Genital tubercle

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Genital tubercle
Human genitalia - development 1.png
Stages in the development of the external sexual organs in the male and female.
Details
Precursor somatopleure [1]
Gives rise to clitoris or penis
System Reproductive system
Identifiers
Latin tuberculum phallicum; tuberculum genitale
TE tubercle_by_E5.7.4.0.1.0.1 E5.7.4.0.1.0.1
Anatomical terminology

A genital tubercle, phallic tubercle, or clitorophallic structure [2] is a body of tissue present in the development of the reproductive system of amniotes. [3] It forms in the ventral, caudal region of mammalian embryos of both sexes, and eventually develops into a primordial phallus. In the human fetus, the genital tubercle develops around week four of gestation, and by week nine, becomes recognizably either a clitoris or penis. This should not be confused with the sinus tubercle which is a proliferation of endoderm induced by paramesonephric ducts. Even after the phallus is developed (either a penile shaft or clitoral shaft), [4] the term genital tubercle remains, but only as the terminal end of it, [5] which develops into either the glans penis or the glans clitoridis.

Contents

In the development of the male fetus, the two sides of the tubercle approach ventrally forming a hollow tube that encloses the male urethra. The two glans wings merge in the midline forming the septum glandis. [6] In the female fetus, the tubercle is attached to the vestibular folds that remain unfused forming the labia minora and the vaginal vestibule in between. [7] The genital tubercle is sensitive to dihydrotestosterone and rich in 5-alpha-reductase, so that the amount of fetal testosterone present after the second month is a major determinant of phallus size at birth.

See also

Related Research Articles

<span class="mw-page-title-main">Clitoris</span> Erectile female sexual organ

In amniotes, the clitoris is a female sex organ. In humans, it is the vulva's most erogenous area and generally the primary anatomical source of female sexual pleasure. The clitoris is a complex structure, and its size and sensitivity can vary. The visible portion, the glans, of the clitoris is roughly the size and shape of a pea and is estimated to have at least 8,000 sensory nerve endings.

<span class="mw-page-title-main">Glans penis</span> End of the penis

In male human anatomy, the glans penis or penile glans, commonly referred to as the glans, is the bulbous structure at the distal end of the human penis that is the human male's most sensitive erogenous zone and primary anatomical source of sexual pleasure. The glans penis is present in the male reproductive organs of humans and most other mammals where it may appear smooth, spiny, elongated or divided. It is externally lined with mucosal tissue, which creates a smooth texture and glossy appearance. In humans, the glans is located over the distal ends of the corpora cavernosa and is a continuation of the corpus spongiosum of the penis. At the summit appears the urinary meatus and at the base forms the corona glandis. An elastic band of tissue, known as the frenulum, runs on its ventral surface. In men who are not circumcised, it is completely or partially covered by a fold of skin called the foreskin. In adults, the foreskin can generally be retracted over and past the glans manually or sometimes automatically during an erection.

The glans 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.

<span class="mw-page-title-main">Female reproductive system</span> Reproductive system of human females

The female reproductive system is made up of the internal and external sex organs that function in the reproduction of new offspring. The human female reproductive system is immature at birth and develops to maturity at puberty to be able to produce gametes, and to carry a fetus to full term. The internal sex organs are the vagina, uterus, fallopian tubes, and ovaries. The female reproductive tract includes the vagina, uterus, and fallopian tubes and is prone to infections. The vagina allows for sexual intercourse and childbirth, and is connected to the uterus at the cervix. The uterus or womb accommodates the embryo, which develops into the fetus. The uterus also produces secretions, which help the transit of sperm to the fallopian tubes, where sperm fertilize ova produced by the ovaries. The external sex organs are also known as the genitals and these are the organs of the vulva including the labia, clitoris, and vaginal opening.

<span class="mw-page-title-main">Paramesonephric duct</span> Paired ducts in the embryo in the primitive urogenital structures

The paramesonephric ducts are paired ducts of the embryo in the female reproductive system that run down the lateral sides of the genital ridge and terminate at the sinus tubercle in the primitive urogenital sinus. In the female, they will develop to form the fallopian tubes, uterus, cervix, and the upper one-third of the vagina.

The development of the urinary system begins during prenatal development, and relates to the development of the urogenital system – both the organs of the urinary system and the sex organs of the reproductive system. The development continues as a part of sexual differentiation.

<span class="mw-page-title-main">Male reproductive system</span> Reproductive system of the human male

The male reproductive system consists of a number of sex organs that play a role in the process of human reproduction. These organs are located on the outside of the body, and within the pelvis.

A pseudo-penis is any structure found on an animal that, while superficially appearing to be a penis, is derived from a different developmental path.

<span class="mw-page-title-main">Corpus cavernosum of clitoris</span> One of a pair of regions in the clitoris that contain the blood during erection

The corpus cavernosum of clitoris is one of a pair of sponge-like regions of erectile tissue of the clitoris. It is made of a sponge-like tissue that fills with blood during erection. This is homologous to the corpus cavernosum penis. The term corpora cavernosa literally means "cave-like bodies".

<span class="mw-page-title-main">Sexual differentiation in humans</span> Process of development of sex differences in humans

Sexual differentiation in humans is the process of development of sex differences in humans. It is defined as the development of phenotypic structures consequent to the action of hormones produced following gonadal determination. Sexual differentiation includes development of different genitalia and the internal genital tracts and body hair plays a role in sex identification.

<span class="mw-page-title-main">Human penis</span> Human male external reproductive organ

In human anatomy, the penis is an external male sex organ that additionally serves as the urinary duct. The main parts are the root, body, the epithelium of the penis including the shaft skin, and the foreskin covering the glans. The body of the penis is made up of three columns of tissue: two corpora cavernosa on the dorsal side and corpus spongiosum between them on the ventral side. The human male urethra passes through the prostate gland, where it is joined by the ejaculatory duct, and then through the penis. The urethra traverses the corpus spongiosum, and its opening, the meatus, lies on the tip of the glans. It is a passage both for urination and ejaculation of semen.

The development of the reproductive system is the part of embryonic growth that results in the sex organs and contributes to sexual differentiation. Due to its large overlap with development of the urinary system, the two systems are typically described together as the genitourinary system.

<span class="mw-page-title-main">Corona of glans penis</span> Flare above the sulcus of the human penis

The corona of glans penis or penis crown refers to the rounded projecting border or flare that forms at the base of the glans in human males. The corona overhangs a mucosal surface, known as the neck of the penis, which separates the shaft and the glans. The deep retro-glandular coronal sulcus forms between the corona and the neck of the penis. The two sides of the corona merge on the ventral midline forming the septum glandis. The circumference of the corona is richly innervated and is described as a highly erogenous area of the glans.

<span class="mw-page-title-main">Primordial phallus</span>

In embryology, the primordial phallus refers to the clitoris of a female or the penis in the male, particularly during embryonic development of the urinary and reproductive organs, before sexual differentiation is evident. This is also the case for the immature male analog, the immature glans penis.

The reproductive system of an organism, also known as the genital system, is the biological system made up of all the anatomical organs involved in sexual reproduction. Many non-living substances such as fluids, hormones, and pheromones are also important accessories to the reproductive system. Unlike most organ systems, the sexes of differentiated species often have significant differences. These differences allow for a combination of genetic material between two individuals, which allows for the possibility of greater genetic fitness of the offspring.

<span class="mw-page-title-main">Diphallia</span> Genital medical condition

Diphallia, penile duplication (PD), diphallic terata, or diphallasparatus is an extremely rare developmental abnormality in which a male is born with two penises. The first reported case was by Johannes Jacob Wecker in 1609. Its occurrence is 1 in 5.5 million boys in the United States.

<span class="mw-page-title-main">Foreskin</span> Retractable fold of skin which covers and protects the glans of the penis

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 glans by an elastic band of tissue, known as the frenulum. The outer skin of the foreskin meets with the inner preputial mucosa at the area of the mucocutaneous junction. The foreskin is mobile, fairly stretchable and sustains the glans in a moist environment. Except for humans, a similar structure known as a penile sheath appears in the male sexual organs of all primates and the vast majority of mammals.

<span class="mw-page-title-main">Septum glandis</span> Part of the human glans penis

The septum glandis, also septum of the glans, refers to the fibrous partition of the ventral aspect of the glans penis that separates the two glans wings in the ventral midline. The septum extends from the urethral meatus through the glanular urethra and ends in the tunica albuginea of the human penis. Externally it is attached to the frenulum which extends lower on the neck of the penis.

<span class="mw-page-title-main">Clitorophallus</span> A term that is increasingly used amongst discussions about intersex and transsexual genitalia

Clitorophallus is a term used to refer to the penis or clitoris. It is typically used when the clitorophallus is of a size where it is not clear as to whether it is a penis or a clitoris. Often it is a matter of size that leads people to differentiate it as a penis or a clitoris, though placement of the urethral meatus may also play a part.

References

  1. Netter, Frank H.; Cochard, Larry R. (2002). Netter's Atlas of human embryology. Teterboro, N.J: Icon Learning Systems. p. 159. ISBN   0-914168-99-1.
  2. Skinner, Michael K. (2018). Encyclopedia of Reproduction: Volume 1. Elsevier Science. p. 445. ISBN   978-0-12815-145-7.
  3. Prum, Richard O. (2023). Performance All the Way Down: Genes, Development, and Sexual Difference. University of Chicago Press. p. 219. ISBN   978-0-22682-978-4.
  4. Netter, Frank (2022). Netter Atlas of Human Anatomy: Classic Regional Approach - Ebook. Elsevier Health Sciences. p. 194. ISBN   978-0-32379-375-9 . Retrieved October 9, 2023.
  5. The University of North Carolina at Chapel Hill - Embryo images nr 024
  6. Joseph, Diya B.; Vezina, Chad M. (2018), "Male Reproductive Tract: Development Overview", Encyclopedia of Reproduction, Elsevier, pp. 248–255, doi:10.1016/B978-0-12-801238-3.64366-0, ISBN   9780128151457 , retrieved 2023-01-04
  7. Baskin, Laurence; Shen, Joel; Sinclair, Adriane; Cao, Mei; Liu, Xin; Liu, Ge; Isaacson, Dylan; Overland, Maya; Li, Yi; Cunha, Gerald R. (2018). "Development of the human penis and clitoris". Differentiation; Research in Biological Diversity. 103: 74–85. doi:10.1016/j.diff.2018.08.001. ISSN   1432-0436. PMC   6234061 . PMID   30249413.