The labioscrotal swellings (genital swellings or labioscrotal folds) are paired structures in the

mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

ian

embryo An embryo ( ) is the initial stage of development for a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sp ...

that represent the final stage of development of the caudal end of the external

genitals A sex organ, also known as a reproductive organ, is a part of an organism that is involved in sexual reproduction. Sex organs constitute the primary sex characteristics of an organism. Sex organs are responsible for producing and transporting ...

before sexual differentiation. In humans, the two swellings merge: * In the ''female'', they become the posterior labial commissure. The sides of the

genital tubercle A genital tubercle, phallic tubercle, or clitorophallic structure is a body of tissue present in the development of the reproductive system of amniotes. It forms in the ventral, caudal region of mammalian embryos of both sexes, and eventually ...

grow backward as the genital swellings, which ultimately form the

labia majora In primates, and specifically in humans, the labia majora (: labium majus), also known as the outer lips or outer labia, are two prominent Anatomical terms of location, longitudinal skin folds that extend downward and backward from the mons pubis ...

; the tubercle itself becomes the

mons pubis In human anatomy, and in mammals in general, the ''mons pubis'' or pubic mound (also known simply as the mons , and known specifically in females as the ''mons Venus'' or ''mons veneris'') is a rounded mass of fatty tissue found over the pubic s ...

. * In the ''male'', they become 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 ...

References

External links

"Development of Male External Genitalia", at mcgill.ca

Diagram at mhhe.com
* * {{Authority control Embryology of urogenital system