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107 Cards in this Set
- Front
- Back
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differentiation |
changes in gene expression establish cells with specialized structure and function |
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cell division |
-development from adult animal from fertilized egg involves cell division, in which more cells are produced by mitosis |
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morphogenesis |
-the generation of the body form of the animal as differentiated cells end up at their appropriate sites. |
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zygote |
-one formed mitotic divisions begin the developmental activity |
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information storage of the egg |
-initiation of development depends primarily on the DNA in the zygote nucleus and on cytoplasmic determinants |
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cytoplasmic determinants |
- mRNA and protein molecules stored in the cytoplasm -these mRNA proteins direct development until genes of zygote become active |
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tubulin molecules |
-in egg cytoplasm -forms spindles for early cell division. |
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yolk |
-contains nutrients - insects, reptiles and birds contain large amount of yolk, which supplies all of the nutrients for development of the embryo -placental animals have very little yolk |
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polarity |
- unequal distribution of yolk and other components in a mature egg Animal pole: egg nucleus at one end -gives rise to surface structures and anterior end of embryo Vegetal pole: gives rise to internal structures such as gut and posterior end of embryo. -yolk is mostly concentrated here |
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Cleavage |
-soon after fertilization, zygote begins cleavage -a series of mitotic division in which cycles of DNA replication and division occur without the production of new cytoplasm -as result, cytoplasm of egg is partitioned into smaller cells without increasing overall size or mass of embryo |
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Blastomeres |
-cleavage stage cells |
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Morula |
-initial cleavage produces this solid ball or layer of blastomeres -as cleavage continues, the ball or layer hollows out to form Blastula, in which blastomeres enclose a fluid-filled cavity called the Blastocoel |
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Gastrulation |
-after cleavage, blastomeres undergo cellular rearrangements -morphogenetic result is an embryo with three distinct primary cell layers Embryo is termed Gastrula Three germ layers are formed Ectoderm: outer Endoderm: inner Mesoderm: middle -during gastrulation embryos begin to differentiate, becoming different in biochemistry |
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Ectoderm |
-skin and elaborations: hair, feathers - nervous system: brain, spinal cord, peripheral nerves, lens, retina, and cornea of eye, lining of mouth and anus -sweat glands, mammary glands, adrenal medulla and tooth enamel |
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Mesoderm |
-Muscles, most of skeletal system, bones and cartilage -circulatory system, including heart, blood vessels, blood cells -internal reproductive organs, kidneys and outter walls of digestive tract |
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Endoderm |
-Lining of digestive tract, liver, pancreas -lining of respiratory tract, thyroid gland, lining of urethra and urinary bladder |
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totipotent |
-capable of producing all the various types of cells of the adult -fertilized egg -give rise to pluripotent cells |
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pluripotent cells |
-give rise to to most but not all adult cell types -give rise to multi potent cells |
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multi potent cells |
-give rise to cells with particular functions |
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Organegenesis |
-rearrangments of three germ layers to produce tissues and organ -at end of this rearrangement, embryo has body organization characteristic of its species |
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Cellular processes influenced by genetic control and to some extent the environment |
see below |
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Selective cell adhesions |
-cells make or break specific connections to other cell or to the extracellular matrix |
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Induction |
-one group of cells (the inducer cells) causes or influences another nearby group of cells to follow a particular developmental pathway |
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Determination |
-developmetal fate of cell is set, and it is committed to becoming a particular cell |
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Apoptosis |
-programmed cell death, in which tissues no longer required for development are removed |
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Sea Urchin Gastrulation |
-symmetrical pattern -even distribution of yolk Sea Urchin is echinoderm, a type of deuterostome. Cleavage produces a solid mass of blastomeres, the Morula -Gastrulation begins at vegtal pole of the blastula. -as a result of induction, cells in the middle region become elongated causing region to flatten and thicken 3. some cells break loose and migrate to the Blastocoel |
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Primary mesenchyme cells |
- cells that break loose and migrate to blastocoel - move around inside the blasteocel making and breaking cell adhesions until they attach along the ventral side of the blastecoel. -these cells eventually become mesoderm cells, from which larval skeleton is produced |
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invagination |
-next flattened vegetal pole of blastula folds inward from the surface -invaginated region becomes the Archenteron, which is lined with future endoderm cells -its opening at the vegetal pole is called the blastopore |
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Archenteron |
-forms the primitive gut of the sea urchin -makes up endoderm |
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secondary mesenchyme cells |
-form at the top of the archenteron, and these cells eventually become mesoderm cells -they send out extensions that strict across blasteocoel and contact the inside of the ectoderm -these extension eliminate most of the blasteocel |
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mesoderm layer |
- derived from primary and secondary mesenchyme cells that migrate to middle space -give rise to mesodermal organs |
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Blastopore |
- posterior end -opening of archenteron -gives rise to anus or mouth |
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Deuterosome |
-echindoerms and chordates -blastopore develops into anus and mouth forms at opposite end where archenteron contacts and fuses with the ectoderm |
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Protostomes |
-annelids, anthropoids, and mollusk -blastopore develops into mouth and anus forms at the opposite end of gut |
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Amphibian cleavage and gastrulation |
-influenced by unequal distribution of yolk -yolk is concentrated in vegtal half 1. sperm fertilizes egg in animal half -pigment layer of cytoplasm rotates toward site of sperm,exposing gray crescent, at the opposite end of sperm entry |
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Gray cresent |
- established the dorsal-ventral axis of the embryo -gray crescent makes future dorsal side. -first cleavage division runs perpendicular to the long axis of the gray crescent, dividing the crescent into two cells. -if one of the two blastomeres does not recieve gray crescent, it cells divide and produce disorder that stops developing. -it is essential to the development of frog embryos |
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Vertical plane |
-second cleavage division is in 90 degrees from first , producing 4 cell stage |
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Horizontal plane |
-third cell division in the animal half of the egg to produce the 8 cell stage -embyro development continues to produce morula (16-64 cells) and Blastula (128) |
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Gastrulation in frog embryo |
-begins when cells from the animal pole move across the embryo surface and reach the region derived from the gray crescent- dorsal lip of the blastopore |
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Dorsal lip of the blastopore |
- marked by depression from invagination of cells from surface. -inward migration of depression eventually forms a complete circle called the Blastopore |
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Involution |
-cells now migrate into blastopore -cells entering from outer layer spread over internal surface -pigment cell layer of the animal half now expands to cover the entire surface -cells of vegetal half are enclosed by movement and show on outside of yolk plug in blastopore -Blastopore gives rise to anus -continued involution moves cells into the interior and upward forming two layers that line the inside top half of the embryo -uppermost layer- dorsal mesoderm - layer beneath it- endoderm, containing cells from outer surface and yolk interior -ventral mesoderm begins to be induced near vegetable pole -archenteron replaces the blastecoel |
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Dorsal lip |
-cells in frogs are inducer cells that control blastopore formation |
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Gastrulation in Birds and reptiles |
-modified by distribution of yolk -portion of cytoplasm that divides to give rise to primary tissues of the embryo is confined to small surface of egg -cleavage produces a disclike layer of cells at the surface of the yolk called the Blastodisc |
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Blastodisc |
- cells of the blastodisc then separate into two layers called the epiblast and hypoblast -cavity between them is called the blastocoel -gastrulation occurs when epiblast top layer, streams toward the midline of the blastodisc, thickening epiblast |
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Primitive layer |
- thickened layer of epiblast -begins forming in the posterior end of the embryo and extend toward the anterior end -initially designates the future posterior end of the embryo, and when fully elongated it will become dorsal side of embryo with ventral side below -as it forms, midline sinks forming a Primitive groove |
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Primitive groove |
-conduit for migrating cells to move into the blasteocel -first cells to migrate are epiblast cell, which will form the endoderm -cells migrating laterally between epiblast and endoderm form mesoderm - epiblast cells left at the surface of the blastodisc form the ectoderm. -all three layers of the chick embryo arise from epiblast |
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Hypoblast |
-bottom layer -only a few near posterior end contribute to embryo, forming germ cells that later in development migrate to developing gonads |
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Extraembryonic membranes |
-each primary tissue layer extends forming 4 extramembryonic membranes -conduct nutrients from the yolk to the embryo - store metabolic wastes removed from the embryo |
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Yolk sac |
- consists of extension of mesoderm and endoderm that enclose the yolk -remains connected to the gut of the embryo by the stalk -yolk is absorbed by blood vessels in the membrane, which transport nutrients to embryo |
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Chorion |
-produced from ectoderm and mesoderm -outermost membrane -surrounds embryo and yolk sac -lines outside of egg shell -exhanges oxygen and carbon dioxide with the environment through the shell of the egg -carbon dioxide is delivered by circa system to chorion and it then picks up the oxygen that is absorbed through shell and chorion. |
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Amnion |
-innermost membrane -closes over embryo to form amniotic cavity. -cells secrete, amniotic fluid, into cavity, which bathes the embryo and provides an aquatic environment for it to develop -made fully terrestrial vertebrates possible |
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Allantois |
-sac formed from a membrane derived from mesoderm and endoderm that has bulged outward from gut -this sac lines the chorion and fills space of chorion and yolk sac. -stores nitrogenous wastes (uric acid) removed from embryo -part that lines chorion forms a rich bed of blood capillaries that is connected to embryo by artery and veins |
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Organogenesis |
-process by which the ectoderm, mesoderm and endoerm develop into organs -gives rise to individual with body organization characteristic to species. -involves same mech as gastrulation: cell division, migration, selective cell adhesion, induction, and differentiation plus an additional apoptosis |
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apoptosis |
-certain cells are programmed to die |
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ectoderm |
-nervous system develops -organogenesis beings with neuralation: development of nervous system from ectoderm |
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Notochord |
-mesoderm -preliminary to neurlation, cells of the dorsal mesoderm form the notochord -a solid rod of tissue that extends the length of the embryo under the dorsal ectoderm |
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Neural plate |
-dorsal mesoderm cells under the ectoderm induce the ectoderm cells above them to thicken and flatten into longitudinal band called neural plate - neural plate sinks downward along midline (2), creating deep groove -edges elevate along the sides of the neural plate -as groove becomes deeper edges move together |
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Neural tube |
-edges of neural plate come together over the center of the groove to form the neural tube -neural tube runs the length of the embryo -neural tube then pinches off from overly ectoderm -ectoderm that comprises the neural tube -the neural tube develops into the central nervous system, brain and spinal cord |
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Neural crest |
-region where neural tube pinches off from ectoderm -ectoderm cells, that migrate to many other locations in developing embryo to become numerous types of cells and organs -one of the defining features of vertebrates. -can develop into cranial nerves of head, bones of inner ear and skull, carriage of facial structures, and teeth -others form ganglia of the autonomic nervous system, peripheral nerves leading spinal cord to body, and nerves of developing gut -also move to skin where they form pigment cells and to adrenal glands where they form medulla of kidney |
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Somites |
-while neural tube is forming, mesoderm separates into block of cells called somites -spaced one after another along both sides of notochord -give rise to vertebral column, the ribs, the repeating sets of muscles associated with ribs, muscles and limbs |
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Mesoderm outside somites |
extends around primitive gut (lateral mesoderm) -splits into 2 layers, one covering space of gut and the other lining the body wall. -space between layers is coelom of adult |
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Eye development |
-develop by same pathway in all vert. -brain forms at anterior end of neural tube 1. one paired set of vesicles, optic vesicles, develop into the eyes |
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Optical vesicles |
- derived from specific region of neural ectoderm in the neural plate - expression of TF pax6, six3, and Rx1 in the most anterior tip of the neural plate is responsible for optic vesivle development -they grow outward and contact the overlying surface ectoderm, where they induce a series of developmental responses in both tissues |
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optical vesicle outer suface |
- thickens and flattens at the region of contact and then pushes inward transforming optic vesicle into a double walled optic cup, which eventually become retina |
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optic cup |
-becomes retina - induces surface ectoderm to thick in into dislike swelling, lens placode, which invaginated toward the optic cup, and its edges fuse together to form lens vesicle |
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lens vesicle |
-covered in ectoderm, which detaches from from surface ectoderm - lens vesicle become the developing lens -the cells being to synthesize crystallines, transparent lens specific proteins that collect in deposits -lens cells then lose nuclei and form elastic clear lens - |
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Lens |
-as developing lens invaginates, it induces overlying surface ectoderm to begin differentiation into the Cornea -overlying ectoderm secretes layers of collagen -neural crest cells migrate into collagen layers and form new layers of cells that mature into cornea -TF pax 6 is important for development of cornea |
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Eye development |
-demonstrates differentiation -ectoderm cells that are induced to form lens of eye synthesize crystallines, where in other locations they typically synthesize kertain |
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Embryonic development of humans and mammals |
see below |
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placenta |
-in uterus, embryo is nourished by placenta, which provides oxygen and nutrients and carries away carbon dioxide and nitrogenous wastes |
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Pregnancy or gestation |
- longer in larger animals -in humans, 38 weeks -divided into 3 trimesters (each 3 months long) |
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first trimester |
- cleavage, gastrulation, and organogenesis take place -by 4th week heart is beating -8th week major organs have formed and it is called Fetus |
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Cleavage and Implantation |
-after fertilization cleavage divisions take place during passage of embryo down oviduct -by day 4 Morula, ( 16-32 cell) produced and endometrium is ready for implantation -7 days after ovulation, blastocyst is formed, a single layered hollow ball this is 70-100 cells, with a fluid filled cavity called the blastocoel |
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Blastocoel |
-fluid filled cavity, with dense mass of cells located to one side called inner cell mass. inner cell mass- gives rise to embryo as well as the yolk sac, the allantois and the amnion -outer layer gives rise to trophoblast -when blastocyst has increase to appropriate size it breaks out from zona pellucida and sticks to endometrium on the side with the inner cell mass |
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Implantation |
-begins when the trophoblast, secretes proteases that digest pathways between the endometrial cells |
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Inner cell mass |
-of burrowing blastocyst separates into embryonic dis, with two distinct cell layers epiblast- layer father from blastocoel hypoblast- nearer the blastocoel, which give rise to extraembryonic membranes |
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Gastrulation |
-proceeds with formation of primitive streak in the epiblast. Some epiblast cells remain in place becoming ectoderm while others enter streak to form endoderm and mesoderm. Endoderm- folds to form primitive gut and becomes surrounded by ectoderm and mesoderm Neurlation takes place as in birds |
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Amnion |
- layer of epidermal cells forming roof become amnion -amnion expands until it surround embryo and suspends it in amniotic fluid |
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yolk sac |
-in birds formed by hypoblast -in mammals, the mesoderm of the yolk sac gives rise to blood vessels in the embryonic portion of placenta |
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Chorion |
-trophoblast cells grow rapidly around the embryo and amnion to form the chorion -then a connecting stalk forms between embryonic disc and chorion, while chorion begins to grow into endometrium as fingerlike projections called chronic villi -as chorion develops mesodermal cells of yolk sac grow into it and form a rich network of blood vessels, the embryonic cirulcatio of the placenta |
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Placenta |
-formed where villi occur - in humans apes, monkeys and rodents, maternal blood bathes tropoblast layers of placenta - the fetal capillaries are positioned next to the trophoblast so that two cell layers separate material and fetal blood -but embryonic circulation remains closed - oxygen passed to embryo and well as alcohol, caffeine dugs and toxins in cigarette smoke -carbon dioxide and nitrogenous wastes pass from embryo to mother and are disposed by mothers lungs and kidneys |
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Umbilical cord |
- as embryonic blood circulation continues, the connecting stalk between the embryo and placenta develops into umbilical cord - a long tissue with blood vessels linking the embryo and placenta -vessels are derived from allantois |
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Pharynegeal arches |
-by end of 4th week -embryonic features of all vertebrates -contribute to formation of the face, neck, mouth, larynx and pharynx. -16 week, bone and tissues form producing skeleton |
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Estrogen |
-as fetal growth comes to close, estrogen is secreted by placenta at the time causing cells of uterus to express gene for receptor of hormone oxytocin |
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Oxytocin |
-secreted by pituitary gland -binds to its receptor, triggering smooth muscle cells of uterine wall and to begin contractions of labor, marking the beginning of Parturition-three stage process of giving birth -postive feedback during birth |
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1st stage of labor |
contractions push fetus close to cervix -in response to cervix dilation, stretch receptors in the wall send nerve signals to hypothalamus which stimulate pituitary to secrete more oxytocin |
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2nd stage of labor |
-birth of baby -contraction push baby through cervix, in vagina and at this point stretch receptors in vagina trigger contractions of abdominal wall that increases using of baby through birth canal |
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3rd stage |
continuing contractions of uterus expel the placenta, and remnant of umblicaial cord and embryonic membranes |
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Estrogen and progesterone |
-before birth stimulate growth of mammary glands in mothers breasts -high levels prevent glands from responding to prolactin |
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prolactin |
- a pituitary hormone that simulates gland to produce milk -after birth, levels of estrogen and progesterone fall and prolactin increases, causing milk production -secretion of milk is stimulated by oxytocin and prolactin |
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Gonads |
-develop during 4 week of gestation |
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Y chromosome |
determines whether biopotential gonads and internal ducts develop into male or female gonags |
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SRY |
sex determining region of y becomes active during 7th week -protein causes molecular switch of primitive gonads to develop into testes fetal testes secrete two hormones 1. testosterone 2. AMH - no SRY, then primitive gonads under influence of estrogen's and progesterone secreted by placenta, develop into ovaries -Mullerian ducts develop into oviducts |
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testosterone |
- stimulates development of Wollfian ducts into male reproductive tract including epididymis and vas deferens |
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AMH |
- causes mullein ducts to degenerate or disappear |
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microtubules |
- changes cell shape and produces whole cell migrations -powdered by dynes and kinesins |
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microfilaments |
- power whole cell migrations -powered by myosin |
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fribronectin |
-a fibrous, elongated glycoproteins of the ECM that routes cells along paths -needed for gastrulation and I'm mammals mesoderm and neural tube development does not occur without |
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cell adhesion molecules (CAM) |
membrane proteins that mediate cell adhesion class: Cadherins -play critical roles in maintaining connections and organization of cells |
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Integrins |
- receptor proteins that span the plasma membrane -produced by neural cells -communicate changes in ECM to cytoskeleton |
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apoptosis |
1. cell shrinkage 2. deflation of chromatin 3. blebbing 4. phacotcytosis of whole cell by macrophages |
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CED4 |
active form, required to activate CED 3, which is a protease of Classe of proteases and camasses |
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CED 3 |
activated CED 3 capase is needed to turn on cell death program -in absence, CED9 inactivated CED 4 which cannot activate CED 3 so no apoptosis occurs. |
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CED 9 |
-has to be inactive for CED4 to bind to CED 3 protease |
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bone morphogenic proteins.(BMP) |
- death signal trigger apoptosis events that result in removal of tissue between digits in birds |
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Gremlin |
protein that inhibits BMP, which will result in webbed feet -also involved in wing of bats, webbing of digits of forefeet |
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miRNA |
-involved in apoptosis -negatively regulated red 4 homolog |
