Germ layer: Ectoderm (Neuroectoderm) - Endoderm - Mesoderm (Chorda-, Paraxial, Intermediate, Lateral plate) - Splanchnopleure/Somatopleure
Human embryogenesis is the process of cell division and cellular differentiation of the human embryo during early prenatal development. ... This article or section is in need of attention from an expert on the subject. ... For other uses, see Embryo (disambiguation). ... This article is about prenatal development in humans. ... For other uses, see Fetus (disambiguation). ... This article does not cite any references or sources. ... The following list describes a timeline of specific changes in human prenatal development by week of gestational age. ... It has been suggested that Biparental zygote be merged into this article or section. ... 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 blastocyst is an early stage of the human (or any other mammal) development early in pregnancy. ... The inner cell mass is surrounded by the single cell layer of cells called trophoblast. ... This article, image, template or category should belong in one or more categories. ... The hypoblast is a tissue type from the inner cell mass. ... In embryology, the epiblast is a feature present during gastrulation. ... The archenteron is an indentation that forms early on in a developing blastula. ... The primitive streak is a structure that forms during the early stages of avian, reptilian and mammalian embryonic development. ... It has been suggested that this article or section be merged with Embryogenesis. ... The primitive knot (or Primitive node) is the organizer for gastrulation in vertebrates. ... A blastopore is an opening into the archenteron during the embryonic stages of an organism. ... A shallow groove, the primitive groove, appears on the surface of the primitive streak, and the anterior end of this groove communicates by means of an aperture, the blastophore, with the yolk-sac. ... 1 - blastula, 2 - gastrula; orange - ectoderm, red - endoderm. ... It has been suggested that epiboly be merged into this article or section. ... Organs derived from each germ layer. ... The ectoderm is outermost of the three germ layers of the developing embryo, the other two being the mesoderm and the endoderm. ... Neuroectoderm is the term for ectoderm which receives inhibitory signals from proteins such as noggin, which leads to the development of the nervous system from this tissue. ... Endoderm is one of the germ layers formed during animal embryogenesis. ... The mesoderm is one of the three germ layers in the early developing embryo, the other two layers being the ectoderm and the endoderm. ... Chordamesoderm is a type of mesoderm that lies along the central axis, under the neural tube. ... Paraxial mesoderm is the area of mesoderm that forms just lateral to the neural tube on both sides. ... Intermediate mesoderm is a type of mesoderm that is located between the paraxial mesoderm and the lateral plate. ... Lateral plate mesoderm (or hypomere) is a type of mesoderm that is found at the periphery of the embryo. ... In the anatomy of an embryo, the splanchnopleure is a structure created during embryogenesis when the lateral mesoderm splits into two layers. ... When the lateral mesoderm splits into two layers, the outer (or somatic) one becomes applied to the inner surface of the ectoderm, and with it forms the somatopleure. ...

Blastocoele - Yolk sack/exocoelomic cavity - Heuser's membrane - Vitelline duct 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. ... In vertebrate embryonic development, a group of embryonic tissues formed from somites that develop into the vertebrae. ... In vertebrate embryonic development, a group of tissues formed from somites that develop into the body wall muscle. ... The cutis plate is the dorsal portion of the paraxial mesoderm somite which gives rise to dermis. ... This article is about female reproductive anatomy. ... 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. ... A blastocoel(e) or blastocele or cleavage cavity or segmentation cavity is the central region of a blastocyst. ... The yolk sac is the first element seen in the gestational sac during pregnancy, usually at 5 weeks gestation. ... At the end of the fourth week the yolk-sac presents the appearance of a small pear-shaped vesicle (umbilical vesicle) opening into the digestive tube by a long narrow tube, the vitelline duct. ...

Umbilical cord (Umbilical artery, Umbilical vein, Wharton's jelly) - Allantois In placental mammals, the umbilical cord is a tube that connects a developing embryo or fetus to the placenta. ... 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. ... Allantois is a part of a developing animal embryo. ...

Placenta - Decidua (Decidual cells) - Chorionic villi/Intervillous space - Gestational sac (Amnion/Amniotic sac/Amniotic cavity, Chorion) The placenta is an ephemeral (temporary) organ present in female placental vertebrates, such as some mammals and sharks during gestation (pregnancy). ... Decidua is the term for the uterine lining (endometrium) during a pregnancy. ... Before the fertilized ovum reaches the uterus, the mucous membrane of the body of the uterus undergoes important changes and is then known as the decidua. ... Chorionic villi are villi that sprout from the chorion, in order to give a maximum area of contact with the maternal blood. ... The trophoblast proliferates rapidly and forms a network of branching processes which cover the entire ovum and invade and destroy the maternal tissues and open into the maternal bloodvessels, with the result that the spaces in the trophoblastic network are filled with maternal blood; these spaces communicate freely with one... 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. ... For the alien race in Stephen Donaldsons The Gap Cycle, see Amnion (Gap Cycle). ... A drawing of the amniotic sac from Grays Anatomy. ... 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. ... For the entertainment company see Chorion (company) The chorion surrounds the embryo and other membranes. ...