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Primordial Phallus
In embryology, the primordial phallus refers to the clitoris of a female or the penis in the male, particularly during fetal development of the urinary and reproductive organs, before sexual differentiation is evident. This is also the case for the immature male analog, the immature glans penis. Image:Primordial_phallus,_low_mag.jpg, Micrograph of the primordial phallus, H&E stain. Image:Primordial_phallus,_intermed._mag.1.jpg, Micrograph of the primordial phallus, H&E stain. See also * Aphallia * Genital tubercle A genital tubercle or phallic tubercle is a body of tissue present in the development of the reproductive system. It forms in the ventral, caudal region of mammalian embryos of both sexes, and eventually develops into a primordial phallus. In the ... Embryology of urogenital system {{developmental-biology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Embryology
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 prevailin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clitoris
The clitoris ( or ) is a female sex organ present in mammals, ostriches and a limited number of other animals. In humans, the visible portion – the glans – is at the front junction of the labia minora (inner lips), above the opening of the urethra. Unlike the penis, the male homologue (equivalent) to the clitoris, it usually does not contain the distal portion (or opening) of the urethra and is therefore not used for urination. In most species, the clitoris lacks any reproductive function. While few animals urinate through the clitoris or use it reproductively, the spotted hyena, which has an especially large clitoris, urinates, mates, and gives birth via the organ. Some other mammals, such as lemurs and spider monkeys, also have a large clitoris. The clitoris is the human female's most sensitive erogenous zone and generally the primary anatomical source of human female sexual pleasure. In humans and other mammals, it develops from an outgrowth in the embry ... [...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] |
Development Of The Urinary And Reproductive Organs
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 urinary and reproductive organs are developed from the intermediate mesoderm. The permanent organs of the adult are preceded by a set of structures which are purely embryonic, and which with the exception of the ducts disappear almost entirely before birth. These embryonic structures are on either side; the pronephros, the mesonephros and the metanephros of the kidney, and the Wolffian and Müllerian ducts of the sex organ. The pronephros disappears very early; the structural elements of the mesonephros mostly degenerate, but the gonad is developed in their place, with which the Wolffian duct remains as the duct in males, and the Müllerian as that of the female. Some of the tubules of the mesonephro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sexual Differentiation
Sexual differentiation is the process of development of the sex differences between males and females from an undifferentiated zygote. Sex determination is often distinct from sex differentiation; sex determination is the designation for the development stage towards either male or female, while sex differentiation is the pathway towards the development of the phenotype. In many species, testicular or ovarian differentiation begins with appearance of Sertoli cells in males and granulosa cells in females. As male and female individuals develop from embryos into mature adults, sex differences at many levels develop, such as genes, chromosomes, gonads, hormones, anatomy, and psyche. Beginning with determination of sex by genetic and/or environmental factors, humans and other organisms proceed down different pathways of differentiation as they grow and develop. These processes are not fixed, and can change over one organism's lifetime or over many generations evolutionarily. Sex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glans Penis
In male human anatomy, the glans penis, commonly referred to as the glans, is the bulbous structure at the distal end of the human penis that is the human male's most sensitive erogenous zone and their primary anatomical source of sexual pleasure. It is anatomically homologous to the clitoral glans. The glans penis is part of the male reproductive organs in humans and other mammals where it may appear smooth, spiny, elongated or divided. It is externally lined with mucosal tissue, which creates a smooth texture and glossy appearance. In humans, the glans is a continuation of the corpus spongiosum of the penis. At the summit appears the urinary meatus and at the base forms the corona glandis. An elastic band of tissue, known as the frenulum, runs on its ventral surface. In men who are not circumcised, it is completely or partially covered by the foreskin. In adults, the foreskin can generally be retracted over and past the glans manually or sometimes automatically during an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
H&E Stain
Hematoxylin and eosin stain ( or haematoxylin and eosin stain or hematoxylin-eosin stain; often abbreviated as H&E stain or HE stain) is one of the principal tissue stains used in histology. It is the most widely used stain in medical diagnosis and is often the gold standard. For example, when a pathologist looks at a biopsy of a suspected cancer, the histological section is likely to be stained with H&E. H&E is the combination of two histological stains: hematoxylin and eosin. The hematoxylin stains cell nuclei a purplish blue, and eosin stains the extracellular matrix and cytoplasm pink, with other structures taking on different shades, hues, and combinations of these colors. Hence a pathologist can easily differentiate between the nuclear and cytoplasmic parts of a cell, and additionally, the overall patterns of coloration from the stain show the general layout and distribution of cells and provides a general overview of a tissue sample's structure. Thus, pattern recogniti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aphallia
Aphallia is a congenital malformation in which the phallus (penis or clitoris) is absent. It is also known as penile agenesis in the case of males. The word is derived from the Greek ''a-'' for "not", and ''phallos'' for "penis". It is classified as an intersex variation. Causes Aphallia has no known cause. It is not linked to deficient hormone amounts or action, but rather to a failure of the fetal genital tubercle to form between 3 and 6 weeks after conception. The urethra of an affected child opens on the perineum. Diagnosis Treatment Congenital anomalies like cryptorchidism, renal agenesis/dysplasia, musculoskeletal and cardiopulmonary anomalies are also common (>50% cases), hence evaluation of the patient for internal anomalies is mandatory. Although aphallia can occur in any body type, it is considered a substantially more troublesome problem with those who have testes present, and has in the past sometimes been considered justification for assigning and rearing a genetica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genital Tubercle
A genital tubercle or phallic tubercle is a body of tissue present in the development of the reproductive system. It forms in the ventral, caudal region of mammalian embryos of both sexes, and eventually develops into a primordial phallus. In the human fetus, the genital tubercle develops around week 4 of gestation, and by week 9 becomes recognizably either a clitoris or penis. This should not be confused with the sinus tubercle which is a proliferation of endoderm induced by paramesonephric ducts. Even after the phallus is developed, the term genital tubercle remains, but only as the terminal end of it, which develops into either the glans penis or the glans clitoridis. The genital tubercle is sensitive to dihydrotestosterone and rich in 5-alpha-reductase, so that the amount of fetal testosterone present after the second month is a major determinant of phallus size at birth. See also *Sexual differentiation Sexual differentiation is the process of development of the sex differ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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