Most cases of testicular cancer (95%) are of germ cell origin. The rest are derived from Sertoli cells or Leydig cells. Examine the electron micrographs of Sertoli cells (Fig. 18.8).

Explain the relationship of Sertoli cells to developing germ cells and the nature of the "blood-testis barrier."

On slides 119 and 155, examine the interstitial tissue between tubules and identify the large interstitial cells (Leydig cells) (Fig. 21-4).

What is the function of Leydig cells and what hormone stimulates this function?

Back on slide 55, look at other regions of the section and identify the rete testis, in dense connective tissue but having an irregular arrangement of spaces lined by simple cuboidal epithelium (Fig. 21-9). On slide 40 identify the efferent ductules, loose tubules again lined with tall ciliated epithelial cells (Fig. 21-10).

What happens in the rete testis and how does the epithelial lining accomplish this?

What is the function of the cells lining the efferent ductules?

The epididymis is a long convoluted duct with smooth muscle. Examine the beginning or head of the epididymis and adjacent efferent ductules on slide 40 and the tail of the epididymis (leading to the vas deferens) on slide 39. Identify the tall columnar or pseudostratified epithelium with stereocilia and the stored spermatozoa in the lumen (Fig. 21-11).

What apical structures are found on the columnar cells lining the epididymis and what is its function?

Now for the vas deferens and seminal vessicles.