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Primary Urethral Groove
The primary urethral groove or urethral groove is a temporary linear indentation on the underside (ventral side) of the male penis during embryonic development. In humans, it typically appears around 8 weeks of gestation and becomes closed into a normal male urethra by the 12th week. Clinical significance Failure of complete closure can be associated with hypospadias Hypospadias is a common variation in fetal development of the penis in which the urethra does not open from its usual location in the head of the penis. It is the second-most common birth abnormality of the male reproductive system, affecting abou .... References {{DEFAULTSORT:Urethral Groove Embryology of urogenital system Human penis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Urogenital Folds
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 urogenital or 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 The reproductive organs develop from the intermediate mesoderm and are preceded by more primitive structures that are superseded before birth.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, epididymes and vas deferens. 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 t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Urethra
The urethra (from Greek οὐρήθρα – ''ourḗthrā'') is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, the urethra connects to the urinary meatus above the vagina, whereas in marsupials, the female's urethra empties into the urogenital sinus. Females use their urethra only for urinating, but males use their urethra for both urination and ejaculation. The external urethral sphincter is a striated muscle that allows voluntary control over urination. The internal sphincter, formed by the involuntary smooth muscles lining the bladder neck and urethra, receives its nerve supply by the sympathetic division of the autonomic nervous system. The internal sphincter is present both in males and females. Structure The urethra is a fibrous and muscular tube which connects the urinary bladder to the external urethral meatus. Its length differs between the sexes, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Penis
A penis (plural ''penises'' or ''penes'' () is the primary sexual organ that male animals use to inseminate females (or hermaphrodites) during copulation. Such organs occur in many animals, both vertebrate and invertebrate, but males do not bear a penis in every animal species, and in those species in which the male does bear a so-called penis, the penises in the various species are not necessarily homologous. The term ''penis'' applies to many intromittent organs, but not to all. As an example, the intromittent organ of most cephalopoda is the hectocotylus, a specialized arm, and male spiders use their pedipalps. Even within the Vertebrata there are morphological variants with specific terminology, such as Hemipenis, hemipenes. In most species of animals in which there is an organ that might reasonably be described as a penis, it has no major function other than intromission, or at least conveying the sperm to the female, but in the Eutheria, placental mammals the peni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Male Urethra
The urethra (from Greek οὐρήθρα – ''ourḗthrā'') is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, the urethra connects to the urinary meatus above the vagina, whereas in marsupials, the female's urethra empties into the urogenital sinus. Females use their urethra only for urinating, but males use their urethra for both urination and ejaculation. The external urethral sphincter is a striated muscle that allows voluntary control over urination. The internal sphincter, formed by the involuntary smooth muscles lining the bladder neck and urethra, receives its nerve supply by the sympathetic division of the autonomic nervous system. The internal sphincter is present both in males and females. Structure The urethra is a fibrous and muscular tube which connects the urinary bladder to the external urethral meatus. Its length differs between the sexes, b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypospadias
Hypospadias is a common variation in fetal development of the penis in which the urethra does not open from its usual location in the head of the penis. It is the second-most common birth abnormality of the male reproductive system, affecting about one of every 250 males at birth. Roughly 90% of cases are the less serious distal hypospadias, in which the urethral opening (the meatus) is on or near the head of the penis (glans). The remainder have proximal hypospadias, in which the meatus is all the way back on the shaft of the penis, near or within the scrotum. Shiny tissue that should have made the urethra extends from the meatus to the tip of the glans; this tissue is called the urethral plate. In most cases, the foreskin is less developed and does not wrap completely around the penis, leaving the underside of the glans uncovered. Also, a downward bending of the penis, commonly referred to as chordee, may occur. Chordee is found in 10% of distal hypospadias and 50% of proximal h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Embryology Of Urogenital System
Embryology (from Greek ἔμβρυον, ''embryon'', "the unborn, embryo"; and -λογία, ''-logia'') is the branch of animal biology that studies the prenatal development of gametes (sex cells), fertilization, and development of embryos and fetuses. Additionally, embryology encompasses the study of congenital disorders that occur before birth, known as teratology. Early embryology was proposed by Marcello Malpighi, and known as preformationism, the theory that organisms develop from pre-existing miniature versions of themselves. Aristotle proposed the theory that is now accepted, epigenesis. Epigenesis is the idea that organisms develop from seed or egg in a sequence of steps. Modern embryology, developed from the work of Karl Ernst von Baer, though accurate observations had been made in Italy by anatomists such as Aldrovandi and Leonardo da Vinci in the Renaissance. Comparative embryology Preformationism and epigenesis As recently as the 18th century, the prevailing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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