Testis and epididymis
Anatomy and histology

Author: Turki Al-Hussain, M.D. (see Authors page)

Revised: 8 December 2017, last major update August 2012

Copyright: (c) 2002-2017, PathologyOutlines.com, Inc.

PubMed Search: Testis and epididymis [title] Anatomy and histology

Cite this page: Anatomy and histology. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/testisanatomy.html. Accessed September 26th, 2018.
Definition / general
  • Birth to age 4 (static phase): seminiferous tubules filled with small cuboidal cells with no definite lumen present, Leydig cells usually not visible
  • Age 4-10 (growth phase): tubules, tubular lumina and cells enlarge; tubules become tortuous
  • Age 10 to puberty (maturation phase): tubular cells have mitoses; Leydig cells prominent; spermatocyte differentiation visible
  • Adult (postpuberty): each testis weights 15 - 19g, measures 5 × 3 cm; takes 70 days for cells to mature from spermatogonium to primary spermatocyte to secondary spermatocyte to spermatid to spermatozoa; maturation is orderly along length of tubule but often not present in biopsy cross section

  • Testes is paired organ suspended in scrotum by spermatic cord
  • Each testis is attached to an epididymis, which connects rete testis to vas deferens
  • Testis is composed of convoluted seminiferous tubules in a stroma with Leydig cells
  • Three layers: outer serosa (tunica vaginalis, extension of peritoneal cavity) with mesothelial cells; tunica albuginea (tough fibrous septa that extends into testis and separates it into 250 lobules of 1 - 4 seminiferous tubules), inner tunica vasculosa
  • Seminiferous tubules converge into rete testis at hilum, anastomose into efferent tubules that penetrate tunica albuginea to form head of epididymis
  • Efferent ducts: see micro images below
  • Epididymis: see epididymis
  • Interstitium: contains Leydig cells and stromal elements (collagen and myoid cells that surround seminiferous tubules)
  • Leydig cells:
    • Single (20 microns) or in clusters between seminiferous tubules, produce testosterone in response to luteinizing hormone (LH)
    • Often associated with nerve fibers and blood vessels
    • Have abundant pink cytoplasm with lipid, lipochrome pigment, Reinke crystalloids (hexagonal prisms by EM), round nuclei with distinct nucleoli
    • Fewer Leydig cells in elderly
  • Mediastinum: posterior testicular capsule with vasculature, nerves, mediastinum of rete testis (where tubules converge)
  • Rete testis:
    • At testicular hilum
    • Complex tubular architecture may resemble teratoma
    • Connects testicular tubules to 12 - 15 ciliated efferent ducts, which merge into a single duct, the epididymis at its head
    • Rete lined by flattened to columnar epithelium with numerous microvilli
    • Efferent duct lumina are narrower than epididymis, lined by ciliated columnar cells with microvilli
  • Seminiferous tubules:
    • 150 - 250 microns in diameter, the average total length in each testes is 540 m (range 299 - 981 m)
    • Lined by multilayered epithelium with most mature cells towards lumina
    • Have basal lamina, outer myoid cells (positive for desmin, muscle specific actin, vimentin) and collagen
    • Contain Sertoli cells, spermatogonia (types A and B), primary spermatocytes, secondary spermatocytes, spermatids and spermatozoa
    • All except spermatozoa are held together by a narrow cytoplasmic bridge
    • Immature tubules are positive for alpha inhibin
  • Sertoli cells:
    • Columnar, on basement membrane, surround germ cell elements with cytoplasmic extensions, form blood - testis barrier
    • 7% of tubular cells
    • May contain Charcot-Bottcher crystalloids (bundles of microfilaments)
    • Have irregular, highly folded nuclei with prominent nucleoli
    • Produce anti-Müllerian hormone, which causes regression of Müllerian duct structures in utero
    • After birth, secrete androgen binding protein and are responsive to FSH
    • Also produce inhibin
  • Vas deferens: see spermatic cord

Vestigial remnants:
  • Appendix epididymis: remnant of mesonephric duct
  • Appendix testis (hydatid of Morgagni):
    • Remnant of Müllerian duct; attached to tunica albuginea at upper testicular pole; present in 90% of males
    • May undergo hemorrhagic infarction from twisting on its pedicle
    • Gross: round / oval, 1 - 10 mm, pedunculated
    • Micro: columnar epithelium with vascular fibrous core with smooth muscle cells; may have glandular-like structures due to surface invaginations
  • Paradidymis (organ of Giraldes): remnant of mesonephric tubules
  • Vas aberrans (organ of Haller): remnant of mesonephric tubules
Diagrams / tables

Images hosted on other servers:


Transverse section

Right testis

Vertical section

Transverse section

Section of genital cord

Spermatic cord

Subcutaneous inguinal ring


Spermatic veins

Gross images

Images hosted on other servers:

Normal testis

Seminiferous tubules

Microscopic (histologic) images

Images hosted on PathOut server:

Contributed by Dr. Asmaa Gaber Abdou, Menofiya University, Egypt

Images hosted on other servers:

Appendix testis (hydatid of Morgagni)

Normal testis

Efferent ducts

Leydig cells

Rete testis

Seminiferous tubules