development II Flashcards
cytoplasmic specification
intrinsic information is inherited from the mother cell through cell division.
during cytoplasmic specification unequally distributed components of the cytoplasm influence ____ of the cell to a ____ cell type
-commitment
-particular
induction
extrinsic information is received from the cell’s surroundings
each step in developmental hierarchy is a necessary ____ event for the next
-preliminary
both forms of cell specification determine which ___ get expressed and allows for ____ cell function
-genes
-specialized
amniotes
reptiles and mammals for monophyletic group within vertebrates; develop in the amniotic sac
functions of the amniotic sac
-provides an aqueous environment for floating
-serves as protection from mechanical shock adhesions
amniotic egg contains ___ extraembryonic membranes which are…
four
-amnion
-yolk sac
-allantois
-chorion
amniotic egg: what stores yolk to sustain the embryo
yolk sac
amniotic egg: storage of metabolic wastes during development, respiratory surface for exchange of oxygen and carbon dioxide
allantois
amniotic egg: lies beneath eggshell, encloses embryo and other membranes
chorion
later during amniotic egg development, allantois and chorion fuse to form respiratory surface for more oxygen
chorioallantoic membrane
significance of amniotic egg:
-life support system
-made internal fertilization a requirement
-life on land could exist and not dry out
placental mammals
embryo is protected and nourished by the placenta; nourishment from mother
placental mammals: amnion
remains unchanged same function
placental mammals: yolk sac
contains no yolk but is not fluid-filled
-source of stem cells that give rise to blood, lymphoid cells, and gametes
placental mammals: allantois
not needed to store wastes
-contributes to the formation of the umbilical cord
placental mammals: chorion
forms most of the placenta along with the adjacent uterine endometrium
-secretes materials that block normal maternal immune response
what tissues derive from the ectoderm?
-nervous system
-epidermis
-hair
gastrocoel forms primitive gut
-digestive tract lining
-lining of the pharynx and lungs
-most of the liver and pancreas
-thyroid, parathryoid glands, thymus
endoderm
mesoderm
somites
-most muscles, back, body wall, and limbs
-axial skeleton
-dermis of dorsal skin
-heart
