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| The material substances in the egg that influence the course of early development by regulating the expression of genes that affect the developmental fate of cells |
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| The structural and functional divergence of cells as they become specialized during a multicellular organism's development; dependent on the control of gene expression |
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| The development of body shape and organization |
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| The discharge of a sperm's acrosome when the sperm approaches an egg |
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| A vesicle at the tip of a sperm cell that helps the sperm penetrate the egg |
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| The depolarization of the egg membrane within 1-3 seconds after sperm binding to the vitelline layer; The reaction prevents additional sperm from fusing with the egg's plasma membrane |
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| Exocytosis of enzymes from cortical granules in the egg cytoplasm during fertilization |
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| Vesicles located just under the plasma membrane of an egg cell that undergo exocytosis during the cortical reaction |
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| the swelling of the vitelline layer away from the plasma membrane |
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| The formation of the fertilization envelope and other changes in the egg's surfce that prevent fusion of the egg with more than one sperm |
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| The extracellular matrix of a mammalian egg |
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| A small cell of an early embryo |
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| A solid ball of blastomeres formed by earl y cleavage |
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| The fluid-filled cavity that forms in the center of the blastula embryo |
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| The hollow ball of cells marking the end stage of cleavage during early embryonic development |
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| Nutrients stored in an egg |
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| The portion of the egg where most yolk is concentrated |
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| The portion of the egg where the least yolk is concentrated |
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| A light-gray region of cytoplasm located near the equator of the egg on the side opposite the sperm entry |
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| Incomplete division of yolk-rich egg, characteristic of avian development |
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| Complete division of the egg, as in eggs having little yolk (seaurchin) or a moderate amount of yolk (frog) |
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| An embryonic cap of dividing cells resting on a large undivided yolk |
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| The formation of a gastrula from a blastula |
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| The 3 layered, cup shaped embryonic stage |
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| 3 main layers that form the various tissues and organs of an animal body |
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| 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 |
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| The innermost of the three primary germ layers in animal embroys; lines the archenteron and gives rise to the liver, pancreas, lungs, and the lining of the digestive tract |
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| The middle primary germ layer of an eraly embryo that develops into the notochord, the lining of the coelom, muscles, skeleton, gonads, kidneys, and most of the circulatory system |
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| The endodermlined cavity, formed during the gastrulation process, that develops into the digestive tract of an animal |
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| The opening of the archenteron in the gastrula that develops into the mouth in protostomes and the anus in deuterostomes |
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| The dorsal side of the blastopore |
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| Cells rolling over the edge of the lip of the blastopore into the interior of the embryo during gastrulation |
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| Large food-laden endodermal cells surrounded by the blastopore of an amphibian gastrula |
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| A groove on the surface of an early avian embryo along the future long axis of the body |
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| The development of organ rudiments from the three germ layers |
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| A longitudinal, flexible rod that runs along the dorsal axis of an animal's body in thefuture position of the vertebral column |
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| A tube of cells running along the dorsal axis of the body, just dorsal to the notochord; it will give rise to the central nervous system |
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| A band of cells along the border where the neural tube pinches off from the ectoderm; The cells migrate to various parts of the embryo and form the pigment cells in the skin, bones of the skull, the teeth, the adrenal glands, and parts of the peripheral nervous system |
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| Paired blocks of mesoderm just lateral to the notochord of a vertebrate embryo |
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