Week 2: Yolk sac - Vitelline duct - Bilaminar disc Mammalian embryogenesis is the process of cell division and cellular differentiation which leads to the development of a mammalian embryo. ... This article or section is in need of attention from an expert on the subject. ... For other uses, see Embryo (disambiguation). ... Fetal (U.S. English; Foetal UK English) development is the process in which a fetus (U.S. English; Foetus UK English) develops during gestation, from the times of conception until birth. ... Human fetus at eight weeks. ... This article does not cite any references or sources. ... 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 . ... Blastulation. ... 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. ... A blastopore is an opening into the archenteron during the embryonic stages of an organism. ... 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 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. ... This article, image, template or category should belong in one or more categories. ...

Week 3: Hensen's node - Gastrula/Gastrulation - Trilaminar embryo Branchial arch (1st) - Branchial pouch - Meckel's cartilage - Somite/Somitomere - Sclerotome - Myotome - Germ layer (Ectoderm, Endoderm, Mesoderm, Chordamesoderm, Paraxial mesoderm, Intermediate mesoderm, Lateral plate mesoderm, Splanchnopleure, Somatopleure) Hensens Node is the organizer for gastrulation in birds. ... 1 - blastula, 2 - gastrula; orange - ectoderm, red - endoderm. ... It has been suggested that epiboly be merged into this article or section. ... It has been suggested that this article or section be merged with Embryogenesis. ... In the development of vertebrate animals, the branchial arches (or pharyngeal arches) develop during the fourth and fifth week in utero as a series of mesodermal outpouchings on the left and right sides of the developing pharynx. ... It has been suggested that this article or section be merged into branchial arch. ... Pharyngeal or branchial pouches form on the endodermal side between the branchial arches, and pharyngeal grooves (or clefts) form from the lateral ectodermal surface of the neck region to separate the arches. ... 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. ... 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. ... 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. ... 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. ... 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. ...

Histogenesis and Organogenesis 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. ...

Glands: Thyroglossal duct A gland is an organ in an animals body that synthesizes a substance for release such as hormones, often into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland). ... 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. ...

Uterine support: Placenta - Umbilical cord (Umbilical artery, Umbilical vein, Wharton's jelly) - Amniotic sac (Amnion, Chorion) The uterus or womb is the major female reproductive organ of most mammals, including humans. ... The placenta is an ephemeral (temporary) organ present in female placental vertebrates during gestation (pregnancy), but a placenta has evolved independently also in other animals as well, for instance scorpions and velvet worms. ... In placental mammals, the umbilical cord is a tube that connects a developing embryo or fetus to its 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. ... A drawing of the amniotic sac from Grays Anatomy. ... For the alien race in Stephen Donaldsons The Gap Cycle, see Amnion (Gap Cycle). ... For the entertainment company see Chorion (company) The chorion surrounds the embryo and other membranes. ...

Limb development: Limb bud - Apical Ectodermal Ridge/AER The vertebrate limb arises out of a general morphogenetic area called a limb field. ... In embryology, the limb bud is a structure formed by the developing limb, derived from lateral plate mesoderm[citation needed]. It is intimately related with the apical ectodermal ridge, which secretes factors inducing the initial differentiation of the limb bud. ... The Apical Ectodermal Ridge (AER) is a critical component in vertebrate limb development. ...