Histology of the testis

Microscopically the testis is divided into about 370 testicular lobules (Lobuli testis), which are separated from each other by connective tissue septa. Each testicular lobe consists of 1 to 4 testicular tubules (Tubuli seminiferi), which are strongly compressed by tangling. The testicular tubules are formed by two cell types, the Sertoli cells and the germ cells of sperm development.

The Sertoli cells form a supporting environment for the germ cells from which sperm develop. The testicular tubules then continue via short straight tubules (Tubuli recti) into reticular tubules (Rete testis). These lead into further duct systems, the Ductuli efferentes, which are located at the upper pole of the testis.

These are followed by the epididymal and deferent ducts. In its entirety the duct system of the testis is enclosed by a coarse capsule of connective tissue, the tunica albuginea. A two-layered serous sheath (tunica vaginalis) is fused with this capsule.

The inner leaf adjacent to the tunica albuginea is called epiorchium, the outer one is called periorchium. In between there is a slit containing some fluid (Cavitas serosa scroti). Two fasciae (fascia spermatica interna and externa) lie on top of it, the tunica dartos consisting of smooth muscles, the sclera and finally the scrotal skin of the scrotum.

The tissue between the duct system is composed of loose connective tissue, blood and lymph vessels and intermediate cells. These intermediate cells of the testis are called Leydig cells. They serve the production of sex hormones, the androgens.

How large is a normal testicle?

The exact size and volume of the testicles can be determined by means of an ultrasound examination. The standard for testicle size in adult men is given with the following values: The length is usually between 4-5cm. The width is 2-3cm.

The normal volume is 15-35ml in adults. In boys the norm values depend on the respective phase of development and puberty. In medicine, these are classified according to the so-called Tanner stages.

Before puberty, in stage I, the testicular volume is less than 1.5ml.
As development progresses, the testicles in stage II enlarge to a volume of 6ml.
In stage III and IV the penis size increases together with the volume of the testicles, which is then 12-20ml.
Once stage V is reached, the development is finally complete and the values correspond to those of an adult.