Complete List of Terms and Definitions for ap biology - embryology

Terms Definitions
Morula Embryo with 16 - 64 cells.
Trophoblast Outer part of blastocyst; forms placenta.
Triploblastic Having three germ layers.
Gastrula The embryo at 2 weeks.
Non-Human Development SSP
Blastula A hollow ball of cells that marks the end of the cleavage stage (128 cells); indeterminate.
Homeobox Makes the cells determinate; turns on the cell's direction.
Endoderm The innermost of the three primary germ layers in animal embryos; lines the archenteron and gives rise to the epithelium of the digestive & respiratory tracts.
Invertebrates An animal without a backbone (95% of all animals)
Diploblastic Having two germ layers.
Porifera Sponges; lack true tissue; no body cavity.
Indeterminate Cleavage A type of embryonic development in deuterostomes in which each cell produced by earl cleavage division retains the capacity to develop into a complete embryo.
Gastrula An embryonic stage in animal development encompassing the formation of three layers: ectoderm, mesoderm, and endoderm.
Cleavage The process of cytokinesis in animal cells, characterized by pinching of the plasma membrane.
Ventral Bottom, or underside
Blastocoel Open cavity during gastrulation.
Coelom A body cavity lined by tissue derived only from mesoderm.
Spiral Cleavage A form of determinate cleavage; the cells of each tier sit in the grooves between cells of adjacent tiers.
Dorsal Top
Notochord .
Extra-Embryonic Membranes Connect to organism, but are not part of it.
Albumin Contains nutrients in an egg.
Body Cavity A fluid or air-filled space between the digestive tract and the body wall.
Pseudocoelomate Fluid filled mesoderm. Ex: Nematoda (roundworm)
Lens Placode The part of the eye that eventually becomes the lens and the cornea.
Blastocyst Embryo with 100 cells. At seven days, it is a hollow ball of cells that implants in the uterine lining endometrium.
Allantois Collects waste in an egg.
Mesoderm The middle primary germ layer in an animal embryo; develops into the inner organs, muscles, cartilage, bone, and blood.
Metamorphosis A developmental transformation that turns an animal larva into either an adult or an adult-like stage that is not yet sexually mature.
Anterior Front, or head
Optic Vessicle The part of the eye that eventually becomes the retina.
Radial Symmetry Symmetry in which the body is shaped like a pie or flowerpot (lacking distinct left and right sides) and can be divided into mirror image halves by any plane through its central axis.
Radial Cleavage A form of indeterminate cleavage; the tiers of the cells are aligned one above the other.
Blastopore In a gastrula, the opening of the archenteron that typically develops into the anus in deuterostomes and the mouth in protostomes.
Coelomates Animals that possess true coelom.
Human Development RED
Chorion Second layer in egg; protect embryo from gases/other
Cnideria Jellyfish; no body cavity.
Body Plan In animals, a set of morphological and developmental traits that are integrated into a functional whole -- the living animal.
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 outpockets of mesodermal tissue.
Archenteron The endoderm-lined cavity, formed during gastrulation, that develops into the digestive tract of an animal.
Larva A free-living, sexually immature form in some animal life cycles that may differ from the adult animal in morphology, nutrition, and habit.
Posterior Rear, or tail end
Ectoderm The outermost of the three primary germ layers in animal embryos; gives rise to the nervous system, epidermis, lens, epithelial tissue of one's oral & nasal cavities, and glands.
Amnion Serves as a shock absorber in an egg.
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.
Cephalization An evolutionary trend toward the concentration of sensory equipment at the anterior end of the body.
Neural Plate .
Determinate Cleavage A type of embryonic development in protostomes that rigidly casts the developmental fate of each embryonic cell very early.
Protostome Development In animals, a developmental mode distinguished by the development of the mouth from the blastopore; often also characterized by spiral cleavage and by the body cavity forming when solid masses of mesoderm split.
Bilateral Symmetry Symmetry in which a central longitudinal plane divides the body into two equal but opposite halves.
Zygote Sperm and egg
Cortical Reaction Triggered by the Acrosomal Reaction; calcium is released in the cytoplasm, causing a change in the cortical granules. The sperm fuses with the plasma membrane and fertilizes the envelope. The Cortical Reaction prevents polyspermy.
Yolk Provides protein for growth in an egg.
Acrosomal Reaction The initial fusion of the sperm to the egg; enzymes digest a hole in the egg's vitelline layer and the sperm fuses with the plasma membrane.
Acoelomate Solid mesoderm; no body cavity. Ex: Platyhelmenthies (flatworm)
Progressive Induction One group of cells influences development of another group of cells.
Eucoelomates SSP: Arthropoda, Mollusca, Annelida; RED: Chordata, Echinodermata
Dorsal Blastiporal Lip .
Embryo A dividing, growing cell (right after zygote)