Sinus tubercle (also known as sinual tubercle or Müllerian eminence) is the proliferation of

endoderm Endoderm is the innermost of the three primary germ layers in the very early embryo. The other two layers are the ectoderm (outside layer) and mesoderm (middle layer). Cells migrating inward along the archenteron form the inner layer of the gastr ...

induced by the

paramesonephric ducts The paramesonephric ducts (or Müllerian ducts) are paired ducts of the embryo in the reproductive system of humans and other mammals that run down the lateral sides of the genital ridge and terminate at the sinus tubercle in the primitive urogen ...

. It is located in the developing fetus between the orifices of the

mesonephric ducts The mesonephric duct, also known as the Wolffian duct, archinephric duct, Leydig's duct or nephric duct, is a paired organ that develops in the early stages of embryonic development in humans and other mammals. It is an important structure that pl ...

on the

urogenital sinus The urogenital sinus is a body part of a human or other Placentalia, placental only present in the development of the urinary system, development of the urinary and development of the reproductive organs, reproductive organs. It is the ventral p ...

. The

uterovaginal primoridium The human female reproductive system is made up of the internal and external sex organs that function in the Human reproduction, reproduction of new offspring. The reproductive system is immature at birth and develops at puberty to be able to ...

, which is a fusion of the caudal ends of

, contacts the dorsal wall of the

and, induces the formation of the sinus tubercle. This occurs in both sexes: *In the female, the

mesonephric duct The mesonephric duct, also known as the Wolffian duct, archinephric duct, Leydig's duct or nephric duct, is a paired organ that develops in the early stages of embryonic development in humans and other mammals. It is an important structure that pl ...

loses all association with the gonad and disappears. The sinus tubercle then gives rise to the

sino-vaginal bulb The sinovaginal bulb is a transitional structure in the development of female genitalia, and is one of a pair of endodermal outgrowths of the urogenital sinus, which later fuse to form the lower part of the vagina. The lower third of the vagina is d ...

s and, when it later becomes solid it is referred to as the

vaginal plate In mammals and other animals, the vagina (: vaginas or vaginae) is the elastic, muscular reproductive organ of the female genital tract. In humans, it extends from the vulval vestibule to the cervix (neck of the uterus). The vaginal introit ...

. It likewise gives rise to the

hymen The hymen is a thin piece of mucosal tissue that surrounds or partially covers the vaginal opening. A small percentage of females are born with hymens that are imperforate and completely obstruct the vaginal canal. It forms part of the vulva ...

, which eventually breaks down in most cases. * In the males, the sinus tubercle gives rise to the

seminal colliculus The seminal colliculus (Latin ''colliculus seminalis''), or verumontanum, of the prostatic urethra is a landmark distal to the entrance of the ejaculatory ducts (on both sides, corresponding vas deferens and seminal vesicle feed into correspondin ...

References

* *Moore Persaud, ''Medical embryology'' 2003 {{Development of urinary and reproductive systems Animal developmental biology Embryology