What is the Tunica Vaginalis?

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  • Written By: Mary McMahon
  • Edited By: O. Wallace
  • Last Modified Date: 12 September 2019
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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.


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Post 4

@Hawthorne - VivAnne's on the right track -- embryos don't start out female any more than they start out male. And yes, this stuff is quite useful for transgendered people or people who want to become transgendered, although it is in a limited capacity.

See, becoming transgendered involves alteration surgeries and hormone therapy. Hormones are in charge of everything during an embryo's development, but by the time you're an adult your bones and everything formed as male or female a long time ago.

That means no amount of hormone therapy is going to change male bone structure to female or vice versa, so transgendered male-to-female people will always be at least a bit recognizable as their original gender

thanks to larger hands and squarer shoulders.

Hormone therapy might some day allow a transgendered woman's body to produce eggs to have children, though. That's still pretty impressive.

Back to the subject at hand...if the tunica vaginalis was formed improperly enough, could a person in theory be born with both a vagina and a penis?

Post 3

@VivAnne - Whoa. So basically, human starts with no gender, then they're both genders, then they end up being one or the other? Weird, I never knew that.

I always heard that embryos started out female and then certain hormones make them male -- you know, like they talked about for the dinosaurs in Jurassic Park? Not that I first learned it there as far as humans go. My parents told me that embryos started female.

Your explanation actually makes a lot more sense. If embryos actually started out blank with "indifferent gonads" and switch to a gender by the time they're done developing, but have aspects of both genders at one point, that explains why some people are born

with aspects of both genders and no technical gender of their own.

It's not because the "maleness" didn't take hold that well, it's because neither gender was "decided on". Hmm. This kind of information could be pretty useful for people who want to change their genders, couldn't it?

Post 2

@TheGraham - It seems weird to have a word similar to "vagina" used to refer to a male body trait -- especially one in the testicles -- but there is a method to this madness.

Did you know that, up until about six weeks of age, human beings have no gender? A few weeks before the X or Y chromosomes initiate and "choose" a gender for the baby, the forming body grows sex organs called the "indifferent gonads" (not kidding, as funny as that sounds) which will eventually turn into either ovaries or testicles.

Even though the body hasn't determined a gender yet, the growing baby needs to develop before it can even become a fetus, so to save on time

it grows internal sexual features to be both male and female. These are called the Mullerian and Wolffian ducts, respectively.

Anyway, at around six weeks of age the baby becomes one gender or the other, and in addition to the X or Y chromosomes it secretes a substance that inhibits the sexual organs of the opposite gender from developing. This makes the Mullerian ducts wither away if the baby is male, and the Wolffian ducts wither away if it turns out to be female.

What all of this means is that problems with the tunica vaginalis and testis are probably caused by the Mullerian ducts not disappearing entirely. Phew!

Post 1

I clicked this article because I was curious what exactly the tunica vaginalis is; I assumed it had to do with female anatomy, and certainly didn't expect it to be a male body area inside the testicles!

That seems kind of backward, doesn't it? Do women have any genital traits with the word "testes" in them, then?

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