Prostate - structure, topographic relations, prostatic urethra, ejaculatory ducts

Prostate - Structure, Topographic Relations, Prostatic Urethra, and Ejaculatory Ducts

Introduction-

The prostate is a walnut-shaped exocrine gland of the male reproductive system, essential for producing seminal fluid components. It is located in the pelvic cavity and surrounds the prostatic urethra.

Structure

Macroscopic Features:

1. Size and Shape:
   • Roughly 3 cm long, 4 cm wide, and 2 cm thick.
   • Weight: Approximately 20-30 grams in a healthy adult.
2. Zones (Anatomical):
   • Peripheral Zone:
     • Largest (70% of prostate volume).
     • Site of most prostate cancers.
   • Central Zone:
     • Surrounds the ejaculatory ducts.
     • Resistant to inflammation and carcinoma.
   • Transitional Zone:
     • Surrounds the prostatic urethra.
     • Most common site of benign prostatic hyperplasia (BPH).
   • Anterior Fibromuscular Stroma:
     • Contains no glandular tissue.
3. Capsule:
   • Dense fibromuscular tissue enclosing the gland.
   • Contains blood vessels and nerves.

Microscopic Features:

1. Glandular Tissue:
   • Tubuloalveolar glands producing seminal fluid.
   • Epithelium: Pseudostratified columnar and cuboidal cells.
2. Fibromuscular Stroma:
   • Smooth muscle interspersed with collagen.
   • Contracts during ejaculation to expel prostatic secretions.

Topographic Relations

1. Anterior:
   • Pubic symphysis (separated by the retropubic space of Retzius).
2. Posterior:
   • Rectum (separated by Denonvilliers’ fascia).
3. Superior:
   • Bladder neck and internal urethral sphincter.
4. Inferior:
   • Urogenital diaphragm and external urethral sphincter.
5. Lateral:
   • Levator ani muscles (pelvic diaphragm).

Prostatic Urethra

Features:

1. Length: Approximately 3 cm.
2. Lumen: Widest and most dilatable part of the urethra.
3. Structures:
   • Urethral Crest: Longitudinal ridge on the posterior wall.
   • Prostatic Sinuses: Depressions on either side of the crest, receiving openings of prostatic ducts.
   • Seminal Colliculus (Verumontanum):
     • Elevated area on the crest.
     • Contains the opening of the prostatic utricle and ejaculatory ducts.
   • Prostatic Utricle: Vestigial remnant of the paramesonephric duct.

Ejaculatory Ducts

1. Formation:
   • Union of the vas deferens and seminal vesicles.
   • Each duct is about 2.5 cm long.
2. Course:
   • Traverse the central zone of the prostate.
   • Open onto the seminal colliculus within the prostatic urethra.
3. Function:
   • Deliver sperm and seminal vesicle secretions into the urethra.

prostate diagram

Sources

1. Gray’s Anatomy for Students, 4th Edition.
2. Sobotta Atlas of Human Anatomy, 16th Edition.