The urogenital system is derived from intermediate mesoderm Mesoderm The middle germ layer of an embryo derived from three paired mesenchymal aggregates along the neural tube. Gastrulation and Neurulation. The intermediate mesoderm Mesoderm The middle germ layer of an embryo derived from three paired mesenchymal aggregates along the neural tube. Gastrulation and Neurulation differentiates into nephrogenic cords (which will go on to form the urinary system) and an adjacent area known as the gonadal ridge (which will go on to form the gonads Gonads The gamete-producing glands, ovary or testis. Hormones: Overview and Types). The nephrogenic cords elongate in a caudal direction and sequentially develop 3 different structures: the pronephros (rudimentary and nonfunctional), the mesonephros (forms the primitive urinary system), and the metanephros (forms the permanent kidney). Concurrently, the genital system develops in close association with the urinary system. Genital development depends on chromosomal sex Sex The totality of characteristics of reproductive structure, functions, phenotype, and genotype, differentiating the male from the female organism. Gender Dysphoria, which determines whether the primitive gonads Gonads The gamete-producing glands, ovary or testis. Hormones: Overview and Types differentiate into testes Testes Gonadal Hormones or ovaries Ovaries Ovaries are the paired gonads of the female reproductive system that contain haploid gametes known as oocytes. The ovaries are located intraperitoneally in the pelvis, just posterior to the broad ligament, and are connected to the pelvic sidewall and to the uterus by ligaments. These organs function to secrete hormones (estrogen and progesterone) and to produce the female germ cells (oocytes). Ovaries: Anatomy. The gonads Gonads The gamete-producing glands, ovary or testis. Hormones: Overview and Types then secrete certain hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types, which direct further development of both the internal and external genital structures.
Last updated: 22 Jun, 2022
Develops around week 2 of embryonic life:
Layers:
Layers of the trilaminar disc Trilaminar disc Gastrulation and Neurulation
Image by Lecturio.Cross-sectional view of the early embryo Embryo The entity of a developing mammal, generally from the cleavage of a zygote to the end of embryonic differentiation of basic structures. For the human embryo, this represents the first two months of intrauterine development preceding the stages of the fetus. Fertilization and First Week
Image by Lecturio.The kidney develops from embryonic mesoderm Mesoderm The middle germ layer of an embryo derived from three paired mesenchymal aggregates along the neural tube. Gastrulation and Neurulation in 3 successive forms from the nephrogenic cords as the cords elongate in a cranial-to-caudal direction.
Developmental location of the pronephros, mesonephros, and metanephros in the developing embryo Embryo The entity of a developing mammal, generally from the cleavage of a zygote to the end of embryonic differentiation of basic structures. For the human embryo, this represents the first two months of intrauterine development preceding the stages of the fetus. Fertilization and First Week
Image by Lecturio.Graphical summary of the mesonephros:
Note that the nephrogenic cords (primary nephric ducts) elongate and join with the
cloaca
Cloaca
A dilated cavity extended caudally from the hindgut. In adult birds, reptiles, amphibians, and many fishes but few mammals, cloaca is a common chamber into which the digestive, urinary and reproductive tracts discharge their contents. In most mammals, cloaca gives rise to large intestine; urinary bladder; and genitalia.
Development of the Abdominal Organs. Mesonephric tubules grow in a stepladder-like pattern and function as a primitive urinary system, while the definitive kidney develops from the metanephros further down in the growing
pelvis
Pelvis
The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities.
Pelvis: Anatomy.
The permanent kidney is formed from the metanephros.
Graphical summary of the developing kidney:
The ureteric bud grows off of the
mesonephric duct
Mesonephric duct
A pair of excretory ducts of the middle kidneys of an embryo, also called mesonephric ducts. In higher vertebrates, wolffian ducts persist in the male forming vas deferens, but atrophy into vestigial structures in the female.
Kidneys: Anatomy and into a collection of intermediate
mesoderm
Mesoderm
The middle germ layer of an embryo derived from three paired mesenchymal aggregates along the neural tube.
Gastrulation and Neurulation cells known as the
metanephric blastema
Metanephric blastema
Wilms Tumor. Together, these are known as the mesonephros, which develops into the kidney. The mesonephric tubules regress. In males, the
mesonephric duct
Mesonephric duct
A pair of excretory ducts of the middle kidneys of an embryo, also called mesonephric ducts. In higher vertebrates, wolffian ducts persist in the male forming vas deferens, but atrophy into vestigial structures in the female.
Kidneys: Anatomy persists in the ejaculatory system.
Growth, elongation Elongation Polymerase Chain Reaction (PCR), and division of the ureteric buds, which form the ureters Ureters One of a pair of thick-walled tubes that transports urine from the kidney pelvis to the urinary bladder. Urinary Tract: Anatomy, the renal pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy, the major and minor calyces Minor calyces Recesses of the kidney pelvis which divides into two wide, cup-shaped major renal calices, with each major calyx subdivided into 7 to 14 minor calices. Urine empties into a minor calyx from collecting tubules, then passes through the major calyx, renal pelvis, and ureter to enter the urinary bladder. Kidneys: Anatomy, and the collecting tubule
Image by Lecturio.Ascent of the kidneys Kidneys The kidneys are a pair of bean-shaped organs located retroperitoneally against the posterior wall of the abdomen on either side of the spine. As part of the urinary tract, the kidneys are responsible for blood filtration and excretion of water-soluble waste in the urine. Kidneys: Anatomy and corresponding change in vascular supply
Image by Lecturio.Between the 4th and 7th weeks of development, the cloaca Cloaca A dilated cavity extended caudally from the hindgut. In adult birds, reptiles, amphibians, and many fishes but few mammals, cloaca is a common chamber into which the digestive, urinary and reproductive tracts discharge their contents. In most mammals, cloaca gives rise to large intestine; urinary bladder; and genitalia. Development of the Abdominal Organs divides into:
Sex differentiation
Sex differentiation
The process in developing sex- or gender-specific tissue, organ, or function after sex determination processes have set the sex of the gonads. Major areas of sex differentiation occur in the reproductive tract (genitalia) and the brain.
Sex Determination from the mesonephric (wolffian) and paramesonephric (mĂĽllerian) ducts:
In females, the mesonephric ducts regress while the paramesonephric ducts persist. The paramesonephric ducts remain open to the intraembryonic coelom (the eventual
peritoneal cavity
Peritoneal Cavity
The space enclosed by the peritoneum. It is divided into two portions, the greater sac and the lesser sac or omental bursa, which lies behind the stomach. The two sacs are connected by the foramen of winslow, or epiploic foramen.
Peritoneum: Anatomy) near the
gonads
Gonads
The gamete-producing glands, ovary or testis.
Hormones: Overview and Types, and the inferior/medial ends fuse into a common body in the midline, forming the
uterus
Uterus
The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The uterus has a thick wall made of smooth muscle (the myometrium) and an inner mucosal layer (the endometrium). The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina.
Uterus, Cervix, and Fallopian Tubes: Anatomy and upper
vagina
Vagina
The vagina is the female genital canal, extending from the vulva externally to the cervix uteri internally. The structures have sexual, reproductive, and urinary functions and a rich blood supply, mainly arising from the internal iliac artery.
Vagina, Vulva, and Pelvic Floor: Anatomy.
In males, the mesonephric ducts are closely associated with the
gonads
Gonads
The gamete-producing glands, ovary or testis.
Hormones: Overview and Types; they enter the
urogenital sinus
Urogenital Sinus
Congenital Malformations of the Female Reproductive System separately on each side becoming parts of the ejaculatory system, while the
urogenital sinus
Urogenital Sinus
Congenital Malformations of the Female Reproductive System becomes the
bladder
Bladder
A musculomembranous sac along the urinary tract. Urine flows from the kidneys into the bladder via the ureters, and is held there until urination.
Pyelonephritis and Perinephric Abscess and
prostate
Prostate
The prostate is a gland in the male reproductive system. The gland surrounds the bladder neck and a portion of the urethra. The prostate is an exocrine gland that produces a weakly acidic secretion, which accounts for roughly 20% of the seminal fluid.
.
Migration of the
primordial germ cells
Primordial germ cells
Gametogenesis around 5 weeks:
These
germ cells
Germ Cells
The reproductive cells in multicellular organisms at various stages during gametogenesis.
Gametogenesis begin as
epiblast
Epiblast
Embryoblast and Trophoblast Development cells and start developing within the
yolk sac
Yolk Sac
The first of four extra-embryonic membranes to form during embryogenesis. In reptiles and birds, it arises from endoderm and mesoderm to incorporate the egg yolk into the digestive tract for nourishing the embryo. In placental mammals, its nutritional function is vestigial; however, it is the source of intestinal mucosa; blood cells; and germ cells. It is sometimes called the vitelline sac, which should not be confused with the vitelline membrane of the egg.
Embryoblast and Trophoblast Development. The cells then migrate down the
allantois
Allantois
An extra-embryonic membranous sac derived from the yolk sac of reptiles; birds; and mammals. It lies between two other extra-embryonic membranes, the amnion and the chorion. The allantois serves to store urinary wastes and mediate exchange of gas and nutrients for the developing embryo.
Development of the Abdominal Organs, along the dorsal
mesentery
Mesentery
A layer of the peritoneum which attaches the abdominal viscera to the abdominal wall and conveys their blood vessels and nerves.
Peritoneum: Anatomy of the
hindgut
Hindgut
Development of the Abdominal Organs, and then invade the gonadal ridges, which are beginning to form the early
gonads
Gonads
The gamete-producing glands, ovary or testis.
Hormones: Overview and Types.
Formation of primitive
sex
Sex
The totality of characteristics of reproductive structure, functions, phenotype, and genotype, differentiating the male from the female organism.
Gender Dysphoria cords:
At around 6 weeks, the mesothelium of the
gonads
Gonads
The gamete-producing glands, ovary or testis.
Hormones: Overview and Types invades underlying
mesoderm
Mesoderm
The middle germ layer of an embryo derived from three paired mesenchymal aggregates along the neural tube.
Gastrulation and Neurulation, forming the primitive
sex
Sex
The totality of characteristics of reproductive structure, functions, phenotype, and genotype, differentiating the male from the female organism.
Gender Dysphoria cords. Paramesonephric ducts develop alongside the mesonephric ducts. At this stage, the mesonephric ducts are functioning as part of the primitive urinary system (mesonephros); however, as the definitive kidney (from the metanephros) takes over, the mesonephric ducts will begin differentiating into male genital structures in males or regress in females.
Structures of the male reproductive system
Image: “Male Reproductive System” by OpenStax College. License: CC BY 4.0, cropped by Lecturio.Anatomy of the testis
Image: “Anatomy of the testis” by OpenStax College. License: CC BY 4.0Male development
Image by Lecturio.Step 1: Fusion of the paramesonephric ducts
Step 2: Connection of the fused paramesonephric ducts to the urogenital sinus Urogenital Sinus Congenital Malformations of the Female Reproductive System
Development of the uterus Uterus The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The uterus has a thick wall made of smooth muscle (the myometrium) and an inner mucosal layer (the endometrium). The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Uterus, Cervix, and Fallopian Tubes: Anatomy, cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy, and vagina Vagina The vagina is the female genital canal, extending from the vulva externally to the cervix uteri internally. The structures have sexual, reproductive, and urinary functions and a rich blood supply, mainly arising from the internal iliac artery. Vagina, Vulva, and Pelvic Floor: Anatomy (anterior view)
Image by Lecturio.Development of the uterus Uterus The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The uterus has a thick wall made of smooth muscle (the myometrium) and an inner mucosal layer (the endometrium). The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Uterus, Cervix, and Fallopian Tubes: Anatomy, cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy, and vagina Vagina The vagina is the female genital canal, extending from the vulva externally to the cervix uteri internally. The structures have sexual, reproductive, and urinary functions and a rich blood supply, mainly arising from the internal iliac artery. Vagina, Vulva, and Pelvic Floor: Anatomy (lateral view)
Image by Lecturio.Undifferentiated structure | In the presence of testosterone Testosterone A potent androgenic steroid and major product secreted by the leydig cells of the testis. Its production is stimulated by luteinizing hormone from the pituitary gland. In turn, testosterone exerts feedback control of the pituitary LH and FSH secretion. Depending on the tissues, testosterone can be further converted to dihydrotestosterone or estradiol. Androgens and Antiandrogens | Estrogen Estrogen Compounds that interact with estrogen receptors in target tissues to bring about the effects similar to those of estradiol. Estrogens stimulate the female reproductive organs, and the development of secondary female sex characteristics. Estrogenic chemicals include natural, synthetic, steroidal, or non-steroidal compounds. Ovaries: Anatomy/lack of testosterone Testosterone A potent androgenic steroid and major product secreted by the leydig cells of the testis. Its production is stimulated by luteinizing hormone from the pituitary gland. In turn, testosterone exerts feedback control of the pituitary LH and FSH secretion. Depending on the tissues, testosterone can be further converted to dihydrotestosterone or estradiol. Androgens and Antiandrogens |
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Urogenital sinus Urogenital Sinus Congenital Malformations of the Female Reproductive System |
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Genital tubercle (forms erectile tissue) |
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Genital folds |
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Labia minora Labia minora Vagina, Vulva, and Pelvic Floor: Anatomy |
Genital swelling Swelling Inflammation | Scrotum Scrotum A cutaneous pouch of skin containing the testicles and spermatic cords. Testicles: Anatomy | Labia majora Labia majora Vagina, Vulva, and Pelvic Floor: Anatomy |
Phenotypic differentiation of the external genitalia in male and female embryos:
Both male and female external genitalia develop from the same starting structures but diverge as they are exposed to different levels of
androgens
Androgens
Androgens are naturally occurring steroid hormones responsible for development and maintenance of the male sex characteristics, including penile, scrotal, and clitoral growth, development of sexual hair, deepening of the voice, and musculoskeletal growth.
Androgens and Antiandrogens and estrogens.
Illustration showing types of congenital malformations Congenital malformations Congenital malformations or teratogenic birth defects are developmental disorders that arise before birth during the embryonic or fetal period. The rate of incidence for children born alive is approximately 3%. Teratogenic Birth Defects of the uterus Uterus The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The uterus has a thick wall made of smooth muscle (the myometrium) and an inner mucosal layer (the endometrium). The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Uterus, Cervix, and Fallopian Tubes: Anatomy
Image by Lecturio. License: CC BY-NC-SA 4.0Normal parous hymen Hymen A thin fold of mucous membrane situated at the orifice of the vagina. Vagina, Vulva, and Pelvic Floor: Anatomy compared to common hymen Hymen A thin fold of mucous membrane situated at the orifice of the vagina. Vagina, Vulva, and Pelvic Floor: Anatomy malformations, including microperforate, septate, cribriform, and imperforate hymens
Image by Lecturio. License: CC BY-NC-SA 4.0Disorders of sexual development (DSDs) are a group of conditions characterized by atypical sexual development in an individual, which may involve abnormalities in the structure and/or function of the internal reproductive organs and/or external genitalia.