Mediastinum testis (English spelling) mediastinumtestis

…Each is a flattened ellipsoid about the size of a broad bean. During the early stages of fetal development, it is located in the abdominal cavity, but at around the seventh month of fetal development, it descends along with the vas deferens through the inguinal canal into the scrotum. It is surrounded by a connective tissue membrane called the tunica albuginea, but at its posterior edge, the tunica albuginea thickens and is called the mediastinum testis. The testicular septum radiates from the mediastinum testis toward the tunica albuginea, dividing the testis into about 250 lobules. …

*Some of the terminology explanations that mention "mediastinum testis" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…それぞれソラマメくらいの大きさの扁平な楕円体で，胎生初期には腹腔内にあるが胎生7ヵ月ごろに精管とともに鼠径管（そけいかん）を通って陰囊内へ下降する。白膜tunica albugineaと呼ばれる結合組織性の膜につつまれるが，後縁では白膜は厚くなっており精巣縦隔mediastinum testisと呼ばれる。精巣縦隔から白膜へむけて放射状に精巣中隔が出て，精巣を約250個の小葉にわける。…

※「mediastinum testis」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報