Smegma (

Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...

σμῆγμα : ''smēgma'') is a combination of

shed A shed is typically a simple, single-story roofed structure that is used for hobbies, or as a workshop in a back garden or on an allotment. Sheds vary considerably in their size and complexity of construction, from simple open-sided ones de ...

skin cells Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different de ...

, skin oils, and moisture. It occurs in both male and female mammalian genitalia. In females, it collects around the

clitoris The clitoris ( or ) is a female sex organ present in mammals, ostriches and a limited number of other animals. In humans, the visible portion – the glans – is at the front junction of the labia minora (inner lips), above the ope ...

and in the folds of the

labia minora The labia minora (Latin for 'smaller lips', singular: ''labium minus'', 'smaller lip'), also known as the inner labia, inner lips, vaginal lips or nymphae are two flaps of skin on either side of the human vaginal opening in the vulva, situated be ...

; in males, smegma collects under the

foreskin In male human anatomy, the foreskin, also known as the prepuce, is the double-layered fold of skin, mucosal and muscular tissue at the distal end of the human penis that covers the glans and the urinary meatus. The foreskin is attached to the g ...

Females

The accumulation of

sebum A sebaceous gland is a microscopic exocrine gland in the skin that opens into a hair follicle to secrete an oily or waxy matter, called sebum, which lubricates the hair and skin of mammals. In humans, sebaceous glands occur in the greatest nu ...

combined with dead skin cells forms smegma. ''Smegma clitoridis'' is defined as the secretion of the

apocrine glands Apocrine () glands are a type of exocrine gland, which are themselves a type of gland, i.e. a group of cells specialized for the release of secretions. Exocrine glands secrete by one of three means: holocrine, merocrine and apocrine. In apocri ...

of the clitoris, in combination with desquamating epithelial cells. Glands that are located around the clitoris, the labia minora, and the labia majora secrete

. If smegma is not removed frequently it can lead to clitoral adhesion which can make clitoral stimulation (such as masturbation) painful (clitorodynia).

Males

In males, smegma helps keep the

glans The glans (, plural "glandes" ; from the Latin word for "acorn") is a vascular structure located at the tip of the penis in male mammals or a homologous genital structure of the clitoris in female mammals. Structure The exterior structure ...

moist and facilitates

sexual intercourse Sexual intercourse (or coitus or copulation) is a sexual activity typically involving the insertion and thrusting of the penis into the vagina for sexual pleasure or reproduction.Sexual intercourse most commonly means penile–vaginal penetrat ...

by acting as a lubricant. Smegma, itself, is completely benign, but uncircumcised "men with

phimosis Phimosis (from Greek language, Greek φίμωσις ''phimōsis'' 'muzzling'.) is a condition in which the foreskin of the Human penis, penis cannot stretch to allow it to be pulled back past the Glans penis, glans. A balloon-like swelling under ...

have an increased risk of penile cancer." Smegma was originally thought to be produced by

sebaceous gland A sebaceous gland is a microscopic exocrine gland in the skin that opens into a hair follicle to secrete an oily or waxy matter, called sebum, which lubricates the hair and skin of mammals. In humans, sebaceous glands occur in the greatest number ...

s near the

frenulum A frenulum (or frenum, plural: frenula or frena, from the Latin ''frēnulum'', "little bridle", the diminutive of ''frēnum'') is a small fold of tissue that secures the motion of a mobile organ in the body. In human anatomy Frenula on the h ...

called Tyson's glands; however, subsequent studies have failed to find these glands. Joyce Wright states that smegma is produced from minute microscopic protrusions of the mucosal surface of the foreskin and that living cells constantly grow towards the surface, undergo fatty degeneration, separate off, and form smegma. Parkash ''et al.'' found that smegma contains 26.6% fats and 13.3% proteins, which they judged to be consistent with necrotic epithelial debris. Newly produced smegma has a smooth, moist texture. It is thought to be rich in

squalene Squalene is an organic compound. It is a triterpenoid with the formula C30H50. It is a colourless oil, although impure samples appear yellow. It was originally obtained from shark liver oil (hence its name, as ''Squalus'' is a genus of sharks). A ...

and contain prostatic and seminal secretions, desquamated

epithelial cells Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellula ...

, and the mucin content of the urethral glands of Littré. Smegma contains

cathepsin B Cathepsin B belongs to a family of lysosomal cysteine proteases known as the cysteine cathepsins and plays an important role in intracellular proteolysis. In humans, cathepsin B is encoded by the ''CTSB'' gene. Cathepsin B is upregulated in ce ...

lysozymes Lysozyme (EC 3.2.1.17, muramidase, ''N''-acetylmuramide glycanhydrolase; systematic name peptidoglycan ''N''-acetylmuramoylhydrolase) is an antimicrobial enzyme produced by animals that forms part of the innate immune system. It is a glycosid ...

, chymotrypsin, neutrophil elastase and

cytokines Cytokines are a broad and loose category of small proteins (~5–25 kDa) important in cell signaling. Cytokines are peptides and cannot cross the lipid bilayer of cells to enter the cytoplasm. Cytokines have been shown to be involved in autocrin ...

, which aid the immune system. According to Wright, little smegma is produced during childhood, although the foreskin may contain sebaceous glands. She also says that production of smegma increases from adolescence until sexual maturity when the function of smegma for lubrication assumes its full value, and from middle-age production starts to decline and in old age virtually no smegma is produced. Jakob Øster reported that the incidence of smegma increased from 1% among 6- to 7-year-olds and 8- to 9-year-olds to 8% among 14- to 15-year-olds and 16- to 17-year-olds (an overall incidence of 5%). There is no evidence that smegma, itself, causes penile cancer, but it may harbor cancerous pathogens, like

HPV Human papillomavirus infection (HPV infection) is caused by a DNA virus from the '' Papillomaviridae'' family. Many HPV infections cause no symptoms and 90% resolve spontaneously within two years. In some cases, an HPV infection persists and re ...

, and its presence over a long period of time may irritate and inflame the penis, which may increase the risk of cancer. It may also make it harder to see very early cancers.

Other animals

In healthy animals, smegma helps clean and lubricate the genitals. In veterinary medicine, analysis of this smegma is sometimes used for detection of urogenital tract pathogens, such as ''

Tritrichomonas foetus ''Tritrichomonas foetus'' is a species of single-celled flagellated parasites that is known to be a pathogen of the bovine reproductive tract as well as the intestinal tract of cats. In cattle, the organism is transmitted to the female vagina ...

''. Accumulation of smegma in the equine preputial folds and the urethral fossa and

urethral diverticulum A urethral diverticulum is a condition where the urethra or the periurethral glands push into the connective tissue layers ( fascia) that surround it. Signs and symptoms Urethral diverticula are often asymptomatic and symptoms that are present t ...

can form large "beans" and promote the carriage of ''

Taylorella equigenitalis Introduction and overview ''Taylorella equigenitalis'' is a Gram-negative, non-motile, microaerophilic bacterium of the genus '' Taylorella'', and the causative agent of contagious equine metritis (CEM) in horses. Phylogeny of ''T. equigenital ...

'', the causative agent of

contagious equine metritis Contagious equine metritis (CEM) is a type of metritis (uterine inflammation) in horses that is caused by a sexually transmitted infection. It is thus an equine venereal disease of the genital tract of horses, brought on by the '' Taylorella equig ...

. Some equine veterinarians have recommended periodic cleaning of male genitals to improve the health of the animal.

References

External links

* * * {{cite book , doi=10.1007/978-3-030-37621-5_17 , chapter=Smegma , title=Normal and Abnormal Prepuce , year=2020 , last1=Fahmy , first1=Mohamed A. Baky , pages=153–161 , isbn=978-3-030-37620-8 , s2cid=243171662 Excretion Exocrine system Mammal female reproductive system Mammal male reproductive system

Females

Males

Other animals

See also

References

External links