20,000 Nerve Endings

The foreskin is the most sensitive part of the penis. It contains:

    10,000 nerve endings, or
    20,000 nerve endings (the most frequently cited statistic), or
    20,000 to 70,000 (the most recently cited statistic).

This statement about foreskin sensitivity is somewhat recent. It is one of the most popular statements made to justify the campaign against routine infant circumcision – and one of the most difficult to verify!

Who came up with the original number?

The number was published in a popular mothering magazine in an article written by pediatrician Dr. Paul Fleiss (“The Case Against Circumcision” by Paul M. Fleiss, MD, published in Mothering: The Magazine of Natural Family Living, Winter 1997, pp. 36-45). Dr. Fleiss has been campaigning against routine neonatal (newborn and infant) circumcisions for years. He is also a strong advocate of breastfeeding and a medical advisor to La Leche League, the international organization promoting it. In that article, Dr. Fleiss made the statement about the 20,000 nerve endings as one of his many reasons to leave the foreskin intact. Although he did not do the research that came up with the number, he did cite earlier research that had been done, including research that had been done as early as the 1930s. Where he got the exact number of 20,000 is unknown, since no study has actually counted the number. There have been a number of studies about the nerves in a foreskin, but most are from 50, 80 and even 200 years ago.

According to one legendary study, the number is from a multiplication of the number of nerve endings on one square centimeter (212 endings, to be exact; 2 of which are Meissner corpuscles, the ending attributed to sensitivity in the skin to touch) that was taken from a cadaver. No one knows the age of the cadaver, the cause of death or where on the foreskin the sample came from. In fact, no one can find the original study, including this experienced journalist and two research librarians. It is simply nowhere to be found on the Internet, at least, despite hours and hours (and hours!) of research. Only one rebuttal (seen here: Sloppy scholarship and the anti-circumcision crusade.) could be found.

Other studies, including the one cited by Fleiss (H.C. Bazett, et. Al., “Depth, Distributioin and Probably Identification in the Prepuce of Sensory End-Organs Concerned in Sensations of Temperature and Touch; Thermometric Conductivity,” Archives of Neurology and Psychiatry 27 (1932), pp. 489-517) show a plethora of nerves in the foreskins but never an exact counting of them. Nor can an agreement – scientifically, that is – on the size of the foreskin on which the numbers are based. Some researchers claim that an average foreskin measures 12 to 16 square inches; others say it is half that.

There are still other studies, but again, not a single one actually gives an average count. And again, there is some skepticism that the number is a pure exaggeration and not even based on scientific studies, especially the last number in the statement that has recently been quoted: 20,000 to 70,000 nerve endings on an average foreskin.

One, major problem with the number, is that the foreskin, like all skin, contains at least 7 different types of nerve endings, not just the ones that stimulate the foreskin and produce sexual stimulation, and eventually, produce orgasm and ejaculation. And Dr. Fleiss (like a number of other circumcision researchers, including Dr. Bollinger, who cited the 117 infant mortalities in the U.S. due to routine circumcision) is an active, anti-circumcision physician which can make him vulnerable to bias.

Can sensitivity to touch on the foreskin or on the glans be measured?

A major goal of those who quote the 10,000, 20,000 or 70,000 number is to use it as evidence that the foreskin is highly sensitive, in particular, sensitive to touch (as say, to temperature). Fortunately, there are other ways to measure touch, especially the kind of touch that tells the brain sex is coming, and thus, to make an argument not to remove the foreskin. So for now, forget the number of nerve endings and look instead at studies that have measured the sensitivity – of both the foreskin and of the glans – then compared that measured sensitivity to other parts of the body that also have nerve endings that are sensitive to touch. Fortunately, the source of these studies is more easily verifiable since they have all been published in major medical journals, and therefore, easily found on the Internet. What is interesting to note, though, is that the results vary from one study to another, and in fact, tend to refute the results of each other!

Two studies often quoted were each done in the past decade or so. What is interesting is that as mentioned previously, one study refutes the other. Thus, one study found that the foreskin was the most sensitive location on the penis, and that when removed by circumcision, the glans that lies underneath a foreskin showed less sensitivity in general. The other study looked at the Meissner’s corpuscles in eight parts of the body where Meissner corpuscles are concentrated, and therefore, more sensitive to touch than other body parts. What the team of researchers found is that the least sensitive part (to touch) of all 8 body parts studied – happened to be both the foreskin and the glans. In contrast, the most sensitive body part was located on the fingertips.

One more issue to consider

One more fact to consider is the body’s ability to substitute. For example, people whose sight is diminished or even blinded may experience an increase in their sense of touch or sound. Likewise, people who grow deaf may, in turn, grow more visually discriminating. Men circumcised as adults have been surveyed. Many report being more sexually sensitive after their circumcision. Perhaps losing a foreskin’s touch nerve endings helps them gain more sensitivity elsewhere, and in particular, on their glans. And note that other men lament their circumcision as adults, reporting less sensitive. Even worse, some men detest it. So much depends on the individual circumstance to draw a conclusion here, despite the best intentions of both anti-circs and pro-circs.

To sum things up

First, it might be prudent to be skeptical about the exact number – average, or mean – cells on a foreskin. Maybe the number of nerve endings is accurate. But maybe, the number isn’t. What is certain is that more research is needed, research that can be replicated, and perhaps, research done on larger groups and over longer periods, since nerve cells, as we have learned previously, tend to decrease with age.

Secondly, even results of studies showing sensitivity to the foreskin and to the glans make it difficult, if not impossible, to draw a firm conclusion.

Finally, given the uncertainty of some of the data, the polarity of feelings about what data does exist, the polarity of feelings about being circumcised, it is difficult to look at the number often stated as truly factual, or to use it as evidence to use in a decision about circumcision.