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Development Of The Reproductive System
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 The reproductive organs develop from the intermediate mesoderm and are preceded by more primitive structures that are superseded before birth. These embryonic structures are the mesonephric ducts (also known as ''Wolffian ducts'') and the paramesonephric ducts, (also known as ''Müllerian ducts''). The mesonephric duct gives rise to the male seminal vesicles, epididymides and vasa deferentia. The paramesonephric duct gives rise to the female fallopian tubes, uterus, cervix, and upper part of the vagina. Mesonephric ducts The mesonephric duct originates from a part of the pronephric duct. Origin In the outer part of the intermediate mesoderm, immediately under the ectoderm, in the re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prenatal Development
Prenatal development () involves the development of the embryo and of the fetus during a viviparous animal's gestation. Prenatal development starts with fertilization, in the germinal stage of embryonic development, and continues in fetal development until birth. The term "prenate" is used to describe an unborn offspring at any stage of gestation. In human pregnancy, prenatal development is also called antenatal development. The development of the human embryo follows fertilization, and continues as fetal development. By the end of the tenth week of gestational age, the embryo has acquired its basic form and is referred to as a fetus. The next period is that of fetal development where many organs become fully developed. This fetal period is described both topically (by organ) and chronologically (by time) with major occurrences being listed by gestational age. The very early stages of embryonic development are the same in all mammals, but later stages of development, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cervical Segment
The spinal cord is a long, thin, tubular structure made up of nervous tissue that extends from the medulla oblongata in the lower brainstem to the lumbar region of the vertebral column (backbone) of vertebrate animals. The center of the spinal cord is hollow and contains a structure called the central canal, which contains cerebrospinal fluid. The spinal cord is also covered by meninges and enclosed by the neural arches. Together, the brain and spinal cord make up the central nervous system. In humans, the spinal cord is a continuation of the brainstem and anatomically begins at the occipital bone, passing out of the foramen magnum and then enters the spinal canal at the beginning of the cervical vertebrae. The spinal cord extends down to between the first and second lumbar vertebrae, where it tapers to become the cauda equina. The enclosing bony vertebral column protects the relatively shorter spinal cord. It is around long in adult men and around long in adult women. The d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spermatic Cord
The spermatic cord is the cord-like structure in males formed by the vas deferens (''ductus deferens'') and surrounding tissue that runs from the deep inguinal ring down to each testicle. Its serosal covering, the tunica vaginalis, is an extension of the peritoneum that passes through the transversalis fascia. Each testicle develops in the lower thoracic and upper lumbar region and migrates into the scrotum. During its descent it carries along with it the vas deferens, its vessels, nerves etc. There is one on each side. Structure The spermatic cord is ensheathed in three layers of tissue: * '' external spermatic fascia'', an extension of the innominate fascia that overlies the aponeurosis of the external oblique muscle. * '' cremasteric muscle and fascia'', formed from a continuation of the internal oblique muscle and its fascia. * '' internal spermatic fascia'', continuous with the transversalis fascia. The normal diameter of the spermatic cord is about 16 mm (range 11 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paradidymis
The term paradidymis (: paradidymides; organ of Giraldés) is applied to a small collection of convoluted tubules, situated in front of the lower part of the spermatic cord, above the head of the epididymis. These tubes are lined with columnar ciliated epithelium, and probably represent the remains of a part of the Wolffian body, like the epididymis, but are functionless and vestigial. The Wolffian body operates as a kidney (mesonephros The mesonephros () is one of three excretory system, excretory organs that develop in vertebrates. It serves as the main excretory organ of aquatic vertebrates and as a temporary kidney in reptiles, birds, and mammals. The mesonephros is included ...) in fishes and amphibians, but the corresponding tissue is co-opted to form parts of the male reproductive system in other classes of vertebrate. The paradidymis represents a remnant of an unused, atrophied part of the Wolffian body. The paradidymis is homologous to the female paroophoron, as th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ductuli Aberrantes
Ductuli aberrantes are two long narrow tubes, the ductulus aberrans inferior and the ductulus aberrans superior. The ductulus aberrant inferior (vas aberrans of Haller), is occasionally found connected with the lower part of the canal of the epididymis, or with the commencement of the vas deferens. Its length varies from 3.5 to 35 cm. , and it may become dilated toward its extremity; more commonly, it retains the same diameter throughout. Its structure is similar to that of the ductus deferens. Occasionally, it is found unconnected with the epididymis. A second tube, the ductulus aberrans superior, occurs in the head of the epididymis; it is connected with the rete testis The rete testis ( ; : retia testes) is an anastomosis, anastomosing network of delicate tubules located in the hilum of the testicle (mediastinum testis) that carries spermatozoon, sperm from the seminiferous tubules to the efferent ducts. It is t .... References {{Authority control Mammal male rep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Posterior (anatomy)
Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek language, Greek roots, describe something in its standard anatomical position. This position provides a definition of what is at the front ("anterior"), behind ("posterior") and so on. As part of defining and describing terms, the body is described through the use of anatomical planes and anatomical axes, axes. The meaning of terms that are used can change depending on whether a vertebrate is a biped or a quadruped, due to the difference in the neuraxis, or if an invertebrate is a non-bilaterian. A non-bilaterian has no anterior or posterior surface for example but can still have a descriptor used such as proximal or distal in relation to a body part that is nearest to, or furthest from its middle. International organisations have determined vocabularies that are often used as standards for subdisciplines of anatomy. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Testicle
A testicle or testis ( testes) is the gonad in all male bilaterians, including humans, and is Homology (biology), homologous to the ovary in females. Its primary functions are the production of sperm and the secretion of Androgen, androgens, primarily testosterone. The release of testosterone is regulated by luteinizing hormone (LH) from the anterior pituitary gland. Sperm production is controlled by follicle-stimulating hormone (FSH) from the anterior pituitary gland and by testosterone produced within the gonads. Structure Appearance Males have two testicles of similar size contained within the scrotum, which is an extension of the abdominal wall. Scrotal asymmetry, in which one testicle extends farther down into the scrotum than the other, is common. This is because of the differences in the vasculature's anatomy. For 85% of men, the right testis hangs lower than the left one. Measurement and volume The volume of the testicle can be estimated by palpating it and compari ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seminal Vesicle
The seminal vesicles (also called vesicular glands or seminal glands) are a pair of convoluted tubular accessory glands that lie behind the urinary bladder of male mammals. They secrete fluid that largely composes the semen. The vesicles are 5–10 cm in size, 3–5 cm in diameter, and are located between the bladder and the rectum. They have multiple outpouchings, which contain secretory glands, which join together with the vasa deferentia at the ejaculatory ducts. They receive blood from the vesiculodeferential artery, and drain into the vesiculodeferential veins. The glands are lined with column-shaped and cuboidal cells. The vesicles are present in many groups of mammals, but not marsupials, monotremes or carnivores. Inflammation of the seminal vesicles is called seminal vesiculitis and most often is due to bacterial infection as a result of a sexually transmitted infection or following a surgical procedure. Seminal vesiculitis can cause pain in the lower abdo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ejaculatory Duct
The ejaculatory ducts (''ductus ejaculatorii'') are paired structures in the male reproductive system. Each ejaculatory duct is formed by the union of the vas deferens with the Excretory duct of seminal gland, duct of the seminal vesicle. They pass through the prostate, and open into the urethra above the seminal colliculus. During ejaculation, semen passes through the prostate gland, enters the urethra and exits the body via the urinary meatus. Function Ejaculation Ejaculation occurs in two stages, the emission stage and the expulsion stage.Rathus, S. A., Nevid, J. S., Fichner-Rathus, L., Herold, E. S. (2010). ''Human Sexuality in a World of Diversity''. Pearsons Education Canada, Pearson Canada Inc. Toronto, ON. The emission stage involves the workings of several structures of the ejaculatory duct; contractions of the prostate gland, the seminal vesicles, the bulbourethral gland and the vas deferens push fluids into the prostatic urethra. The semen is stored here until ejacula ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pronephros
Pronephros is the most basic of the three excretory organs that develop in vertebrates, corresponding to the first stage of kidney development. It is succeeded by the mesonephros, which in fish and amphibians remains as the adult kidney. In amniotes, the mesonephros is the embryonic kidney and a more complex metanephros acts as the adult kidney. Once a more advanced kidney forms, the previous version typically degenerates by apoptosis or becomes part of the male reproductive system. The pronephros develops from the intermediate mesoderm, as do the later kidneys. It is a paired organ, consisting of a single giant nephron that processes blood filtrate produced from glomeruli or glomera- large embryonic glomeruli. The filtrate is deposited into the coelom. It then passes through thin ciliated tubules into the pronephric nephron where it is processed for solute recovery. The organ is active in adult forms of some primitive fish, like lampreys or hagfish. It is present at the embry ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cloaca (embryology)
The cloaca (: cloacae) is a structure in the development of the urinary and reproductive organs. The hind-gut is at first prolonged backward into the body-stalk as the tube of the allantois; but, with the growth and flexure of the tail-end of the embryo, the body-stalk, with its contained allantoic tube, is carried forward to the ventral aspect of the body, and consequently a bend is formed at the junction of the hind-gut and allantois. This bend becomes dilated into a pouch, which constitutes the endodermal cloaca; into its dorsal part the hind-gut opens, and from its ventral part the allantois passes forward. At a later stage, the Wolffian duct and Müllerian duct open into its ventral portion. The cloaca is, for a time, shut off from the anterior by the cloacal membrane, formed by the apposition of the ectoderm and endoderm, and reaching, at first, as far forward as the future umbilicus. Behind the umbilicus, however, the mesoderm subsequently extends to form t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caudally
Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position provides a definition of what is at the front ("anterior"), behind ("posterior") and so on. As part of defining and describing terms, the body is described through the use of anatomical planes and axes. The meaning of terms that are used can change depending on whether a vertebrate is a biped or a quadruped, due to the difference in the neuraxis, or if an invertebrate is a non-bilaterian. A non-bilaterian has no anterior or posterior surface for example but can still have a descriptor used such as proximal or distal in relation to a body part that is nearest to, or furthest from its middle. International organisations have determined vocabularies that are often used as standards for subdisciplines of anatomy. For example, '' Terminologia A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
