Spermatogenesis is the process by which haploid spermatozoa develop from germ cells in the seminiferous tubules of the testicle. This process starts with the mitotic division of the stem cells located close to the basement membrane of the tubules. These cells are called spermatogonial stem cells. The mitotic division of these produces two types of cells. Type A cells replenish the stem cells, and type B cells differentiate into primary spermatocytes. The primary spermatocyte divides meiotically into two secondary spermatocytes; each secondary spermatocyte divides into two equal haploid spermatids by Meiosis II. The spermatids are transformed into spermatozoa (sperm) by the process of spermiogenesis. These develop into mature spermatozoa, also known as sperm cells. Thus, the primary spermatocyte gives rise to two cells, the secondary spermatocytes, and the two secondary spermatocytes by their subdivision produce four spermatozoa and four haploid cells.
XY complete gonadal dysgenesis, also known as Swyer syndrome, is a type of defect hypogonadism in a person whose karyotype is 46,XY. Though they typically have normal vulvas, the person has underdeveloped gonads, fibrous tissue termed "streak gonads", and if left untreated, will not experience puberty. The cause is a lack or inactivation of an SRY gene which is responsible for sexual differentiation. Pregnancy is sometimes possible in Swyer syndrome with assisted reproductive technology. The phenotype is usually similar to Turner syndrome (45,X0) due to a lack of X inactivation. The typical medical treatment is hormone replacement therapy. The syndrome was named after Gerald Swyer, an endocrinologist based in London.
The paramesonephric 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 urogenital sinus. In the female, they will develop to form the fallopian tubes/oviducts, uterus, cervix, and the upper one-third of the vagina.
Persistent Müllerian duct syndrome (PMDS) is the presence of Müllerian duct derivatives in what would be considered a genetically and otherwise physically normal male animal by typical human based standards. In humans, PMDS typically is due to an autosomal recessive congenital disorder and is considered by some to be a form of pseudohermaphroditism due to the presence of Müllerian derivatives. PMDS can also present in non-human animals.
Anti-Müllerian hormone (AMH), also known as Müllerian-inhibiting hormone (MIH), is a glycoprotein hormone structurally related to inhibin and activin from the transforming growth factor beta superfamily, whose key roles are in growth differentiation and folliculogenesis. In humans, it is encoded by the AMH gene, on chromosome 19p13.3, while its receptor is encoded by the AMHR2 gene on chromosome 12.
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.
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.
The human reproductive system includes the male reproductive system, which functions to produce and deposit sperm, and the female reproductive system, which functions to produce egg cells and to protect and nourish the fetus until birth. Humans have a high level of sexual differentiation. In addition to differences in nearly every reproductive organ, there are numerous differences in typical secondary sex characteristics.
Intermediate mesoderm or intermediate mesenchyme is a narrow section of the mesoderm located between the paraxial mesoderm and the lateral plate of the developing embryo. The intermediate mesoderm develops into vital parts of the urogenital system.
Sex cords are embryonic structures which eventually will give rise (differentiate) to the adult gonads. They are formed from the genital ridges - which will develop into the gonads - in the first 2 months of gestation which depending on the sex of the embryo will give rise to male or female sex cords. These epithelial cells penetrate and invade the underlying mesenchyme to form the primitive sex cords. This occurs shortly before and during the arrival of the primordial germ cells (PGCs) to the paired genital ridges. If there is a Y chromosome present, testicular cords will develop via the Sry gene : repressing the female sex cord genes and activating the male. If there is no Y chromosome present the opposite will occur, developing ovarian cords. Prior to giving rise to sex cords, both XX and XY embryos have Müllerian ducts and Wolffian ducts. One of these structures will be repressed to induce the other to further differentiate into the external genitalia.
Gonadal dysgenesis is classified as any congenital developmental disorder of the reproductive system characterized by a progressive loss of primordial germ cells on the developing gonads of an embryo. One type of gonadal dysgenesis is the development of functionless, fibrous tissue, termed streak gonads, instead of reproductive tissue. Streak gonads are a form of aplasia, resulting in hormonal failure that manifests as sexual infantism and infertility, with no initiation of puberty and secondary sex characteristics.
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.
Pseudohermaphroditism is an outdated term for when an individual's gonads were mismatched with their internal reproductive system and/or external genitalia. The term was contrasted with "true hermaphroditism", a condition describing an individual with both female and male reproductive gonadal tissues. Associated conditions includes Persistent Müllerian duct syndrome and forms of androgen insensitivity syndrome.
Anti-Müllerian hormone receptor, also known as Müllerian Inhibiting Substance Type II Receptor, is a receptor for the anti-Müllerian hormone (AMH). Furthermore, anti-Müllerian hormone receptor type 2 is a protein in humans that is encoded by the AMHR2 gene.
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.
The development of the gonads is part of the prenatal development of the reproductive system and ultimately forms the testicles in males and the ovaries in females. The immature ova originate from cells from the dorsal endoderm of the yolk sac. Once they have reached the gonadal ridge they are called oogonia. Development proceeds and the oogonia become fully surrounded by a layer of connective tissue cells. In this way, the rudiments of the ovarian follicles are formed.
WNT4 is a secreted protein that, in humans, is encoded by the WNT4 gene, found on chromosome 1. It promotes female sex development and represses male sex development. Loss of function may have consequences, such as female to male sex reversal.
The uterus-like mass (ULM) is a tumorlike anatomical entity originally described in the ovary in 1981 and thereafter reported in several locations of the pelvis and abdominal cavity including broad ligament, greater omentum, cervix, small intestine, mesentery and conus medullaris. Basically, it is represented by a miniature uterus comprising a smooth muscle wall lined by endometrium thus outlining a uterus anatomical structure. Some of the reported cases have been associated to urinary tract and internal genitalia malformations whereas others appeared as a solitary finding. The term endomyometriosis has also been applied to this lesion.
46,XX/46,XY is either a chimeric or mosaic genetic condition characterized by the presence of some cells that express a 46,XX karyotype and some cells that express a 46,XY karyotype in a single human being. While some individuals with this condition may be classified as intersex, others may have typical male or female characteristics.
Thoracic endometriosis is a rare form of endometriosis where endometrial-like tissue is found in the lung parenchyma and/or the pleura. It can be classified as either pulmonary, or pleural, respectively. Endometriosis is characterized by the presence of tissue similar to the lining of the uterus forming abnormal growths elsewhere in the body. Usually these growths are found in the pelvis, between the rectum and the uterus, the ligaments of the pelvis, the bladder, the ovaries, and the sigmoid colon. The cause is not known. The most common symptom of thoracic endometriosis is chest pain occurring right before or during menstruation. Diagnosis is based on clinical history and examination, augmented with X-ray, CT scan, and magnetic resonance imaging of the chest. Treatment options include surgery and hormones.
