Anatomy and histology

Testis and epididymis
General
Anatomy and histology

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

Revised: 5 April 2017, last major update August 2012

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

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

Table of Contents

Definition / general | Terminology | Diagrams / tables | Gross images | Microscopic (histologic) images

Cite this page: Anatomy and histology. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/testisanatomy.html. Accessed July 15th, 2017.

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

Terminology

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 Morgani):
- 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

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