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Male reproductive organs

Last updated: December 16, 2020

Summary

The male reproductive system consists of the penis, testes, epididymis, ejaculatory ducts, prostate, and accessory glands. These organs function together to produce sperm and deliver semen from the testes via ejaculation. For more information on the embryological development of the male reproductive system, see “Development of the reproductive system”.

Penis

Function

Urination and release of semen

Gross anatomy [1][2]

Primarily composed of erectile tissue, blood vessels, nerves, and connective tissue

Structure

Arteries [1][2]

Arterial supply to the penis
Artery Course Supplies
Internal pudendal artery
  • External genitalia

Bulbourethral artery

Deep artery of the penis
  • Erectile tissue
Dorsal artery of the penis
Urethral artery
External pudendal artery

Veins

Venous drainage of the penis
Vein Anatomy Drains into
Deep dorsal vein of the penis
Superficial dorsal vein of the penis
  • External pudendal veins greater saphenous vein

Lymphatics

Innervation

Innervation of the penis
Innervation Structures Function
Parasympathetic
Sympathetic
  • Hypogastric nerve (T11–L4)
  • Emission
Sensory

Microscopic anatomy [1][2]

Embryology [1]

Testes, scrotum, and spermatic cord

Gross anatomy

Structure [1][2][3]

TIE turns into ICE”:
Transversalis fascia Internal spermatic fascia
Internal oblique → Cremasteric muscle and fascia
External oblique → External spermatic fascia

Vasculature, lymphatics, and innervation of the testes and scrotum [3]

Vasculature, lymphatics, and innervation of the testes and scrotum
Testes Scrotum
Arteries
Veins
  • Scrotal veins drain to external pudendal vein

Lymphatics

Autonomic Innervation

Motor innervation
  • None
Sensory innervation

The Left Gonadal vein is the LonGest.

Microscopic anatomy

Microscopic anatomy [1][2]

Spermatogonia

  • Description: undifferentiated germ cells lining the seminiferous tubules
    • Type A (dark): do not undergo mitosis
    • Type A (pale): form type B spermatogonia
    • Type B: undergo mitosis mature into primary spermatocytes
  • Function: differentiate into primary spermatocytes

Sertoli cells

The S-rule for Sertoli cells: line the Seminiferous tubes, Sustain Sperm Synthesis, and Suppress FSH.

Leydig cells

Leydis Love Testosterone”: Leydig cells are LH-stimulated and secrete Testosterone.

Sperm

Blood-testis barrier

Sertoli fence for sperm defense”: Sertoli cells form the blood-testes barrier.

Spermatogenesis and spermiogenesis

Spermatogenesis and spermiogenesis [1][2]

Spermatogenesis

Spermiogenesis

GONIUM is GOING to be sperm: Spermatogonia becomes a spermatid.
ZOON ZOOMS to the egg: Mature spermatozoon travel to the egg.

Embryology

Epididymis, ductus deferens, and accessory glands

Epididymis [1]

Ductus deferens [1]

Ejaculatory ducts [1]

Accessory glands [2]

Prostate (see below)

Seminal vesicles

Bulbourethral gland (Cowper gland)

Prostate gland

An accessory gland of reproduction located at the base of the bladder and composed primarily of glandular, fibrous, and smooth muscle tissue.

Function [2]

Secretion of:

Gross anatomy [1][2]

Structure

Vasculature, lymphatics, and innervation of the prostate gland [5]

Vasculature, lymphatics, and innervation of the prostate gland
Arteries
Veins

Lymphatics

Sympathetic innervation
Parasympathetic innervation

Microscopic anatomy [7]

General

Functional zones

Glands

  • There are ∼ 30–50 branched tubuloalveolar glands
  • Main prostatic glands are located peripherally
  • Periurethral submucosal glands

Embryology [8]

Male sexual response

There are three parts of the male sexual response: erection, emission, and expulsion.

Erection [2][9]

PDE-5 inhibitors (e.g., sildenafil) inhibit hydrolysis of cGMP ↑ NO → vasodilation prolonged erection

S2, S3, and S4 keep the penis off the floor.

Ejaculation [2][9][11]

Emission

Expulsion

Remember the ejaculatory pathway of sperm with SEVEn UP: Seminiferous tubules → Epididymis → Vas (ductus) deferens → Ejaculatory duct → Urethra → Penis

Innervation of male sexual response: Point, Squeeze, and Shoot.
1. Parasympathetic → Point (erection)
2. Sympathetic → Squeeze (emission)
3. Somatic (pudendal nerve) → Shoot (expulsion)

Clinical significance

Penis

Testes and scrotum

Prostate

Other

References

  1. Chung KW, Chung HM. Gross Anatomy. Lippincott Williams & Wilkins ; 2012
  2. Drake RL, Vogl W, Mitchell AWM. Gray's Anatomy for Students. Churchill Livingstone ; 2005
  3. Aaron L, Franco OE, Hayward SW. Review of Prostate Anatomy and Embryology and the Etiology of Benign Prostatic Hyperplasia. Urol Clin North Am. 2016; 43 (3): p.279-288. doi: 10.1016/j.ucl.2016.04.012 . | Open in Read by QxMD
  4. Swanson GP, Hubbard JK. A better understanding of lymphatic drainage of the prostate with modern imaging and surgical techniques.. Clin Genitourin Cancer. 2013; 11 (4): p.431-40. doi: 10.1016/j.clgc.2013.04.031 . | Open in Read by QxMD
  5. Bhavsar A, Verma S. Anatomic Imaging of the Prostate. BioMed Research International. 2014; 2014 : p.1-9. doi: 10.1155/2014/728539 . | Open in Read by QxMD
  6. Gartner LP, Hiatt JL. Cell Biology and Histology. Lww ; 2014
  7. Moore KL, Dalley AF, Agur AMR. Clinically Oriented Anatomy. Lippincott Williams & Wilkins ; 2013
  8. Stocco C. Tissue physiology and pathology of aromatase.. Steroids. 2012; 77 (1-2): p.27-35. doi: 10.1016/j.steroids.2011.10.013 . | Open in Read by QxMD
  9. Dean RC, Lue TF. Physiology of Penile Erection and Pathophysiology of Erectile Dysfunction. Urol Clin North Am. 2006; 32 (4): p.379-395. doi: 10.1016/j.ucl.2005.08.007 . | Open in Read by QxMD
  10. Jonas Boström, Anders Hogner, and Stefan Schmitt. Do Structurally Similar Ligands Bind in a Similar Fashion?. Journal of Medicinal Chemistry. 2006 .
  11. Alwaal A, Breyer BN, Lue TF. Normal male sexual function: emphasis on orgasm and ejaculation.. Fertil Steril. 2015; 104 (5): p.1051-60. doi: 10.1016/j.fertnstert.2015.08.033 . | Open in Read by QxMD