The tunica vaginalis is a pouch of

serous membrane The serous membrane (or serosa) is a smooth epithelial membrane of mesothelium lining the contents and inner walls of body cavity, body cavities, which secrete serous fluid to allow lubricated sliding (motion), sliding movements between opposing ...

within the scrotum that lines the

testis A testicle or testis ( testes) is the gonad in all male bilaterians, including humans, and is Homology (biology), homologous to the ovary in females. Its primary functions are the production of sperm and the secretion of Androgen, androgens, p ...

and

epididymis The epididymis (; : epididymides or ) is an elongated tubular genital organ attached to the posterior side of each one of the two male reproductive glands, the testicles. It is a single, narrow, tightly coiled tube in adult humans, in length; ...

(visceral layer of tunica vaginalis), and the inner surface of the scrotum (parietal layer of tunica vaginalis). It is the outermost of the three layers that constitute the capsule of the testis, with the

tunica albuginea of testis The tunica albuginea is a dense, blue-white layer of fibrous tissue surrounding the testis. It is the middle of three envelopes forming the capsule of the testis; it is deep to the visceral layer of tunica vaginalis, and superficial to the tuni ...

situated beneath it. It is the remnant of a pouch of peritoneum which is pulled into the scrotum by the testis as it descends out of the abdominal cavity during foetal development.

Anatomy

Visceral layer

The visceral layer of tunica vaginalis of testis (lamina visceralis tunicae vaginalis testis) is the portion of the tunica vaginalis that covers the testis and

. It is the superficial-most of the three layers that constitute the capsule of the testis, with the

situated deep to it. Posteriorly, the visceral layer does not line the surface of the testis - instead, it passes onto the

where the latter attaches to the testis before continuing onto the inner surface of the scrotum as the parietal layer.

Parietal layer

The parietal layer of tunica vaginalis of testis (lamina parietalis tunicae vaginalis testis) is the portion of the tunica vaginalis that lines the inner surface of the

scrotum In most terrestrial mammals, the scrotum (: scrotums or scrota; possibly from Latin ''scortum'', meaning "hide" or "skin") or scrotal sac is a part of the external male genitalia located at the base of the penis. It consists of a sac of skin ...

. It is supported by the

internal spermatic fascia The internal spermatic fascia (infundibuliform fascia or Le deuxième fascia de Webster) is a thin layer, which loosely invests the spermatic cord. Structure The internal spermatic fascia is derived from the transversalis fascia. It is acquir ...

Cavity of the tunica vaginalis

The cavity of the tunica vaginalis (also: cavum of the tunica vaginalis, or cavum vaginale) is the cavity between the visceral layer and the parietal layer of tunica vaginalis. It is normally occupied by a small amount of clear, lightly coloured

fluid In physics, a fluid is a liquid, gas, or other material that may continuously motion, move and Deformation (physics), deform (''flow'') under an applied shear stress, or external force. They have zero shear modulus, or, in simpler terms, are M ...

. The volume of the fluid in the cavity may increase abnormally when lymphatic drainage is impeded (due to inflammation, neoplasm, or trauma).

Development

The tunica vaginalis is derived from the

vaginal process The vaginal process (or processus vaginalis) is an embryonic developmental outpouching of the parietal peritoneum. It is present from around the 12th week of gestation, and commences as a peritoneal outpouching. Sex differences In males, it prec ...

of the

peritoneum The peritoneum is the serous membrane forming the lining of the abdominal cavity or coelom in amniotes and some invertebrates, such as annelids. It covers most of the intra-abdominal (or coelomic) organs, and is composed of a layer of mesotheli ...

, which in the

fetus A fetus or foetus (; : fetuses, foetuses, rarely feti or foeti) is the unborn offspring of a viviparous animal that develops from an embryo. Following the embryonic development, embryonic stage, the fetal stage of development takes place. Pren ...

precedes the descent of the

testes A testicle or testis ( testes) is the gonad in all male bilaterians, including humans, and is homologous to the ovary in females. Its primary functions are the production of sperm and the secretion of androgens, primarily testosterone. The ...

from the

abdomen The abdomen (colloquially called the gut, belly, tummy, midriff, tucky, or stomach) is the front part of the torso between the thorax (chest) and pelvis in humans and in other vertebrates. The area occupied by the abdomen is called the abdominal ...

into the

. The vaginal process between the

abdominal inguinal ring The inguinal canal is a passage in the Anatomical terms of location#Anterior and posterior, anterior abdominal wall on each side of the body (one on each side of the Anatomical terms of location#Planes, midline), which in males, convey the spermat ...

and the superior part of the testis is then obliterated, usually leaving a string-like or cord-like remnant adjacent to the

spermatic cord The spermatic cord is the cord-like structure in males formed by the vas deferens (''ductus deferens'') and surrounding tissue that runs from the deep inguinal ring down to each testicle. Its serosal covering, the tunica vaginalis, is an exten ...

. If the vaginal process fails to obliterate, the communication between the peritoneal cavity and scrotum persists after birth, predisposing the individual to

indirect inguinal hernia An inguinal hernia or groin hernia is a hernia (protrusion) of abdominal cavity contents through the inguinal canal. Symptoms, which may include pain or discomfort especially with or following coughing, exercise, or bowel movements, are absent ...

, and

hydrocele testis A hydrocele testis is an accumulation of clear fluid within the cavum vaginale, the potential space between the layers of the tunica vaginalis of the testicle. It is the most common form of hydrocele and is often referred to simply as a "hydrocele ...

Diseases

Mesothelioma Mesothelioma is a type of cancer that develops from the thin layer of tissue that covers many of the internal organs (known as the mesothelium). The area most commonly affected is the lining of the lungs and chest wall. Less commonly the lini ...

Hydrocele A hydrocele is an accumulation of serous fluid in a body cavity. A hydrocele testis, the most common form of hydrocele, is the accumulation of fluids around a testicle. It is often caused by fluid collecting within a layer wrapped around the tes ...

* Cartilaginous bodies *

Hematocele A hematocele is a collections of blood in a body cavity or potential space. The term most commonly refers to the collection of blood in the tunica vaginalis around the testes, known as a ''scrotal hematocele''. Hematoceles can also occur in t ...

References

External links

Diagram at aspiruslibrary.org
* - "Inguinal Region, Scrotum and Testes: Tunic" * * () Mammal male reproductive system Scrotum {{Portal bar, Anatomy