In reptiles and birds, it arises from endoderm and mesoderm to incorporate the egg yolk into the digestive tract for nourishing the embryo. Primitive yolk sac Yolk Sac The first of four extra-embryonic membranes to form during embryogenesis.After binding to the endometrium, trophoblasts develop into two distinct layers, an inner layer of mononuclear cytotrophoblasts and an outer layer of continuous multinuclear cytoplasm, the syncytiotrophoblasts, which form the early fetal-maternal interface (placenta). Amniotic sac: cavity of fluid that develops “above” the epiblast Epiblast Embryoblast and Trophoblast Development (between epiblast Epiblast Embryoblast and Trophoblast Development and trophoblast Trophoblast Cells lining the outside of the blastocyst.Hypoblast Hypoblast Embryoblast and Trophoblast Development.Epiblast Epiblast Embryoblast and Trophoblast Development.Inner cell mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast → embryoblast Embryoblast Embryoblast and Trophoblast Development → bilaminar disc Bilaminar disc Embryoblast and Trophoblast Development :.Placenta, Umbilical Cord, and Amniotic Cavity and membranes The placenta produces an array of steroid, protein and peptide hormones (placental hormones). It includes a fetal portion (chorionic villi) derived from trophoblasts and a maternal portion (decidua) derived from the uterine endometrium. Fertilization and First Week → placenta Placenta A highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products. Outer cell mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast → trophoblast Trophoblast Cells lining the outside of the blastocyst.The cells then begin differentiating into outer and inner cell masses. Fertilization and First Week (ball of cells) undergoes a process called blastulation, in which a cavity begins to form. Morula is the stage before blastula in non-mammalian animals or a blastocyst in mammals. It resembles a cluster of mulberries with two types of cells, outer cells and inner cells. The morula Morula An early embryo that is a compact mass of about 16 blastomeres. Fertilization and First Week and bilaminar disc Bilaminar disc Embryoblast and Trophoblast Development The inner cell mass gives rise to the embryonic disc and eventual embryo proper. The outer layer of trophoblasts gives rise to extra-embryonic tissues. A blastocyst has two distinctive tissues. Review of Early Embryologic Development Blastocyst Blastocyst A post-morula preimplantation mammalian embryo that develops from a 32-cell stage into a fluid-filled hollow ball of over a hundred cells. Some of these aortic arches go on to form the great vessels near the heart. Cartilage: Histology and muscular components, which are supplied by a cranial nerve (derived from neural crest cells Neural crest cells Gastrulation and Neurulation ), and an artery, known as a pharyngeal aortic arch Aortic arch Mediastinum and Great Vessels: Anatomy. Perichondrium (connective tissue membrane surrounding cartilage) compensates for the absence of vasculature in cartilage by providing nutrition and support. Each pharyngeal arch contains cartilage Cartilage Cartilage is a type of connective tissue derived from embryonic mesenchyme that is responsible for structural support, resilience, and the smoothness of physical actions. Indentations between arches are known as the pharyngeal clefts, or grooves, externally and the pharyngeal pouches internally. Gastrulation and Neurulation and internally by endoderm Endoderm The inner of the three germ layers of an embryo. Gastrulation and Neurulation, which is covered externally by ectoderm Ectoderm The outer of the three germ layers of an embryo. These arches are composed of a central core of mesoderm Mesoderm The middle germ layer of an embryo derived from three paired mesenchymal aggregates along the neural tube. The branchial arches, also known as pharyngeal or visceral arches, are embryonic structures seen in the development of vertebrates that serve as precursors for many structures of the face, neck Neck The part of a human or animal body connecting the head to the rest of the body. Students: Educators’ Pro Tips for Tough Topics. ![]() Maternity Nursing and Care of the Childbearing Family.
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