The lobules are conical in shape, the base being directed toward the circumference of the organ, the apex toward the mediastinum testis.

The mediastinum testis is a network of fibrous connective tissue that extends from the upper to near the lower extremity of the testis, and is wider above than below.

It is applied to the tunica vasculosa over the glandular substance of the testis, and, at its posterior border, is reflected into the interior of the gland, forming an incomplete vertical septum, called the mediastinum testis (corpus Highmori).

Each lobule is contained in one of the intervals between the fibrous septa which extend between the mediastinum testis and the tunica albuginea, and consists of from one to three, or more, minute convoluted tubes, the tubuli seminiferi.