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Encyclopedia > Urethral groove

The 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. Failure of complete closure results in a hypospadias. The penis (plural penises or penes) or phallus is an external male sexual organ. ... Female anatomy In anatomy, the urethra is a tube which connects the urinary bladder to the outside of the body. ... Hypospadias is a birth defect of the urethra in the male that involves an abnormally placed urethral meatus (opening). ...

Mammalian embryogenesis/Embryology and Fetal development - edit

Embryo: Zygote | Morula | Blastula/Blastomere/Blastosphere | Gastrula/Gastrulation | Fetus | Carnegie stages Mammalian embryogenesis is the process of cell division and cellular differentiation which leads to the development of a mammalian embryo. ... Embryology is the branch of developmental biology that studies embryos and their development. ... Fetal development is the process in which a fetus develops during gestation, from the time of conception until birth. ... Embryos (and one tadpole) of the wrinkled frog (Rana rugosa). ... This article or section does not cite its references or sources. ... Morula is a stage of embryonic development in animals, including the 16-cell phase, the 32-cell phase, and the 64-cell phase. ... Blastulation. ... A blastomere is the structure which results from the divisions of a fertilised egg during embryonic development . ... The hollow globe or sphere formed by the arrangement of the blastomeres on the periphery of an impregnated ovum. ... 1 - blastula, 2 - gastrula; orange - ectoderm, red - endoderm. ... 1 - blastula, 2 - gastrula; orange - ectoderm, red - endoderm. ... Fetus at eight weeks Foetus redirects here. ... In embryology, Carnegie stages are a standardized system of 23 stages used to provide a unified developmental chronology of the embryo. ...

General: Archenteron | Blastopore | Hensen's node | Germ layer (Ectoderm, Endoderm, Mesoderm) | Histogenesis | Organogenesis | Branchial arch (1st) | Meckel's cartilage | Somite/Somitomere | Proctodeum | Rathke's pouch | Thyroglossal duct | Vitelline duct The archenteron is an indentation that forms early on in a developing blastula. ... A blastopore is an opening into the archenteron during the embryonic stages of an organism. ... Hensens Node is the organizer for gastrulation in birds. ... It has been suggested that organogenesis be merged into this article or section. ... The ectoderm is outermost of the three germ layers of the developing embryo, the other two being the mesoderm and the endoderm. ... The endoderm, sometimes refered to as entoderm, is one of the three germ layers of the developing embryo, the other two being the ectoderm and the mesoderm. ... The mesoderm is one of the three germ layers in the early developing embryo, the other two layers being the ectoderm and the endoderm. ... An Introduction to Histogenesis Histogenesis is defined as the formation of tissues and organs from undifferentiated cells (Encarta Dictionary). ... Organogenesis is a stage of animal development where the ectoderm, endoderm, and mesoderm are formed. ... Schematic of developing fetus with first, second and third arches labeled. ... It has been suggested that this article or section be merged into branchial arch. ... The cartilaginous bar of the mandibular arch is formed by what are known as Meckel’s cartilages (right and left) ; above this the incus is developed. ... In the developing vertebrate embryo, somites are masses of mesoderm distributed along the two sides of the neural tube and that will eventually become dermis (dermatome), skeletal muscle (myotome), and vertebrae (sclerotome). ... In the developing vertebrate embryo, the somitomeres are loose masses of paraxial mesoderm derived cells that form along each side of the neural tube towards the end of the third gestational week. ... A proctoduem is the back ectodermal part of an alimentary canal. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... The thyroglossal duct is an embryological anatomical structure which forms the connection between the initial area of development of the thyroid gland and its final position. ...

Circulatory system: Bulbus cordis | Foramen ovale | Ductus venosus | Ductus arteriosus A circulatory system (sometimes cardiovascular system) is an organ system that moves substances to and from cells; it can also help stabilize body temperature and pH (part of homeostasis). ... When the heart assumes its S-shaped form the bulbus cordis lies ventral to and in front of the primitive ventricle. ... In the fetal heart, the foramen ovale allows blood to enter the left atrium from the right atrium. ... In the fetus, the ductus venosus connects the left umbilical vein with the upper inferior vena cava. ... In the developing fetus, the ductus arteriosus (DA) is a shunt connecting the pulmonary artery to the aortic arch that allows much of the blood from the right ventricle to bypass the fetus fluid-filled lungs. ...

Nervous system: Neurula | Neurulation | Neural crest | Notochord | Neuromere | Neural development The nervous system of an animal coordinates the activity of the muscles, monitors the organs, constructs and also stops input from the senses, and initiates actions. ... A Neurula is an embryo at the early stage of development in which neurulation occurs. ... Neurulation is a part of organogenesis in vertebrate embryos. ... The neural crest, a component of the ectoderm, is one of several ridgelike clusters of cells found on either side of the neural tube in vertebrate embryos. ... The notochord is a flexible rod-shaped body found in embryos of all chordates. ... Neuromeres are transient segments during the early development of the human brain. ... The study of neural development draws on both neuroscience and developmental biology to describe the cellular and molecular mechanisms by which complex nervous systems emerge during embryonic development and throughout life. ...

Urinary/Reproductive system: Wolffian duct | Müllerian duct | Mesonephros | Fetal genital development | Urogenital folds | Gubernaculum | Urethral groove | Urogenital sinus | Ureteric bud | Kidney development The urinary system is the organ system that produces, stores, and carries urine. ... A reproductive systems is the ensembles and interactions of organs and or substances within an organism that stricly pertain to reproduction. ... The Wolffian duct (also known as archinephric duct, Leydigs duct, and the mesonephric duct) is an paired organ found in mammals including humans during embryogenesis. ... The Müllerian ducts are paired ducts of the embryo which empty into the cloaca, and which in the female develop into the upper vagina, cervix, uterus and oviducts; in the male they disappear except for the vestigial vagina masculina and the appendix testis. ... The mesonephros (Latin for middle kidney) is one of three excretory organs that develop in vertebrates. ... This article or section is in need of attention from an expert on the subject. ... The urogenital folds are an embryological structure which give rise to a portion of the external genitalia. ... The gubernaculum is a fold of peritoneum which attaches to the caudal end of the testes. ... The urogenital sinus (also known as the persistent cloaca) is a part of the human body while it is an embryo. ... The Ureteric bud is a portion of the mesonephric duct. ... In humans, the metanephros (adult kidney) begins as an aggregate of mesenchymal cells that are detectable by the fifth gestational week as two small areas in the intermediate mesoderm close to the pelvic aorta. ...

Uterine support: Placenta | Umbilical cord (Umbilical artery, Umbilical vein, Wharton's jelly) | Amniotic sac (Amnion, Chorion) | Yolk sac | Allantois | Trophoblast (Cytotrophoblast | Syncytiotrophoblast | Gestational sac) Female internal reproductive anatomy The uterus or womb is the major female reproductive organ of most mammals, including humans. ... The placenta is an ephemeral (temporary) organ present only in female placental mammals during gestation (pregnancy). ... A newborn at 45 seconds. ... Umbilical arteries carry deoxygenated blood from the fetus to the placenta in the umbilical cord. ... Fetal circulation; the umbilical vein is the large, red vessel at the far left The umbilical vein is a blood vessel present during fetal development that carries oxygenated blood from the placenta to the growing fetus. ... Whartons jelly is a gelatinous substance within the umbilical cord. ... amniotic sac The amniotic sac is a tough but thin transparent pair of membranes, which hold a developing embryo (and later fetus) until shortly before birth. ... The amniotic sac is a tough but thin transparent pair of membranes which holds a developing embryo (and later fetus) until shortly before birth. ... Chorion can refer to the following things: Chorion is the outer membrane of the amniotic sac. ... The yolk sac is the first element seen in the gestational sac during pregnancy, usually at 5 weeks gestation. ... Allantois is a part of a developing animal embryo. ... The trophoblast (from Greek threphein: to feed) is considered to be the first of all embryonic annexes. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... Syncytiotrophoblasts are cells found in the placenta of human embryos. ... The gestational sac is the only available intrauterine structure that can be used to determine if an intrauterine pregnancy (IUP) exists, until the embryo is identified. ...



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