostate, four lobules were defined by the arrangement of ducts and connective tissue and may be distinguished with the unaided eye. But the combined inferoposterior/inferolateral lobules, the superomedial lobules and the anteromedial lobules correspond to the histological entities of McNeal [1988 Am J Surg Pathol 12: 619-633], and widely called after his usage, peripheral, central and transitional zones respectively.

• Combined inferoposterior/inferolateral lobules = Peripheral zone (PZ)
• Superomedial lobules = Central zone (CZ)
• Anteromedial lobules = Transitional zone (TZ)
• The middle lobe of prostate is now considered as a variation consisting of an independent prominence extending from the isthmus.

Sources: https://fipat.library.dal.ca/ta2/