The processus vaginalis is the clinical term for a process that is characterized by the development of a diverticulum, or a protrusion or pouch, of the peritoneum. Its full medical term is actually processus vaginalis peritonei, which reflects the part of the body involved. Although its name suggests a process restricted to the reproductive and urinary organs of females, the processus vaginalis affects males as well. It is considered one of the developments that comprise embryology, the branch of medicine concerning the formation and early growth of living organisms.
The peritoneum is a smooth and thin layer of cells most commonly identified as lining the abdominal cavity. Known as a serous membrane because it contains a pale and yellow substance called serous fluid, it also lines the male gonad known as the testes. The processus vaginalis begins around the 12th week of pregnancy. This is before the testes begin their descent from the abdomen to the scrotum with the aid of the embryonic structure known as the gubernaculum.
A few weeks before or after birth, the closure that forms the testes is complete. The portion that remains is called the tunica vaginalis. In total, the processus vaginalis lasts for about 12 weeks.
The tunica vaginalis consists of two parts. The visceral lamina, clinically known as the lamina visceralis, connects the testes with the epididymis, a tube used for transporting sperm. The parietal lamina, or lamina parietalis, is the larger part of the tunica vaginalis. The interval between both parts forms the peritoneal pouch's cavity.
In females, the failure of the pouch to close results in its extension to the labia majora, which is analogous to the scrotum in males. This condition is known as the Canal of Nuck, or Nuck's diverticulum. It is named after a 17th century Dutch anatomist named Antonius Nuck van Leiden, who did extensive research on the human reproductive system.
The lack of an enclosure from the vaginal process, or the presence of tunica vaginalis, can result in certain medical conditions. Perhaps the most common of them is a hydrocele. This is the accumulation of serous fluid from the peritoneal pouch. Males can develop a hematocele, which is the accumulation of blood in the testes. Other conditions that result from processus vaginalis include cysts and hernias. These abnormalities can usually be treated using surgical procedures.