The tunica vaginalis is a structure within the testicles. It consists of two layers of serous membranes which cover the tunica vaginalis albuginea, a layer of fibrous material which wraps around the testes. Several layers of tissue are involved in the structure of the scrotum to support and protect the contents, and the tunica vaginalis is one of them. Numerous detailed drawings of scrotal anatomy are available for people who are interested in learning more about the development and structure of the testes.
This layer of tissue arises from the vaginal process during fetal development. It starts as a pouch in the peritoneum which gradually moves downward and shifts to accommodate the development of the testes. This occurs in response to hormone levels during development which also predicate the formation of the genitalia. In women, sometimes the vaginal process fails to develop normally during fetal development, and as a result they may develop a structure known as the Canal of Nuck, and they can be prone to cysts and other problems.
Abnormalities in fetal development for men can lead to a variety of issues within the tunica vaginalis. Sometimes boys are born with a hernia because the structure failed to close and form properly, and they can also develop hydroceles and cysts caused by variations in the tunica vaginalis. This is usually visible on a medical imaging study such as an ultrasound, in which the anatomy can be visualized by an experienced radiologist who is familiar with variations in anatomical structure which can lead to medical issues.
If the tunica vaginalis fails to develop properly, a doctor may recommend surgery to correct the problem. Surgery is recommended if the variation causes pain, discomfort, or concerns about fertility. More benign variations are usually left to their own devices, as surgery can be traumatic and risky. If there is no reason to perform surgery, it is generally viewed as not worth the risk.
Because this structure arises from the peritoneum, it is lined with mesothelium. It is possible for men to develop mesothelioma in the tunica vaginalis, although this is very rare. If this cancer does develop, there are several treatment options available which men can discuss with their oncologists. Success of treatment varies, depending on when the cancer is identified and how quickly and aggressively it is treated. As a general rule, the chances of success are higher when the cancer is spotted early.