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Cloaca (embryology)
The cloaca 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 the lower part of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endoderm
Endoderm is the innermost of the three primary germ layers in the very early embryo. The other two layers are the ectoderm (outside layer) and mesoderm (middle layer). Cells migrating inward along the archenteron form the inner layer of the gastrula, which develops into the endoderm. The endoderm consists at first of flattened cells, which subsequently become columnar. It forms the epithelial lining of multiple systems. In plant biology, endoderm corresponds to the innermost part of the cortex ( bark) in young shoots and young roots often consisting of a single cell layer. As the plant becomes older, more endoderm will lignify. Production The following chart shows the tissues produced by the endoderm. The embryonic endoderm develops into the interior linings of two tubes in the body, the digestive and respiratory tube. Liver and pancreas cells are believed to derive from a common precursor. In humans, the endoderm can differentiate into distinguishable organs after 5 week ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ectoderm
The ectoderm is one of the three primary germ layers formed in early embryonic development. It is the outermost layer, and is superficial to the mesoderm (the middle layer) and endoderm (the innermost layer). It emerges and originates from the outer layer of germ cells. The word ectoderm comes from the Greek ''ektos'' meaning "outside", and ''derma'' meaning "skin".Gilbert, Scott F. Developmental Biology. 9th ed. Sunderland, MA: Sinauer Associates, 2010: 333-370. Print. Generally speaking, the ectoderm differentiates to form epithelial and neural tissues (spinal cord, peripheral nerves and brain). This includes the skin, linings of the mouth, anus, nostrils, sweat glands, hair and nails, and tooth enamel. Other types of epithelium are derived from the endoderm. In vertebrate embryos, the ectoderm can be divided into two parts: the dorsal surface ectoderm also known as the external ectoderm, and the neural plate, which invaginates to form the neural tube and neural crest. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Urinary Tract
The urinary system, also known as the urinary tract or renal system, consists of the kidneys, ureters, bladder, and the urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and blood pressure, control levels of electrolytes and metabolites, and regulate blood pH. The urinary tract is the body's drainage system for the eventual removal of urine. The kidneys have an extensive blood supply via the renal arteries which leave the kidneys via the renal vein. Each kidney consists of functional units called nephrons. Following filtration of blood and further processing, wastes (in the form of urine) exit the kidney via the ureters, tubes made of smooth muscle fibres that propel urine towards the urinary bladder, where it is stored and subsequently expelled from the body by urination (voiding). The female and male urinary system are very similar, differing only in the length of the urethra. Urine is formed in the kidneys through a filtrati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vagina
In mammals, the vagina is the elastic, muscular part of the female genital tract. In humans, it extends from the vestibule to the cervix. The outer vaginal opening is normally partly covered by a thin layer of mucosal tissue called the hymen. At the deep end, the cervix (neck of the uterus) bulges into the vagina. The vagina allows for sexual intercourse and birth. It also channels menstrual flow, which occurs in humans and closely related primates as part of the menstrual cycle. Although research on the vagina is especially lacking for different animals, its location, structure and size are documented as varying among species. Female mammals usually have two external openings in the vulva; these are the urethral opening for the urinary tract and the vaginal opening for the genital tract. This is different from male mammals, who usually have a single urethral opening for both urination and reproduction. The vaginal opening is much larger than the nearby urethral opening, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rectum
The rectum is the final straight portion of the large intestine in humans and some other mammals, and the Gastrointestinal tract, gut in others. The adult human rectum is about long, and begins at the rectosigmoid junction (the end of the sigmoid colon) at the level of the third sacral vertebra or the sacral promontory depending upon what definition is used. Its diameter is similar to that of the sigmoid colon at its commencement, but it is dilated near its termination, forming the rectal ampulla. It terminates at the level of the anorectal ring (the level of the puborectalis sling) or the dentate line, again depending upon which definition is used. In humans, the rectum is followed by the anal canal which is about long, before the gastrointestinal tract terminates at the anal verge. The word rectum comes from the Latin ''Wikt:rectum, rectum Wikt:intestinum, intestinum'', meaning ''straight intestine''. Structure The rectum is a part of the lower gastrointestinal tract ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Persistent Cloaca
A persistent cloaca is a symptom of a complex anorectal congenital disorder, in which the rectum, vagina, and urinary tract meet and fuse, creating a cloaca, a single common channel. Signs and symptoms Cloacas appear in a wide spectrum of variation in females born with the malformation. The single orifice, called a common channel, may occur varying in length from 1 to 10 cm. The length of the common channel can be used to judge prognostic outcomes and technical challenges during surgical repair. A common channel less than 3 cm in length usually has good sphincter muscles and a well-developed sacrum. Diagnosis Diagnosis of a female with cloaca should be suspected in a female born with an imperforate anus and small looking genitalia. The diagnosis can be made clinically. Failure to identify a cloaca as being present in a newborn may be dangerous, as more than 90% have associated urological problems. The goal for treatment of a female born with cloaca is to achieve bowel co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Birth Defect
A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can range from mild to severe. Birth defects are divided into two main types: structural disorders in which problems are seen with the shape of a body part and functional disorders in which problems exist with how a body part works. Functional disorders include metabolic and degenerative disorders. Some birth defects include both structural and functional disorders. Birth defects may result from genetic or chromosomal disorders, exposure to certain medications or chemicals, or certain infections during pregnancy. Risk factors include folate deficiency, drinking alcohol or smoking during pregnancy, poorly controlled diabetes, and a mother over the age of 35 years old. Many are believed to involve multiple factors. Birth defects may be visi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pubic Symphysis
The pubic symphysis is a secondary cartilaginous joint between the left and right superior rami of the pubis of the hip bones. It is in front of and below the urinary bladder. In males, the suspensory ligament of the penis attaches to the pubic symphysis. In females, the pubic symphysis is close to the clitoris. In most adults it can be moved roughly 2 mm and with 1 degree rotation. This increases for women at the time of childbirth. The name comes from the Greek word ''symphysis'', meaning 'growing together'. Structure The pubic symphysis is a nonsynovial amphiarthrodial joint. The width of the pubic symphysis at the front is 3–5 mm greater than its width at the back. This joint is connected by fibrocartilage and may contain a fluid-filled cavity; the center is avascular, possibly due to the nature of the compressive forces passing through this joint, which may lead to harmful vascular disease. The ends of both pubic bones are covered by a thin layer of hyaline ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abdominal Wall
In anatomy, the abdominal wall represents the boundaries of the abdominal cavity. The abdominal wall is split into the anterolateral and posterior walls. There is a common set of layers covering and forming all the walls: the deepest being the visceral peritoneum, which covers many of the abdominal organs (most of the large and small intestines, for example), and the parietal peritoneum- which covers the visceral peritoneum below it, the extraperitoneal fat, the transversalis fascia, the internal and external oblique and transversus abdominis aponeurosis, and a layer of fascia, which has different names according to what it covers (e.g., transversalis, psoas fascia). In medical vernacular, the term 'abdominal wall' most commonly refers to the layers composing the anterior abdominal wall which, in addition to the layers mentioned above, includes the three layers of muscle: the transversus abdominis (transverse abdominal muscle), the internal (obliquus internus) and the external o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Navel
The navel (clinically known as the umbilicus, commonly known as the belly button or tummy button) is a protruding, flat, or hollowed area on the abdomen at the attachment site of the umbilical cord. All placental mammals have a navel, although it is generally more conspicuous in humans. Structure The umbilicus is used to visually separate the abdomen into quadrants. The umbilicus is a prominent scar on the abdomen, with its position being relatively consistent among humans. The skin around the waist at the level of the umbilicus is supplied by the tenth thoracic spinal nerve (T10 dermatome). The umbilicus itself typically lies at a vertical level corresponding to the junction between the L3 and L4 vertebrae, with a normal variation among people between the L3 and L5 vertebrae. Parts of the adult navel include the "umbilical cord remnant" or "umbilical tip", which is the often protruding scar left by the detachment of the umbilical cord. This is located in the center of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cloacal Membrane
The cloacal membrane is the membrane that covers the embryonic cloaca during the development of the urinary and reproductive organs. It is formed by ectoderm and endoderm coming into contact with each other. As the human embryo grows and caudal folding continues, the urorectal septum divides the cloaca into a ventral urogenital sinus The urogenital sinus is a part of the human body only present in the development of the urinary and reproductive organs. It is the ventral part of the cloaca, formed after the cloaca separates from the anal canal during the fourth to seventh w ... and dorsal anorectal canal. Before the urorectal septum has an opportunity to fuse with the cloacal membrane, the membrane ruptures, exposing the urogenital sinus and dorsal anorectal canal to the exterior. Later on, an ectodermal plug, the anal membrane, forms to create the lower third of the rectum. It ruptures in the seventh week of gestation. References External links * * Diagram at unsw. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Urogenital Sinus
The urogenital sinus is a part of the human body only present in the development of the urinary and reproductive organs. It is the ventral part of the cloaca, formed after the cloaca separates from the anal canal during the fourth to seventh weeks of development. In males, the UG sinus is divided into three regions: upper, pelvic, and phallic. The upper part gives rise to the urinary bladder and the pelvic part gives rise to the prostatic and membranous parts of the urethra, the prostate and the bulbourethral gland (Cowper's). The phallic portion gives rise to the spongy (bulbar) part of the urethra and the urethral glands (Littre's). Note that the penile part of the urethra originates from urogenital fold. In females, the pelvic part of the UG sinus gives rise to the sinovaginal bulbs, structures that will eventually form the inferior two thirds of the vagina. This process begins when the lower tip of the paramesonephric ducts, the structures that will eventually form the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
