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Introductory Biology II: Embryology
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- 1End result of spermatogenesisfour non-identical sperm cells produced
- 2End result of oogenesis1 large ovum produced and 3 non-functional polar bodies
- 3Fertilizationoocyte undergoes meiosis, sperm cell fuses with ovum to form a zygote
- 4Cleavagelots of RAPID cell divisions in zygote, very little growth or transcription, reduction of cytoplasmic volume, axes form
- 5Blastulahollow ball of cells resulting from cleavage
- 6Gastrulationmake 3 distinct "germ" layers (endoderm, mesoderm, ectoderm) in Blastula, results in primitive gut formation
- 7Gastrula3 layered embryo
- 8ectodermforms nervous system and outer layers of skin
- 9endodermforms digestive tract. respiratory tract, and digestive organs
- 10mesodermforms kidneys, heart, muscles, bones
- 11Animal pole vs vegetal poleAnimal pole divides faster; dark brown coloring in Xenopus laevis; later are the ectoderm axis
- 12Cell movements during gastrulationa lo of cells rush in from the outside and the rest spread themselves out (epiboly) thinly in an stretched out layer
- 13Molecular basis of gastrulationchanges in cell adhesion
- 14fate mapstracking cells in time and space; show where each tissues of germ layer originally came from; do NOT inform us about when states of cell determination occur
- 15Roux's experimentexperimented by killing one frog blastomere cell at two cell-stage and observing the other's development
concluded that blastomeres at the earliest stage have a predetermined fate and only a half embryo can form - 16Driesch's experimentseparated sea urchin cells at two-cell stage and observed growth of a small but otherwise normal larvae
revealed that at two (and four) cell stages, individual blastomeres are totipotent - 17totipotencythe capacity for a cell to give rise to any embryonic cell type
- 18Horstadius' tier experimentsseparate cells at 8 cell stage --> get a ciliated blastula and a vegetalized blob
reveals how cells lose totipotency and become committed to a developmental fate as development proceeds - 19John Gurdon's experimentstake adult frog skin cell and tadpole gut epithelial cell, destroy nuclei, and transfer nucleus into unfertilized eggs --> tadpoles develop
shows that genetic information is not lost as cells differentiate - 20Regulative Development Modelearly embryos have a capacity for regulation; have developmental plasticity
- 21Asymmetric DivisionSister cells can be born differently despite having the same genetic information
- 22Symmetric DivisionSister cells with the same genetic information become different as a result of different neighbors acting on them
- 23How do cells know which genes to express?the combination of internal information from asymmetrical distribution & external information from cell-cell signaling
- 24How animal-vegetal axis is determined (in Xenopus)Determined maternally; egg radially symmetric before fertilization & there is differential localization of maternal mRNAs
- 25How dorsal ventral axis is determined (in Xenopus)determined by where the sperm enters --> makes the cortex rotate 30 degrees
- 26Inductioncell-cell interactions cause special tissues to develop
- 27Spemann's separation experimentdivided two cells with a baby hair, one half could grow own embryo BUT plane of division is crucial
- 28The Organizercluster of cells in developing amphibian embryo that induce development of central nervous system; crucial discovery to concept of induction
- 29dorsal lip of the blastoporecells that are COMMITTED to invaginate into the blastula, "the Spemann organizer," formed by the gray crescent region of an egg
- 30Results of dorsal lip transplantcontinued to be committed to its "fate" --> initiated a second gastrulation in surrounding tissue and two embryos/axes form via induction
- 31B-cateninprotein that can induce changes in cell fates based on where it accumulates; can form new dorsal regions when injected
- 32Specificationwhen the mesoderm is under the ectoderm, tissue is specified to become the nervous system BUT if moved it could become something else
NOT irreversible! - 33Determinationwhen cells will produce the determined cell types and will not be altered by inducers to become completely different
IRREVERSIBLE - 34Involuting Marginal Zone cellson the dorsal lip of the blastopore in developing Xenopus eggs, move to the interior via invagination and become the mesoderm
- 35NeurulaWhat the embryo is called after gastrulation leads to the formation of the neural fold --> notochord
- 36What's in a human sperm cell?Haploid nucleus, centriole (forms spindles during division), mitochondria, acrosome enzymes (to digest egg coat)
- 37What's in a human egg cell?Egg cytoplasm: nutritive proteins, ribosomes & tRNA, **mRNAs**, morphogenetic factors, protective chemicals, egg cortex (cortical granules)
Vitelline membrane to attract and activate sperm + regulate ion flow - 38Egg-sperm recognitionExocytosis of sperm's acrosomal vesicle, bindin coats sperm actin filaments and binds sperm to vitelline envelope, sperm passes through and membranes fuse
- 39Fast block to polyspermyDepolarization of egg electric potential due to influx of Na+ means no more sperm can fuse
- 40Slow block to polyspermycortical granules cleave links between vitelline membrane and plasma membrane, stimulated by increase in intracellular Ca2+ from sperm fusion
- 41Follicle Stimulating Hormone (FSH)produced by pituitary gland, controls production of oocytes in women and sperm in men; stimulates production of estrogen in women
- 42Corpus luteuminvolved in production of progesterone, left behind after egg leaves in ovulation, maintains uterine lining (endometrium)
- 43Luteinizing hormonehormone that triggers ovulation and development of corpus luteum
- 44where does fertilization (as well as the first cleavage) occur?in the fallopian tube/OVIDUCT
- 45first ball of cells after cleavage in humansthe morula
- 46human chorionic gonadotrophin (hCG)hormone secreted by specialized cells that maintains the corpus luteum after implantation
- 47Implantationhuman blastula is implanted into endometrium, trophoblast outer layer forms placenta so direct nutrient exchange can occur
- 48chorionic gonadotropinhormone secreted by trophoblast and chorion that maintains corpus luteum after implantation
- 49The Four Extra-embryonic Membranes1) Chorion
2) Amnion
3) Yolk Sac
4) Allantois - 50Choriontrophoblast, surrounds everything
- 51Amnioncushions embryo and prevents desiccation; is fluid filled
- 52Yolk sacforms blood cells that migrate into the embryo, doesn't actually contain yolk
- 53Allantoisdevelops from archenteron (gut) outgrowth, becomes a part of the umbilical cord
- 54First Trimesterthree germ layers --> limb buds --> developed enough to be called an embryo (non-self) --> limb elongation --> organs are in place --> hCG levels drop and CL begins to disentegrate
- 55Second Trimesterprogesterone production --> general growth --> bone development --> heart beating --> vernix (skin) covering
- 56Third trimesterweight increase --> eyelids split --> lungs mature --> hearing develops --> uterine cavity full
Información
- Descripción
- Embryology
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- Usuario eliminado · abr 2020
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- 7 abr 2020
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- Creado por Candice Young · 8 ago 2017
- Copiado por Gabriel Kofi · 7 abr 2020
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