睾丸的内胚层窦肿瘤（卵黄囊肿瘤）由原始生殖细胞构成，这些细胞形成血管球或胚芽样结构。儿童多发，但总体来说是少见的。
An endodermal sinus tumor (yolk sac tumor) of the testis is shown composed of primitive germ cells that form glomeruloid or embryonal-like structures. These tumors are most frequent in children, but overall they are rare.
