Anatomy of the testes and the epididymis

Anatomy of the testes and the epididymisAnatomical features of the testes and the epididymis. Functions. Blood supply and innervation.
~ 5 min

In this note, we will consider the anatomy of the testis and the epididymis.

Testis

The testis (testis), or testicle is a paired ovoid-shaped organ located inside the scrotum. The production of spermatozoa and male sex hormones occurs in the testis.

Testis (testis)
Testis (testis)
Testis (testis)
Testis (testis)

Testicles are formed in the abdominal cavity and descend into the scrotum during embryogenesis.

There they are suspended on the spermatic cord (funiculus spermaticus)

Spermatic cord (funiculus spermaticus)
Spermatic cord (funiculus spermaticus)
Spermatic cord (funiculus spermaticus)
Spermatic cord (funiculus spermaticus)
Spermatic cord (funiculus spermaticus)
Spermatic cord (funiculus spermaticus)

The left testicle is usually slightly lower than the right one.

There are two surfaces of the testis:

1. The medial surface (facies medialis)

Medial surface (facies medialis)
Medial surface (facies medialis)

2. The lateral surface (facies lateralis)

Lateral surface (facies lateralis)
Lateral surface (facies lateralis)
Lateral surface (facies lateralis)
Lateral surface (facies lateralis)

There are also borders of the testis:

1. The anterior border (margo anterior)

Anterior border (margo anterior)
Anterior border (margo anterior)
Anterior border (margo anterior)
Anterior border (margo anterior)

2. The posterior border (margo posterior)

Posterior border (margo posterior)
Posterior border (margo posterior)

And two poles:

1. The superior pole (extremitas superior)

Superior pole (extremitas superior)
Superior pole (extremitas superior)

2. The inferior pole (extremitas inferior)

Inferior pole (extremitas inferior)
Inferior pole (extremitas inferior)
Inferior pole (extremitas inferior)
Inferior pole (extremitas inferior)

The testis is placed in a capsule, which consists of three layers.

The vascular layer (tunica vasculosa) is the internal layer

The tunica albuginea (tunica albuginea) is the middle layer

Tunica albuginea (tunica albuginea)
Tunica albuginea (tunica albuginea)
Tunica albuginea (tunica albuginea)
Tunica albuginea (tunica albuginea)

The tunica vaginalis (tunica vaginalis), namely its visceral layer, is the external layer

Tunica vaginalis (tunica vaginalis)
Tunica vaginalis (tunica vaginalis)
Tunica vaginalis (tunica vaginalis)
Tunica vaginalis (tunica vaginalis)

Along the posterior border of the organ there is the epididymis (epididymis)

Epididymis (epididymis)
Epididymis (epididymis)
Epididymis (epididymis)
Epididymis (epididymis)
Epididymis (epididymis)
Epididymis (epididymis)

There is a cavity between the testis and the epididymis called the sinus of the epididymis (sinus epididymidis)

Sinus of the epididymis (sinus epididymidis)
Sinus of the epididymis (sinus epididymidis)
Sinus of the epididymis (sinus epididymidis)
Sinus of the epididymis (sinus epididymidis)

In this area, there is also a thickening of the tunica albuginea, which is called mediastinum (mediastinum testis)

Mediastinum (mediastinum testis)
Mediastinum (mediastinum testis)
Mediastinum (mediastinum testis)
Mediastinum (mediastinum testis)

Septa (septula testis) extend from it deep into the parenchyma (parenchyma testis).

Septa (septula testis)
Septa (septula testis)
Septa (septula testis)
Septa (septula testis)

They divide the testis into lobules (lobuli testis), each of which contains convoluted seminiferous tubules (tubuli seminiferi contorti).

Lobules (lobuli testis)
Lobules (lobuli testis)
Lobules (lobuli testis)
Lobules (lobuli testis)

These tubules are lined with spermatogenic epithelium, in which spermatozoa are produced.

The wall of the convoluted seminiferous tubules contains spermatogenic cells. Between these cells, there are supporting epithelial cells (sustentocytes), or Sertoli cells. These cells, in addition to providing support, also provide protection and secrete substances that regulate spermatogenesis. They will also divide the seminiferous tubule into two parts: basal and adluminal, which form the blood-testis barrier separating spermatogenic cells from the immune system. In addition, each lobule contains Leydig cells that produce testosterone.

Together, spermatogenic cells and sustentocytes form the epithelial spermatogenic layer. Their large number determines the constant production of seminal fluid. This layer is covered with smooth muscle and fibrous cells, which contract and push the germ cells out of the convoluted tubules of the testes.

The convoluted seminiferous tubules turn into straight tubules (tubuli seminiferi recti), and those in turn form the rete testis in the mediastinum (rete testis).

From it, the efferent ductules (ductuli efferentes testis) pass into the epididymis.

Epididymis

Let’s consider the anatomy of the epididymis

Epididymis (epididymis)
Epididymis (epididymis)
Epididymis (epididymis)
Epididymis (epididymis)
Epididymis (epididymis)
Epididymis (epididymis)

It has the following parts:

  • The head (caput epididymidis)
Head of the epididymis (caput epididymidis)
Head of the epididymis (caput epididymidis)
Head of the epididymis (caput epididymidis)
Head of the epididymis (caput epididymidis)
  • The body (corpus epididymidis)
Body of the epididymis (corpus epididymidis)
 Body of the epididymis (corpus epididymidis)
Body of the epididymis (corpus epididymidis)
 Body of the epididymis (corpus epididymidis)
  • The tail (cauda epididymidis)
Tail of the epididymis (cauda epididymidis)
Tail of the epididymis (cauda epididymidis)

There is a small depression between the testis and the epididymis called the sinus of the epididymis (sinus epididymidis)

Sinus of the epididymis (sinus epididymidis)
Sinus of the epididymis (sinus epididymidis)
Sinus of the epididymis (sinus epididymidis)
Sinus of the epididymis (sinus epididymidis)

The organ is covered with the same membranes as the testis.

The already mentioned efferent ductules pass into the duct of the epididymis (ductus epididymidis), which begins in the head.

Eventually, the duct of the appendix passes into the ductus deferens / vas deferens (ductus deferens).

Vas deferens (ductus deferens)
Vas deferens (ductus deferens)
Vas deferens (ductus deferens)
Vas deferens (ductus deferens)
Vas deferens (ductus deferens)
Vas deferens (ductus deferens)

The system of tubules of the appendix is a reservoir for spermatozoa, in which they mature. The epididymis is an androgen-dependent secretory organ, which means that its work depends on the amount of testosterone in the blood.

Rudimentary structures

In the testis and epididymis, there are several rudimentary formations, remaining after embryogenesis.

The remainder of Müllerian duct: this is the appendix of the testis (appendix testis)

Appendix of the testis (appendix testis)
Appendix of the testis (appendix testis)
Appendix of the testis (appendix testis)
Appendix of the testis (appendix testis)

The remainder of Wolffian duct: this is the appendix of the epididymis (appendix epididymis)

Appendix of the epididymis (appendix epididymis)
Appendix of the epididymis (appendix epididymis)
Appendix of the epididymis (appendix epididymis)
Appendix of the epididymis (appendix epididymis)

The remainder of the Wolffian body: this is the appendix of the paradidymis (paradidymis)

These rudimentary structures are well expressed in children up to 10 years old, and then gradually reduced.

Blood supply

Arterial blood enters the testicle and epididymis from the testicular artery (branch of the abdominal aorta) and the artery of the ductus deferens (branch of the umbilical artery). And also, partially from the cremasteric artery.

Venous drainage

Venous blood drains through the testicular veins forming the pampiniform plexus.

Lymph drainage

Lymph drains from the testis through the lymphatic vessels as part of the spermatic cord to the lumbar lymph nodes.

Innervation

The testis and epididymis are innervated by the nerves from the testicular plexus.

Dictionary

Anatomy of the testes and the epididymis

Testis
testis
Medial surface
facies medialis
Lateral surface
facies lateralis
Superior pole
extremitas superior
Inferior pole
extremitas inferior
Anterior border
margo anterior
Posterior border
margo posterior
Spermatic cord
funiculus spermaticus
Epididymis
epididymis
Sinus of the epididymis
sinus epididymidis
Appendix testis
appendix testis
Parenchyma of the testis
parenchyma testis
Tunica albuginea
tunica albuginea
Septa testis
septula testis
Lobules of the testis
lobuli testis
Mediastinum of the testis
mediastinum testis
Seminiferous tubules
tubuli seminiferi contorti
Spermium
spermium
Seminal fluid
sperma
Straight tubules of the testis
ductuli rectus testis
Rete testis
rete testis
Efferent ductules of thetestis
ductuli efferentes testis
Ductules of the testis
ductuli efferentes testis
Duct of the epididymis
ductus epididymidis
Ductus deferens
ductus deferens
Male urethra
urethra masculine
Ejaculatory duct
ductus ejaculatorius
Testicular artery
a.testicularis
Artery to the ductus deferens
a.ductus deferentis
Cremasteric artery
a. cremasterica
Testicular vein
v.testicularis
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