Penis Development

Embryology - 20 Oct 2026        Expand to Translate
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Introduction

Week 9, the indifferent stage of external genitalia.

The external male genitalia consists of the penis and scrotum containing the testis.

Mesonephric duct = Wolffian duct.

Genital Links: genital | Lecture - Medicine | Lecture - Science | Lecture Movie | Medicine - Practical | primordial germ cell | meiosis | endocrine gonad‎ | Genital Movies | genital abnormalities | Assisted Reproductive Technology | puberty | Category:Genital Female | X | X inactivation | ovary | corpus luteum | oocyte | uterus | vagina | reproductive cycles | menstrual cycle | Category:Female Male | Y | SRY | testis | spermatozoa | ductus deferens | penis | prostate | Category:Male

Historic Embryology - Genital  General: 1901 Urinogenital Tract | 1902 The Uro-Genital System | 1904 Ovary and Testis | 1912 Urinogenital Organ Development | 1914 External Genitalia | 1921 Urogenital Development | 1921 External Genital | 1942 Sex Cords | 1953 Germ Cells | Historic Embryology Papers | Historic Disclaimer Female: 1904 Ovary and Testis | 1904 Hymen | 1912 Urinogenital Organ Development | 1914 External Genitalia | 1914 Female | 1921 External Genital | 1927 Female Foetus 15 cm | 1927 Vagina | 1932 Postnatal Ovary Male: 1887-88 Testis | 1904 Ovary and Testis | 1904 Leydig Cells | 1906 Testis vascular | 1909 Prostate | 1912 Prostate | 1914 External Genitalia | 1915 Cowper’s and Bartholin’s Glands | 1920 Wolffian tubules | 1935 Prepuce | 1935 Wolffian Duct | 1942 Sex Cords | 1943 Testes Descent | Historic Embryology Papers | Historic Disclaimer

Some Recent Findings

Immunohistochemical expression analysis of the human fetal lower urogenital tract "We have studied the ontogeny of the developing human Male and Female urogenital tracts from 9 weeks (indifferent stage) to 16 weeks (advanced sex differentiation) of gestation by immunohistochemistry on mid-sagittal sections. Sixteen human fetal pelvises were serial sectioned in the sagittal plane and stained with antibodies to epithelial, muscle, nerve, proliferation and hormone receptor markers. Key findings are: (1) The corpus cavernosum in males and females extends into the glans penis and clitoris, respectively, during the ambisexual stage (9 weeks) and thus appears to be an androgen-independent event. (2) The entire human male (and female) urethra is endodermal in origin based on the presence of FOXA1, KRT 7, uroplakin, and the absence of KRT10 staining. The endoderm of the urethra interfaces with ectodermal epidermis at the site of the urethral meatus. (3) The surface epithelium of the verumontanum is endodermal in origin (FOXA1-positive) with a possible contribution of Pax2-positive epithelial cells implying additional input from the Wolffian duct epithelium. (4) Prostatic ducts arise from the endodermal (FOXA1-positive) urogenital sinus epithelium near the verumontanum. (5) Immunohistochemical staining of mid-sagittal and para-sagittal sections revealed the external anal sphincter, levator ani, bulbospongiosus muscle and the anatomic relationships between these developing skeletal muscles and organs of the Male and Female reproductive tracts." Development of the human penis and clitoris "The human penis and clitoris develop from the ambisexual genital tubercle. To compare and contrast the development of human penis and clitoris, we used macroscopic photography, optical projection tomography, light sheet microscopy, scanning electron microscopy, histology and immunohistochemistry. The human genital tubercle differentiates into a penis under the influence of androgens forming a tubular urethra that develops by canalization of the urethral plate to form a wide diamond-shaped urethral groove (opening zipper) whose edges (urethral folds) fuse in the midline (closing zipper). In contrast, in females, without the influence of androgens, the vestibular plate (homologue of the urethral plate) undergoes canalization to form a wide vestibular groove whose edges (vestibular folds) remain unfused, ultimately forming the labia minora defining the vaginal vestibule. The neurovascular anatomy is similar in both the developing human penis and clitoris and is the key to successful surgical reconstructions." Contrasting mechanisms of penile urethral formation in mouse and human "This paper addresses the developmental mechanisms of formation of the mouse and human penile urethra and the possibility that two disparate mechanisms are at play. It has been suggested that the entire penile urethra of the mouse forms via direct canalization of the endodermal urethral plate. While this mechanism surely accounts for development of the proximal portion of the mouse penile urethra, we suggest that the distal portion of the mouse penile urethra forms via a series of epithelial fusion events. Through review of the recent literature in combination with new data, it is unlikely that the entire mouse urethra is formed from the endodermal urethral plate due in part to the fact that from E14 onward the urethral plate is not present in the distal aspect of the genital tubercle. Formation of the distal portion of the mouse urethra receives substantial contribution from the preputial swellings that form the preputial-urethral groove and subsequently the preputial-urethral canal, the later of which is subdivided by a fusion event to form the distal portion of the mouse penile urethra. Examination of human penile development also reveals comparable dual morphogenetic mechanisms. However, in the case of human, direct canalization of the urethral plate occurs in the glans, while fusion events are involved in formation of the urethra within the penile shaft, a pattern exactly opposite to that of the mouse. The highest incidence of hypospadias in humans occurs at the junction of these two different developmental mechanisms. The relevance of the mouse as a model of human hypospadias is discussed." Complex epithelial remodeling underlie the fusion event in early fetal development of the human penile urethra "The opening zipper progresses from proximal to distal along the shaft of the penis and clitoris into the glans in identical fashion in both sexes. The closing zipper mechanism is active only in males and is not a single process but rather a series of layered fusion events, uniquely different from the simple fusion of two epithelial surfaces as occurs in formation of the palate and neural tube." Penile biometry on prenatal MR imaging "Mean length values, including 95% confidence intervals and percentiles, were defined. Penile length as a function of gestational age was expressed by the regression equation: outer mean length= -5.514 + 0.622 *, and total mean length= -8.865 + 1.312 * (*= gestational weeks). The correlation coefficients were statistically significant (p < .001). The comparison between outer length on MRI and US data showed no significant differences, whereas total length on MRI and US data demonstrated significant differences (p< .001)."

More recent papers

This table allows an automated computer search of the external PubMed database using the listed "Search term" text link. This search now requires a manual link as the original PubMed extension has been disabled. The displayed list of references do not reflect any editorial selection of material based on content or relevance. References also appear on this list based upon the date of the actual page viewing. References listed on the rest of the content page and the associated discussion page (listed under the publication year sub-headings) do include some editorial selection based upon both relevance and availability. More? References | Discussion Page | Journal Searches | 2019 References | 2020 References Search term: Penis Embryology | Penis Development

Older papers

These papers originally appeared in the Some Recent Findings table, but as that list grew in length have now been shuffled down to this collapsible table. See also the Discussion Page for other references listed by year and References on this current page. Modifications of erectile tissue components in the penis during the fetal period "The penile erectile tissue has a complex microscopic anatomy with important functions in the mechanism of penile erection. The knowledge of such structures is necessary for understanding the normal physiology of the adult penis. Therefore, it is important to know the changes of these penile structures during fetal development. This study aims to analyze the development of the main components of the erectile tissue, such as collagen, smooth muscle fibers and elastic system fibers, in human fetuses. We found strong correlation between the elements analyzed with fetal age, both in corpus cavernosum and corpus spongiosum. The growth rate of these elements was more intense during the second trimester (13 to 24 WPC) of gestation, both in corpus cavernosum and in corpus spongiosum. There is greater proportional amount of collagen in the corpus spongiosum than in corpus cavernosum during all fetal period. In the corpus spongiosum, there is about four times more collagen than smooth muscle fibers and elastic system fibers, during all fetal period studied. "

Movies

‎‎Male External Page | Play

‎‎Testis Page | Play

‎‎Testis Descent Page | Play

Mesonephic Duct Development

The paired mesonephic ducts (Wolffian ducts) go through a series of developmental changes to form the male internal genital tract.

Elongation

Links:

Foreskin Development

Foreskin development occurs during the second trimester.

• GA week 12 (Week 10) - ectoderm circular invagination at the glandular periphery now grows ventrally.
• GA week 13 (Week 12) - glans partially covered by the foreskin.
• GA week 16-17 (Week 14-15) - glans almost completely covered by the foreskin.
• GA week 18-19 (Week 16-17) - complete foreskin was formed.
• GA week 20 (Week 18) - entirely involves the glans.

Abnormalities

Hypospadias

ICD-11

Hypospadias Any condition of the urethra affecting males, caused by determinants arising during the antenatal period. These conditions are characterized by a malformation of the urethra and an abnormally placed urinary meatus. This condition may also present with an incomplete foreskin that forms a hood. Hypospadias, coronal - abnormally placed urinary meatus that opens in the ventral portion of the coronal sulcus. Hypospadias, glandular - abnormally placed urinary meatus that opens at the site of the frenulum. Hypospadias, penile - abnormally placed urinary meatus that opens along the shaft of the penis. Hypospadias, penoscrotal - abnormally placed urinary meatus that opens where the shaft of the penis meets the scrotum. Hypospadias, scrotal - abnormally placed urinary meatus that opens on the scrotum. Hypospadias, perineal - abnormally placed urinary meatus that opens in the perineum.

External urethral opening on the ventral surface of penis, can extend back into scrotum. Abnormality due to failure of genital fold fusion during fetal development of the male external genitalia.

Hypospadia Classification	Meatus Opening
Anterior	on inferior surface of glans penis
Coronal	in balanopenile furrow
Distal	on distal third of shaft
Penoscrotal	at base of shaft in front of scrotum
Scrotal	on scrotum or between the genital swellings
Perineal	behind scrotum or genital swellings
Links: Genital Abnormalities | Penis Development

Links: hypospadias

Epispadias

Uncommon abnormality associated with the penis, 1 in 30,000 infant males, external urethral opening on the dorsal surface of penis.

Endocrine Disruptors

Endocrine disruptors in female reproductive tract development and carcinogenesis.

References

Reviews

Cunha GR & Baskin L. (2018). Development of human male and female urogenital tracts. Differentiation , 103, 1-4. PMID: 30262219 DOI.

Articles

Liu X, Liu G, Shen J, Yue A, Isaacson D, Sinclair A, Cao M, Liaw A, Cunha GR & Baskin L. (2018). Human glans and preputial development. Differentiation , 103, 86-99. PMID: 30245194 DOI.

Isaacson D, Shen J, Overland M, Li Y, Sinclair A, Cao M, McCreedy D, Calvert M, McDevitt T, Cunha GR & Baskin L. (2018). Three-dimensional imaging of the developing human fetal urogenital-genital tract: Indifferent stage to male and female differentiation. Differentiation , 103, 14-23. PMID: 30262218 DOI.

Liu G, Liu X, Shen J, Sinclair A, Baskin L & Cunha GR. (2018). Contrasting mechanisms of penile urethral formation in mouse and human. Differentiation , 101, 46-64. PMID: 29859371 DOI.

Wisniewski H & Terry RD. (1968). Further studies on experimental neurofibrillary tangles. J. Neuropathol. Exp. Neurol. , 27, 149-50. PMID: 5690451

Genital Links: genital | Lecture - Medicine | Lecture - Science | Lecture Movie | Medicine - Practical | primordial germ cell | meiosis | endocrine gonad‎ | Genital Movies | genital abnormalities | Assisted Reproductive Technology | puberty | Category:Genital Female | X | X inactivation | ovary | corpus luteum | oocyte | uterus | vagina | reproductive cycles | menstrual cycle | Category:Female Male | Y | SRY | testis | spermatozoa | ductus deferens | penis | prostate | Category:Male

Historic Embryology - Genital  General: 1901 Urinogenital Tract | 1902 The Uro-Genital System | 1904 Ovary and Testis | 1912 Urinogenital Organ Development | 1914 External Genitalia | 1921 Urogenital Development | 1921 External Genital | 1942 Sex Cords | 1953 Germ Cells | Historic Embryology Papers | Historic Disclaimer Female: 1904 Ovary and Testis | 1904 Hymen | 1912 Urinogenital Organ Development | 1914 External Genitalia | 1914 Female | 1921 External Genital | 1927 Female Foetus 15 cm | 1927 Vagina | 1932 Postnatal Ovary Male: 1887-88 Testis | 1904 Ovary and Testis | 1904 Leydig Cells | 1906 Testis vascular | 1909 Prostate | 1912 Prostate | 1914 External Genitalia | 1915 Cowper’s and Bartholin’s Glands | 1920 Wolffian tubules | 1935 Prepuce | 1935 Wolffian Duct | 1942 Sex Cords | 1943 Testes Descent | Historic Embryology Papers | Historic Disclaimer

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Cite this page: Hill, M.A. (2026, October 20) Embryology Penis Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Penis_Development

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© Dr Mark Hill 2026, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G