Penis & scrotum

General

Anatomy & histology-male urethra


Editorial Board Member: Bonnie Choy, M.D.
Deputy Editor-in-Chief: Maria Tretiakova, M.D., Ph.D.
Jesus Adrian Chavez, M.D.
Debra L. Zynger, M.D.

Last author update: 20 July 2023
Last staff update: 20 July 2023

Copyright: 2002-2024, PathologyOutlines.com, Inc.

PubMed Search: Urethra anatomy normal male

Jesus Adrian Chavez, M.D.
Debra L. Zynger, M.D.
Page views in 2023: 7,421
Page views in 2024 to date: 3,417
Cite this page: Chavez JA, Zynger DL. Anatomy & histology-male urethra. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/prostateurethramalenormal.html. Accessed May 19th, 2024.
Definition / general
Essential features
  • Subepithelium composed of loose fibroelastic tissue, glands and abundant vessels
  • Muscle layers include smooth muscle and exterior skeletal muscle
  • Size, structure and function differ in men and women
Diagrams / tables

Images hosted on other servers:
Male urethra Male urethra

Male urethra

Male urethra

Male urethra

Prostatic urethra

Prostatic urethra

Male urethra development

Male urethra development

Clinical features
Gross description
Gross images

Contributed by Debra L. Zynger, M.D.
Prostatic urethra

Prostatic urethra

Penile urethra Penile urethra

Penile urethra

Microscopic (histologic) description
  • Urothelium
    • Basal layers are composed of either low columnar or cuboidal cells, followed by several layers of polyhedral cells
    • Most superficially composed of round, dome shaped umbrella cells that are occasionally multinucleated and flattened according to amount of distention
  • Stratified / pseudostratified columnar epithelium
    • Multiple cell layers of polyhedral cells; the most superficial are columnar
    • Stratified / pseudostratified; in the pseudostratified layer, all cells are in contact with the basal layer
  • Nonkeratinizing squamous epithelium
    • Composed of multiple layers
    • Divided into zones according to cell shapes: cuboidal (deepest), polymorphous (middle), squamous / flattened (superficial)
  • Urethral / periurethral glands
    • Bulbourethral (Cowper) glands: mucous - acinous glands in the bulbous and membranous urethra with uniform pale cytoplasm and basal, compressed nuclei
    • Littré glands: tubuloacinar mucinous glands with uniform, pale eosinophilic to clear cytoplasm and basally flattened nuclei in penile urethra (Mills: Histology for Pathologists, 4th Edition, 2012)
    • Intraepithelial (juxtaepithelial) glands: nests of cells with eosinophilic to flocculent cytoplasm with basally placed nucleus located at the junction of the epithelium and subepithelium
Microscopic (histologic) images

Contributed by Debra L. Zynger, M.D.
Prostate, cross section with prostatic urethra

Prostate, cross section with prostatic urethra

Prostatic urethra

Prostatic urethra

Prostatic verumontanum and prostatic urethra

Prostatic
verumontanum
and prostatic
urethra

Bulbourethral (Cowper) glands Bulbourethral (Cowper) glands

Bulbourethral (Cowper) glands


Penile urethra

Penile urethra

Penile intraepithelial (juxtaepithelial) glands

Penile intraepithelial (juxtaepithelial) glands

Penile glands of Littre

Penile glands of Littré

Fossa navicularis

Fossa navicularis

Differential diagnosis
  • Prostatic adenocarcinoma, foamy type:
    • Mimics bulbourethral (Cowper) glands
    • Usually admixed with classic prostatic adenocarcinoma
    • Not exclusively located near skeletal muscle / apex of the prostate
    • Completely lacks basal cells (negative for CK5/6, p63, etc.)
    • Has expression of AMACR
Board review style question #1

The image above shows a prostate needle core biopsy that also contained skeletal muscle (not shown). What is your diagnosis?

  1. Bulbourethral (Cowper) glands
  2. Fossa navicularis
  3. Prostatic adenocarcinoma, atrophic type
  4. Prostatic adenocarcinoma, foamy type
Board review style answer #1
A. Bulbourethral (Cowper) glands. Bulbourethral (Cowper) glands are shown, which are near the prostatic apex and usually in close proximity to skeletal muscle. These are a mixture of mucinous glands with bland flattened nuclei and occasional nonmucinous glands / ducts in which the multilayered nature of the epithelium is easier to appreciate. Bulbourethral (Cowper) glands mimic prostatic adenocarcinoma. In particular, the mucinous glands overlap in morphology with foamy prostatic adenocarcinoma. In difficult cases, immunostains can be performed in which adenocarcinoma will lack basal cells and have expression of AMACR, while bulbourethral (Cowper) glands will have patchy basal cells and have weak to no AMACR staining.

Answer B is incorrect because fossa navicularis is a part of the penile urethra, lined by squamous epithelium. Answer C is incorrect because prostatic adenocarcinoma, atrophic type is a type of carcinoma that mimics atrophy. Answer D is incorrect because prostatic adenocarcinoma, foamy type is a type of carcinoma that mimics bulbourethral glands. Prostatic adenocarcinoma, foamy type will not have the bland duct structures mixed with mucinous glands and will not be exclusively found near skeletal muscle.

Comment Here

Reference: Anatomy & histology-male urethra
Back to top
Image 01 Image 02