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18 Cards in this Set
- Front
- Back
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typical cellular reproduction in chordates? |
-two gamete types: egg & sperm
-fusion of gametes produce zygote -zygte undergoes process of cleavage; rapid/synchronous cell division = blastomeres |
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egg types |
microlecithal: little yolk mesolecithal: intermediate amount of yolk and may be: -isolecithal: even distributed -telolecithal: concentrated near one end *vegetal pole: yolky end *animal pole: embryo macrolecithal: large amount of yolk; cytoplasm restricted to small patch @ one end = blastodisc |
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division of cells in eggs
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microlecithal (amphioxus) & mesolecithal (frog): holoblastic & divide completely macrolecithal (chick): meroblastic & restricted to cytoplasm @ one end of egg, the blastodisc |
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microlecithal cell division amphioxus pt. i |
early cleavage produces solid balls of cells = morula continued div. = blastula (hollow ball) tissue differentiates during gastrulation = double layered ball of cells (gastrula) |
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microlecithal cell division amphioxus pt. ii |
blastocoele invaginated by new cavity = archenteron (primitive gut) outer wall of cells = germ layer = ectoderm cells of archenteron become 2 germ layers: |
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microlecithal cell division amphioxus mesoderm |
produced via pinching off of dorsolateral portions of innter layer ; hollows in meso. become the coelom center of dorsal region of inner cell layer = chrodamesoderm (becomes notochord) and induces changes in overlying ectoderm |
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microlecithal cell division amphioxus process of induction |
whereby one tissue causes changes in nearby tissue by release of chemical signals next stage: neurulation chrodameso. induces ecto. thickening to produce flat neural plate - edges of wrap upward to form neural tube |
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microlecithal cell division amphioxus product of gastrulation |
three distinct germ layers: - ectoderm: skin - mesoderm: coelomic cavity & neural structures - endoderm: lining gut |
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mesolecithal cell division amphibian - frog |
blastocoele restricted to animal pole of egg ; vegetal pole is laden with yolk as cells move interior via involution, replaced by other cells streaming toward blastopore = movement called epiboly cells involut. over dorsal lip = chordamesoderm |
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macrolecithal cell division chicken |
cleavage results in a sheet of cells (epiblast) overlying blastocoele cells of the blastoderm migrate in thru struct. = primitive streak ; cells enter blastocoele and create 2 internal layers: *lower hypoblast & midde layer of mesoderm |
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general amniote neurulation |
embryo appears to be flattened out ; germ layers arranged like cake on massive yolk as neural tube closes, cells escape from lateral sides: neural crest --- meso. proper splits to produce coelom |
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general amniote neurulation the neural crest |
cells migrate thru body ; produce: - cartilaginous gill arches - anterior braincase - parts of teeth - pigment cells - some neurons @ end of neuru., meso. differentiates into blocks = somites |
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general amniote neurulation amphibian gastrula: 3 divisions of somite differentiations |
somite differentiates into: outer dermatome ; intermediate myotome; and inner sclerotome |
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general amniote neurulation amphibian gastrula: two subdivisions of intermediate mesoderm |
intermed. mesoderm differentiates into: upper genital ridge and lower nephric ridge |
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general amniote neurulation amphibian gastrula: two subdivisions of laterplate mesoderm |
the lateral pl. differentiates into: outer somatic portion & inner splanchnic portion: -somatic: combines w/ outer body wall = somatopleure -splanchnic: combines w/ endoderm = splanchnopleure |
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extraembryonic membranes |
cleidoic egg defined by presence of various extraebryonic membranes including: - yolk sac - amnion - chorion - allantois |
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extraembryonic membranes trilaminar vs. bilaminar |
trilaminar: portions of all three germ layers contribute to yolk sac (macrolecithal fishes) bilaminar: only splanchnic layer of the lateral plate & endoderm contribute to yolk sac |
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extraembryonic membranes amniotes chick embryo |
outermost layers of developing yolk sac peel away & grow up above top of embryo where they meet to form 2 other membranes: amnion: forms protective pouch around embryo itself ; becomes filled w/ amniotic fluid & chorion final membrane = allantois ; an extension of posterior portion of archenteron ; portions of splanchn. layer of lat. pl. & endo. contribute to membrane ; resevoir for waste products |
