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| 2603445047 | Polyspermy | - The situation in which an egg has been fertilized by more than one sperm. | 0 | |
| 2603446182 | Acrosomal Reaction | - The discharge of hydrolytic enzymes from the acrosome, a vesicle in the tip of a sperm, when the sperm approaches or contacts an egg. | 1 | |
| 2603446183 | Acrosome | - A vesicle in the tip of a sperm containing hydrolytic enzymes an other proteins that help the sperm reach the egg. | 2 | |
| 2603446184 | Acrosomal Process | - The structure at the of a sperm that elongates and penetrates the jelly coat of an egg, the tip of which contains proteins that associate with receptors on the plasma membrane of the egg. | 3 | |
| 2603449218 | Fast Block to Polyspermy | - Occurring within 1-3 seconds of a sperm binding to an egg, this process prevents fusion of plasma membrane with additional sperm through depolarization. | 4 | |
| 2603449900 | Slow Block to Polyspermy | - The process preventing fusion additional sperm to egg plasma membrane, occurring after depolarization, in which vesicles beneath the egg plasma membrane fuse with it, triggering a cortical reaction. | 5 | |
| 2603449901 | Cortical Reaction | - The process in which enzymes and other macromolecules lift the vitelline layer away from the egg and harden the layer into a protective fertilization envelope. | 6 | |
| 2603453443 | Zona Pellucida | - The extracellular matrix surrounding a mammalian egg. | 7 | |
| 2603453444 | Cleavage | - The succession of rapid cell divisions without significant growth during early embryonic development that converts the zygote to a ball of cells. | 8 | |
| 2603454609 | Blastomere | - An early embryonic cell arising during the cleavage stage of an early embryo. | 9 | |
| 2603454610 | Blastula | - A hollow ball of cells that marks the end of the cleavage stage during early embryonic development in animals. | 10 | |
| 2603456010 | Blastocoel | - The fluid-filled cavity that forms in the center of a blastula. | 11 | |
| 2603456011 | Yolk | - Nutrients stored in an egg. | 12 | |
| 2603456740 | Vegetal Pole | - The point at the end of an egg in the hemisphere where most yolk is concentrated; opposite of animal pole | 13 | |
| 2603456741 | Animal Pole | - The point at the end of an egg in the hemisphere where the least yolk is concentrated; opposite of vegetal pole. | 14 | |
| 2603456742 | Cleavage Furrow | - The first sign of cleavage in an animal cell; a shallow groove around the cell in the cell surface near the old metaphase plate. | 15 | |
| 2603460263 | Holoblastic | - Referring to a type of cleavage in which there is complete division of the egg; occurs in eggs that have little yolk (such as those of the sea urchin) or a moderate amount of yolk (such as those of the frog). | 16 | |
| 2603462837 | Meroblastic | - Referring to a type of cleavage in which there is incomplete division of a yolk-rich egg, characteristic of avian development. | 17 | |
| 2603462838 | Morphogenesis | - The development of the form of an organism an its structures. | 18 | |
| 2603464390 | Gastrulation | - In animal development, a series of cell and tissue movements in which the blastula-stage embryo folds inward, producing a three-layered embryo, the gastrula. | 19 | |
| 2603464391 | Organogenesis | - The process in which organ rudiments develop from the three germ layers after gastrulation. | 20 | |
| 2603464392 | Gastrula | - An embryonic stage in animal development encompassing the formation of three layers: ectoderm, mesoderm, and endoderm. | 21 | |
| 2603465387 | Germ Layers | - Three main layers in a gastrula that will form the various tissues and organs of an animal body. | 22 | |
| 2603465388 | Ectoderm | - The outermost of the three primary germ layers in animal embryos; gives rise to the outer covering and, in some phyla, the nervous system, inner ear, and lens of the eye. | 23 | |
| 2603465389 | Endoderm | - The innermost of the three primary germ layers in animal embryos; lines the archenteron and gives rise to the liver, pancreas, lungs, and the lining of the digestive tract in species that have these structures. | 24 | |
| 2603465390 | Mesoderm | - The middle primary germ layer in a triploblastic animal embryo; develops into the notochord, the lining of the coelom, muscles, skeleton, gonads, kidneys, and most of the circulatory system in species that have these structures. | 25 | |
| 2603466662 | Archenteron | - The endoderm-lined cavity, formed during gastrulation, that develops into the digestive tract of an animal. | 26 | |
| 2603466663 | Blastopore | - In a gastrula, the opening of the archenteron that typically develops into the anus in deuterostomes and the mouth in protostomes. | 27 | |
| 2603468256 | Deuterostome Development | - In animals, a developmental mode distinguished by the development of the anus from the blastopore; often also characterized by radial cleavage and by the body cavity forming as out-pockets of mesodermal tissue. | 28 | |
| 2603469248 | Dorsal Lip | The region above the blastopore on the dorsal side of the amphibian embryo. | 29 | |
| 2603469987 | Epiblast | The layer of an early embryo that will give rise to the embryo-proper (rather than the extra-embryonic membranes). | 30 | |
| 2603469988 | Hypoblast | 31 | ||
| 2603469989 | Primitive Streak | - A thickening along the future anterior-posterior axis on the surface of an early avian or mammalian embryo, caused by a piling up of cells as they congregate at the midline before moving into the embryo | 32 | |
| 2603472408 | Blastocyst | - The blastula stage of mammalian embryonic development, consisting of an inner call mass, a cavity, and an outer layer, the trophoblast. in humans, this forms 1 week after fertilization. | 33 | |
| 2603472409 | Inner Cell Mass | - An inner cluster of cells at one end of a mammalian blastocyst that subsequently develops into the embryo proper an some of the extraembryonic membranes. | 34 | |
| 2603472410 | Trophoblast | - The outer epithelium of a mammalian blastocyst. It forms the fetal part of the placenta, supporting embryonic development but not forming part of the embryo proper. | 35 | |
| 2603476030 | Extraembryonic Membranes | - Four membranes (yolk sac, amnion, chorion, and allantois) located outside the embryo that support the developing embryo in reptiles and mammals. | 36 | |
| 2603479653 | Amniotes | - A member of a clade of tetrapods named for a key derived character, the amniotic egg, which contains specialized membranes, including the fluid-filled amnion, that protect the embryo. This includes mammals as well as birds and other reptiles. | 37 | |
| 2603479654 | Neurulation | - The early steps in the formation of the brain and spinal cord in vertebrates. | 38 | |
| 2603480663 | Notochord | - A longitudinal, flexible rod made of tightly packed mesodermal cells that runs along the anterior-posterior axis of a chordate in the dorsal part of the body | 39 | |
| 2603480664 | Neural Plate | - The structure formed from ectoderm above the notochord, due to signaling molecules secreted by mesodermal cells and other tissues. | 40 | |
| 2603480665 | Induction | - A process in which a group of cells or tissues influences the development of another group through close-range interactions. | 41 | |
| 2603480666 | Neural Tube | - The structure formed from rolling of the neural plate, running anterior-posterior along the embryo axis. | 42 | |
| 2603482033 | Spina Bifida | - The most common birth defect in the US, in which a portion of the neural tube fails to develop or close properly. | 43 | |
| 2603482034 | Neural Crest Cells | - The band of cells which develop along the borders where the neural tube pinches off from the ectoderm. | 44 | |
| 2603482035 | Somite | - One of a series of blocks of mesoderm that exist in pairs just lateral to the notochord in a vertebrate embryo. | 45 | |
| 2603485359 | Convergent Extension | - A process in which the cells of a tissue layer rearrange themselves in such a way that the sheet of cells becomes narrower (converges) an longer (extends). | 46 | |
| 2603486356 | Extracellular Matrix (ECM) | - The meshwork surrounding animal cells, consisting of glycoproteins, polysaccharides, and proteoglycans synthesized and secreted by cells. | 47 | |
| 2603496643 | Apoptosis | - A type of programmed cell death, which is brought about by activation of enzymes that break down many chemical components in the cell. | 48 | |
| 2603497425 | Determination | - The progressive restriction of developmental potential in which the possible fate of each cell becomes more limited as an embryo develops. At the end of determination, a cell is committed to its fate. | 49 | |
| 2603497426 | Differentiation | - The process by which a cell or group of cells becomes specialized in structure and function. | 50 | |
| 2603497427 | Fate Maps | - A territorial diagram of embryonic development that displays the future derivatives of individual cells and tissues. | 51 | |
| 2603499649 | Germ Cells | - The cells that give rise to eggs or sperm. | 52 | |
| 2603501589 | Cortical Rotation | - | 53 | |
| 2603503024 | Developmental Potential | - The range of structures to which a cell can give rise. | 54 | |
| 2604015863 | Totipotent | - Cells that are able to develop into any type of cell found in the body | 55 | |
| 2603505949 | Pattern Formation | - The development of a multicellular organism's spatial organization, the arrangement of organs and tissues in their characteristic places in three-dimensional space. | 56 | |
| 2603505950 | Positional Information | - Molecular cues that control pattern formation in an animal or plant embryonic structure by indicating a cell's location relative to the organism's body axes. These cues elicit a response by genes that regulate development. | 57 | |
| 2603507899 | Apical Ectodermal Ridge (AER) | - A thickened area of ectoderm at the tip of a limb bud that promotes outgrowth of the limb bud. | 58 | |
| 2603509174 | Zone of Polarizing Activity (ZPA) | - A block of mesoderm located just under the ectoderm where the posterior side of a limb bud is attached to the body; required fro proper pattern formation along the anterior-posterior axis of the limb. | 59 | |
| 2603815898 | Defining Characteristics of Animals | 1) Notochord --> Vertebral column 2) Dorsal hollow nerve cord --> Brain + Spinal cord 3) Post-anal tail --> Disappears in humans 4) Pharyngeal gill slits --> Hyoid bone in humans | 60 |
