Prostate

Staci Bryson, MD

Key Facts

Embryology

Forms in early embryonic life from condensation of mesenchyme along pelvic urethra
- Mainly urogenital sinus mesenchyme
- Prostate base and central zone form from wolffian duct mesenchyme
Glandular epithelium forms from outgrowths of prostatic urethral endoderm
- Initially forms as at least 5 solid prostatic cords
- Epithelial buds begin to branch at 10 weeks
- Cords develop a lumen and glandular acini by 11 weeks
- Glands begin secretory activity by 13-15 weeks
Initial formation of prostatic cords is induced by mesenchyme
- Dependent on conversion of testosterone to dihydrotestosterone
Neural crest-derived neuroendocrine cells necessary to induce branching
Achieves adult contour and location by 9 weeks

Macroscopic Anatomy

Located within true pelvis between bladder neck and urogenital diaphragm
Funnel shaped with base at bladder neck and apex at urogenital diaphragm
Outer zones are termed peripheral and central
- Central is toward base
Inner zone (periurethral) is termed transitional
Prostatic urethra begins on superior surface and descends through prostate almost vertically
Term prostate measures ˜ 1 cm

Microscopic Anatomy

Combination of glandular and nonglandular tissue
Glandular tissue is composed of 3 main epithelial cell types: Basal cells, luminal cells, and neuroendocrine cells
Basal cells
- Proliferative compartment of glandular prostate
- Low cuboidal and columnar cells
- May have prominent nuclear grooves and prominent nucleoli
Apical/luminal cells
- Columnar cells with overall basally oriented round nuclei
- Luminal cells normally have some variation in size and shape (anisopoikilocytosis)
- Abundant cytoplasm with numerous small secretory vacuoles
- Secretory vacuoles are most dense in peripheral and transitional zones and give pale to clear appearance to cytoplasm
- Cytoplasm with fewer secretory granules in central zone gives a slightly darker appearance to cytoplasm
Neuroendocrine cells: Scattered cells in basal cell layer, not readily apparent by light microscopy, rich in serotonin, neuron-specific enolase, and peptide hormones
4th epithelial cell type termed “transitional cells” have an immunophenotype with overlap between that of basal and luminal cells
Nonglandular tissue includes anterior fibromuscular stroma and prostatic capsule
- Anterior fibromuscular stroma consists of coarse interwoven muscle fibers, best developed at apex of prostate
- Prostatic capsule consists of inner smooth muscle layer and outer collagenous membrane; relative thickness and relationship between components varies within prostate