Pathology > Study Images > Male Genitals > Prostate > Anatomy & Histology
Objectives Anat & Hist Benign Neoplasms

I. Gross Anatomy and Histology

Objectives:

After completing this section you will be able to:

  • list the various parts and structures that form the prostate
  • describe the basic gross anatomy and histology of the prostate
  • explain the clinical importance of the various areas within the prostate

  1. Anatomy

The prostate is a fibromuscular and glandular organ shaped like an inverted cone with its base in contact with the urinary bladder neck and the apex in contact with the superior fascia of the urogenital diaphragm. The organ completely surrounds the prostatic urethra. A fibrous capsule surrounds it. Enclosing the capsule is a dense fascial sheath, the prostatic sheath, which is part of the pelvic fascia. The fascial sheath contains the prostatic venous plexus, lymphatics and nerves. Behind the urethra, the two ejaculatory ducts traverse the prostate obliquely and antero-medially from its postero-superior margin to enter the prostatic urethra on either side of the prostatic utricle.

Question: What is the prostatic utricle?

Although no definite lobes are evident either externally or internally, the prostate is divided into several lobes:

The anterior lobe: This is used to describe the anterior portion of the organ lying in front of the urethra. It is devoid of glandular tissue being formed completely of fibromuscular tissue.

The median lobe: A cone-shaped portion of the organ situated between the two ejaculatory ducts and the urethra.

The lateral lobes: The right and left lateral lobes form the main mass of the organ and are continuous posteriorly. They are separated by the prostatic urethra.

The posterior lobe: This is used by some to describe the postero-medial part of the lateral lobes that can be palpated through the rectum.

  1. Histology

The prostate contains glands that open into the prostatic urethra. The glands are embedded in a stroma composed of smooth muscle fibers and fibrous connective tissue. Incomplete septa extend from the fibrocollagenous prostatic capsule into the organ to divide it into about 50 ill-defined lobules. The organ contains three separate groups of compound tubulo-alveolar glands arranged concentrically around the urethra:

Mucosal (inner periurethral) glands: These open directly into the urethra over its entire surface. The layer is the smallest of the three.

Submucosal (outer periurethral) glands: Glands from this layer, which is larger than the mucosal glandular layer, drain through short ducts into the urethra sinuses.

Main prostatic glands: This layer constitutes the bulk of the organ occupying two-thirds of the gland. The glands drain into the urethra via long ducts.

The mucosal and submucosal layers form the central glandular zone while the main prostatic glands form the peripheral glandular zone.

Question: What is the clinical importance of the dividing the prostatic glandular layers into zones?

An inner layer of tall columnar cells and an outer layer of cuboidal cells line prostatic glands. The lumen may contain ovoid or spherical, eosinophilic, lamellated bodies called corpora amylacea (starchy bodies) or prostatic concretions. These may calcify and form prostatic calculi, which when large may mimic carcinoma by producing the hard irregular consistency of carcinoma on digital rectal examination. In some cases the calculi are relatively mobile and give the palpating finger the impression of a beanbag.


Low magnification view of the prostate showing glandular units surrounded by stroma rich in smooth muscle.


Portion of prostate showing glands and surrounding fibromuscular stroma. Two corpora amylacea are present.


Higher magnification of prostatic glands showing the two-layer epithelium and a good example of a corpus amylaceum.

Objectives Anat & Hist Benign Neoplasms