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Sinus Tubercle
Sinus tubercle (also known as sinual tubercle or Müllerian eminence) is the proliferation of endoderm induced by the paramesonephric ducts. It is located in the developing fetus between the orifices of the mesonephric ducts on the urogenital sinus. The uterovaginal primoridium, which is a fusion of the caudal ends of paramesonephric ducts, contacts the dorsal wall of the urogenital sinus and, induces the formation of the sinus tubercle. This occurs in both sexes: *In the female the mesonephric duct loses all association with the gonad and, disappears. The sinus tubercle then gives rise to the sino-vaginal bulbs and, when it later becomes solid it is referred to as the vaginal plate. It likewise gives rise to the hymen The hymen is a thin piece of mucosal tissue that surrounds or partially covers the external vaginal opening. It forms part of the vulva, or external genitalia, and is similar in structure to the vagina. In children, a common appearance of the ..., which ... [...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 wee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paramesonephric Ducts
Paramesonephric ducts (or Müllerian ducts) are paired ducts of the embryo 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, uterus, cervix, and the upper one-third of the vagina. Development The female reproductive system is composed of two embryological segments: the urogenital sinus and the paramesonephric ducts. The two are conjoined at the sinus tubercle. Paramesonephric ducts are present on the embryo of both sexes. Only in females do they develop into reproductive organs. They degenerate in males of certain species, but the adjoining mesonephric ducts develop into male reproductive organs. The sex based differences in the contributions of the paramesonephric ducts to reproductive organs is based on the presence, and degree of presence, of Anti-Müllerian hormone. During the formation of the reproductive system, the paramesonephric ducts a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesonephric Duct
The mesonephric duct (also known as the Wolffian duct, archinephric duct, Leydig's duct or nephric duct) is a paired organ that forms during the embryonic development of humans and other mammals and gives rise to male reproductive organs. Structure The mesonephric duct connects the primitive kidney, the ''mesonephros'', to the cloaca. It also serves as the primordium for male urogenital structures including the epididymis, vas deferens, and seminal vesicles. Development In both male and female the mesonephric duct develops into the trigone of urinary bladder, a part of the bladder wall, but the sexes differentiate in other ways during development of the urinary and reproductive organs. Male In a male, it develops into a system of connected organs between the efferent ducts of the testis and the prostate, namely the epididymis, the vas deferens, and the seminal vesicle. The prostate forms from the urogenital sinus and the efferent ducts form from the mesonephric tu ... [...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] |
Mesonephric Duct
The mesonephric duct (also known as the Wolffian duct, archinephric duct, Leydig's duct or nephric duct) is a paired organ that forms during the embryonic development of humans and other mammals and gives rise to male reproductive organs. Structure The mesonephric duct connects the primitive kidney, the ''mesonephros'', to the cloaca. It also serves as the primordium for male urogenital structures including the epididymis, vas deferens, and seminal vesicles. Development In both male and female the mesonephric duct develops into the trigone of urinary bladder, a part of the bladder wall, but the sexes differentiate in other ways during development of the urinary and reproductive organs. Male In a male, it develops into a system of connected organs between the efferent ducts of the testis and the prostate, namely the epididymis, the vas deferens, and the seminal vesicle. The prostate forms from the urogenital sinus and the efferent ducts form from the mesonephric tu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sino-vaginal Bulb
The sinovaginal bulb is a transitional structure in the development of female genitalia, and is one of a pair of endodermal outgrowths of the urogenital sinus, which later fuse to form the lower part of the vagina. The lower third of the vagina is derived from the urogenital sinus. The hymen The hymen is a thin piece of mucosal tissue that surrounds or partially covers the external vaginal opening. It forms part of the vulva, or external genitalia, and is similar in structure to the vagina. In children, a common appearance of the ... is formed from the same tissue as the sinovaginal bulb. References Vagina {{developmental-biology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vaginal Plate
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 openi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hymen
The hymen is a thin piece of mucosal tissue that surrounds or partially covers the external vaginal opening. It forms part of the vulva, or external genitalia, and is similar in structure to the vagina. In children, a common appearance of the hymen is crescent-shaped, although many shapes are possible. During puberty, estrogen causes the hymen to change in appearance and become very elastic. Normal variations of the post-pubertal hymen range from thin and stretchy to thick and somewhat rigid. Very rarely, it may be completely absent. The hymen can rip or tear during first penetrative intercourse, which usually results in pain and, sometimes, mild temporary bleeding or spotting. Sources differ on how common tearing or bleeding after first intercourse are. The state of the hymen is not a reliable indicator of virginity, though " virginity testing" remains a common practice in some cultures, sometimes accompanied by surgical restoration of hymen to give the appearance of virgini ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seminal Colliculus
The seminal colliculus (Latin ''colliculus seminalis''), or verumontanum, of the prostatic urethra is a landmark distal to the entrance of the ejaculatory ducts (on both sides, corresponding vas deferens and seminal vesicle feed into corresponding ejaculatory duct). ''Verumontanum'' is translated from Latin to mean 'mountain ridge', a reference to the distinctive median elevation of urothelium that characterizes the landmark on magnified views. Embryologically, it is derived from the uterovaginal primordium. The landmark is important in classification of several urethral developmental disorders. The margins of seminal colliculus are the following: * the orifices of the prostatic utricle * the slit-like openings of the ejaculatory ducts. * the openings of the prostatic ducts Posterior urethral valves The verumontanum is an important anatomic landmark for pathology in a congenital anomaly known as posterior urethral valves, in which there is a developmental obstruction of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Animal Developmental Biology
Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and go through an ontogenetic stage in which their body consists of a hollow sphere of cells, the blastula, during embryonic development. Over 1.5 million living animal species have been described—of which around 1 million are insects—but it has been estimated there are over 7 million animal species in total. Animals range in length from to . They have complex interactions with each other and their environments, forming intricate food webs. The scientific study of animals is known as zoology. Most living animal species are in Bilateria, a clade whose members have a bilaterally symmetric body plan. The Bilateria include the protostomes, containing animals such as nematodes, arthropods, flatworms, annelids and molluscs, and the deuterostomes, containing the echinoderms an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
