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amnion
one of the embryonic membranes of reptiles(including birds) and mammals; encloses a fluid-filled cavity that envelops the embryo
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amniotic egg
the egg of reptiles, including birds; contains a membrane, the amnion, that surrounds the embryo, enclosing it in a watery environment and allowing the egg to be laid on dry land
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cartilage
a form of connective tissue that forms portions of the skeleton; consists of chondrocytes and their extracellular secretion of collagen
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craniate
an animal that has a skull
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mammary gland
a milk-producing gland used by female mammals to nourish their young
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marsupial
a member of the clade Marsupalia, which includes mammals whose young are born at an extremely immature stage and undergo further development in a pouch, where they remain attached to a mammary gland; like kangaroos, opossums, and koalas
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monotreme
a member of the clade Monotremata, which includes mammals that can lay eggs; include platypuses and spiny anteaters
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nerve cord
a major nervous pathway consisting of a cord of nervous tissue extending lengthwise through the body, paired in many vertebrates and unpaired in chordates
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notochord
a stiff but somewhat flexible, supportive rod that extends along the head-to-tail axis and is found in all members of the phylum Chordata at some stage of development
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pharyngeal gill slit
one of a series of openings, located just posterior to the mouth, that connects the throat to the outside environment; present (at some stage of life) in all chordates
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placenta
in mammals, a structure formed by a complex interweaving of the uterine lining and the embryonic membranes, especially the chorion; functions in gas, nutrient, and wastes exchanges between embryonic and maternal circulatory systems, and also secretes the hormones estrogen and progesterone, which are essential to maintaining pregnancy
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placental
referring to a mammals possessing a complex placenta
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post-anal tail
a tail that extends beyond the anus, and contains muscle tissue and the most posterior part of the nerve cord; found in all chordates at some stage of development
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vertebral column
a column of serially arranged skeletal units (the vertebrae) that enclose the nerve cord in vertebrates; the backbone
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vertebrate
an animal that has a vertebral column
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