Embryology PDF

both derived from Monozygotic Twins a single fertilized...

both derived from Monozygotic Twins a single fertilized egg - - always same Sex Splitting at 2-cell occurs - Zygote - rarest form 1 : 258 Stage 12 amnions Separate , chorions , and placent as splitting yesa late Splitting in blastocyt two One ICM early common amnion Yields two ICMs , Separate amnions chorion and placenta common chorions and placent as fertilizations Dizygotic Twins-develop from separate Two released from ovaries more common 1 : 89 eggs - diet rich in pytoestrogens - Each fertilized by separate sperm induce bilateral egg Ovulations - rate due to gone up Fertility - Each in embryo implants womb separately treatments - same sex or different Separate placentas and separate inner sacs Multiple Twins-conseq of hormonal induction , or implantation of multiple embryos during IVF -naturally occuring as well Vanishing Twins - Intense competition between fetuses (one fetus takes most of = the resources and leaves the other fetus with little to no resource - most common form of twins vanishing twin' is then reabsorbed pancaked to the of - edge or the amniotic - sac first trimester Chimerism single organism forms comprising cells of more than one distinct genotype. be formed fusion of embryos of ; experimental naturally by either : cells or exchange - can manipulation Quail Chick Mouse Mix and Match Experiments : + combine two diff cell types ; Stick tog - - chimeric Mouse  Profound Chimerism Ex Lydia. Fairchild transfusion imp blood problems transplant and transfusion engraftment , in - rare , rape blood cases , doping Microchimerism Coexistence of Fetal maternal in organism and cell lines the same Alzheimer's i s Study Y-containing cells (male) in female brain - Bi-direction fetus trans-placental trafficking between - mother - Mother / fetus formly thought to be placental blood barrier impermeable turns - - out leaky to stem Cells of stem cells exchange - load 3-4 kids optimal cell - Lumaquires stem cells from mother Birthing hard SC's Mothers from : on mother - recovery pick up stem cells recuperation her hosted Stem cells - own mother who male later children left in residence former inhabitants of pick by the · can stem cells womb up (elder Siblings) Ex. Mother born n elder brother's stem cells all offspring - - fetus that later miscarried fetus that aborted - was PROTECTION AGAINST SOME DISEASES Ex lupus. mothers suseptible genotypic allele - Fathers resistant allele > - resistant allele fetus colonize mother ; produce circu blood SC - marrow or that carry the to Fathers resistant to mothers mated slightly developing lupus resistant - > - more allele paternal  Stem Cells differentiale cells w capacity to into other cell types Ex hematopoietic cells in bone iPSC SC Ertilized marrow , , cancer , embryo/ zygote Potency - range of possibilities to differentiale into # of the Se differentiale greater potency greater cell types can = Categories of Stem Cells Totipotent totally = become all within that potential cell organism - and most can types first cells of have this an embryo potency - Pluripotent = plenfully not placent a give rise to cell type within an organism (Not extra-embryonic structures) - any placenta or - iPSC differentiale into cell lineage - any Multipotent multiplayer (can be any player limited to a game-lineage) = less potency - to restricted certain lineage - a Ex hematopoietic Stem RBC , granulocytes, - cells lymphocytes , -. or macrophages Unipotent = 1 lineage least potency - single lineage - - Ex orgonia. and spermatogonia Constraints Canalization Confining differentiation to single path a - Niche - constraining microenvironments (Ex pH temp). , Teratocarcinoma - derived from mouse male PGCs (early stage stem cell to sperm) - tumours contain bits of hair , follicle , tooth smooth muscle Shin intestine , , , transplanted between immuno-compromised mice (nucle mice : inbred line) -  transfered - cultured Cells can be to mouse hosts - TUMOUR GROWS ES cells in culture cells normally act ↓ EScellsinjeea ES cells injected under the shin of adult mouse normal blastocyt ↓ ↓ mouse develops Chimeric Mouse terocarcinoma develops normally THE CONTEXT A CELL IS PLACED IN HELPS TO DETERMINE ITS DIFFERENTIATION FUTURE Challenge Don't want tumour to wrong cell type or a develop 1. Constraints e canalization 3 Scaffolds decellularized (organs or tissues) treated io detergent to hill and remove ELM cells leaving only the dog bladders success -. 2 No tumours. 3 ? Transgenic iPSCs genetically modified humans long term effects - Waddington - Epigenetic Landscape hard to differentiation to Stem Cell - reverse - once committed hard to alter fate ,  Morphogens - diffusible substance which distributes in a varied manner to endow different locations with different concentration values. establishes > - which receive specific ques and can differentiale accordingly - cells a map Slime Mold responds to Cue (diffusing(Amp) to migrate together to form - slug. a Sing forms a stalk and fruiting body - Chemotactic Stimulated Secreted - CAMP movement by Starring Cells ↓ CAMP Secreted ↓ ↓ degredated by adjacent cells phosphodiesterase Secrele CAMP ↓ (Free (a2t) From Slug d eats mores , d rest forms a Stalk and fruiting body gives off spores Belousor Inabotinsky Reaction - model Kreb cycle with the mix of 2 chemicals - add indicator test tube oscillated between colours pH - - zhabotinshy refined and repeated experiment, fattened into Petri dish - highly ordered - a of seen waves colour change Reaction Diffusion Models Activator - (locally centred) Stimulates production of inhibitor fast Inhibitor diffusing turns off production of activator and stimulus -  Lewis Wolpert French Flag Model if tissue from a peice of transplanted one region of an embryo to another retains its of but differentiales to its identity origin according new positional instructions. Each the to cell has potential develop as blue , while or , red ↓ Position of each cell is defined the of by concentration morphogen h Positional differentiate to form values is interpreted by the cells which a pattern Planaria small centrally located pocket (gut to secrete enzymes and absorb nutrients) - - MASTER'S OF REGENERATION head tail morphogen vs -. Cells at of amputation : plane experience positional discontinuity - proliferate - smooth the gradient - Cockroaches developmental - molts regenerate between molt - each graft easily crazy glue > - - Intercalary Regeneration positional discontinuity - cells proliferate - increased of mass cells reconstitutes gradient - directs differentiation gradient - cell pathways two values juxtaposed Smoothing occurs - > - intercalation - shortest occurs by roule  Flowers flowers from meristem emerge apical. - Morphogen gradients act bud of to activate downstream patterning genes- - cell upon MADS transcription factors MADS Genes Morphogens ↓ MADS (TF) ↓ Activate genes (development) other MADS B of flower A expression petals - + - MADS B+ C to stamen (male rep organs) - - MADSC > - carpel (female rep organs)  Aristotle Fathere sperm Mother > - clot hint of early stage embryos display no gender - cloacal slit (vagina opening) - in slit Sutures and phallus forms - males up Males form of human ? more highly developed Lucretius forceful , male contribution goal-orientated - - Female accommodating contribution placid - - characteristic of influence if dominate quality and sex sperm clot > - determines gender - or Creationism : Spontaneous Generationism God to life from inanimate during intervenes spark - sex , matter material to build individual upon spark semen uterine and environment provide - Spallanzani hills microbes reanimate if sealed free of contaminated boiling cannot from supply air - , Louis Pasteur 1. Creationism from life doesn't animate i Spontaneous life starts spontaneously generation -. ii. Preformationism Creationism : Preformationism · Animalculists Preformationism all first · Ouists generations present in the gamete - Ex. dolls. 2 Epigenesis Preformationism 3 lookinsidaerson Ovists : is source egg Animalculists individual : Sperm carried the Epigenesis life from Fashion builds seed , gradual - gradually sperm , egg in  Preformationism : Ouists MBH Malpigni Chicks - folds early develop. observed hearts - Neural , embryo starts simple and then gets complex - not looking at embryos early enough - artifically fertilize insect by bathing them with Fertilizing fund of but - male saw the egg unseminated remained infertile eggs Bonnet hydra regeneration. - aphids which display asexual clonal ,Female reproduction parthenogenesis - sperm may not necessarily be required - Harvey - "Ex oro omnia" from comes all egg - Preformationism : Animal culists VH Van Leeuwenhoek in of saw sperm ejaculate executed prisoner who had syphilis - thought motile parasites that caused syphilis - sperm were Hartsoeher homunculus" in imagined person" the head of the sperm - a the Female and the inside the thought sperm unites with animal cule becomes - egg sperm One with the female the egg and Epigenesis SNPP/DV Spallanzani newt limb regeneration - - amplexus - females shed and the males release sperm in the form of semen eggs shorts prevent fertilization collect semen - wax & ,  failed identify fertilization to that active agent and not a parasite. - in sperm was Wolff vital force enteeny propels development - - Pander 3 layers germinal ectoderm mesoderm endoderm - - and , , Ectoderm rise to shin and CNS gives , lens , Mesoderm rise to bone gives muscle , , and organs Endoderm to endothelium of gives rise organ linings such as gut Prevost/Dumas - Sterile males had immotile sperm viable males have motile sperm. - Von holliker : from cell theory Cells can arise other cells - only of seminiferous tubules pig testes cross-section Sperm not parasites but develop - are - incrementally Sperm and Egg Fuse Fol Hertwig and research in Echinoderms (starfish and sea urchins) - clear entering and eggs see sperm - are can egg Fol discovered filament between the joining sperm and - egg Chambers used fine needle to break filament glass - filament broke perferentially at the sperm end · Dan studied Sea urchins - filament from the cell's head grows Sperm - - ACROSOME REACTION  Gametogenesis of development gameles spores - ova Sperm , egg , pollen ,. ect - , Germ cells can derive from diverse tissues : Plants stem cell any - Insects , fish , nematodes , frogs : Pole freshly Plasm-specialized Cytoplasm localized to one pole of the egg , or fertilized embryo Pole cells cells that inherit that cytoplasm -. to rise to precursors primordial germs cells > - give gameles - Insects (Drosophila Stage 1 > - Laid Egg Newly Stage 2 - EarlyCleavage , Cluster of nuclei Stage 3 - Pole-cell formation , nuclei migrate to periphery Stage 4 -> Syncytial blastoderm , all the cleavage nuclei are contained within a common Cytoplasm Cellularization , contains Stage S -> = 6 000 indiv ,. cells Nematodes restricted line is lineage - germ Female and Fuse female male pronucleus and pronuclei - male P grannies receives to become only one cell granules germ Cell - included in P cell p granules are only -. become confined p-cell to lineage - Mouse Primordial Germ Cells from migrate outside developing body (posterior primitive streak) into developing body - form tube When gut begins to roll up to a  populate genital ridge - enclosed in testes or ovary - PGC's ↓ Posterior Primitive Streak ↓ Developing Body (gut) ↓ Genital Ridge d Ovary or iestes SC Spermatogenesis Spermatog onia - - germ diploid cells , Cells Poc spermatogonia (empty) undergo e - eventually meiose to UNIPOTENT produce Spermatogonia Spermatogenesis - serve as sem cells for immature germ cells spermatids - Primary Spermatocytes - orient to tip of head diploid cells - golgi and coalesce into acrosome - - derived from between that actin spermatogonia - globular nucleus and golgi replicate DNA and Mitochondria with tubulin meiosis Segregate towards tail undergo - and centrosome - Flagella grows Secondary Spermatocytes - - naploid cells off formed cytoplasm sloughed at end - - Of meiosis onset of meiosis - RA Testosterone Spermiogenesis yea 2 > -. transformation of ↓ spermatids - into full head developed tail sperm cells w , , neck FSH Mitosis Meiosis ( meiosis) A Spermatocytes Spermatics Spermatozoa - spermatogonia -> spermatogonia - Al > - Y HAPLOID (undifferentiated) (differentialed) (PGC) 1. testis 61 of embryo enters > - arrest in cell cycle. 2 after birth divide mitotically again diploid Spermatogonia > -. 3 Spermatogonia act as stem cells 4. Meiotic division I S. Meiotic division 2 > - Spermatids. 6 Spermatios differentiale into mature sperm  Structure of Spermatozoa 9 +2 of arrangement membrane Microtubules forms plasma · Centrosome I Flagella - - I Flagellum nucleus meiosis four - divided symmetrically - haploid cells forms from of acrosome golgi encapsulates some nucleus - , Mitochondria to - move down acrosome - G actin concentrates between membranes of acrosome and nucleus external head and interior memb of hold to stick to cumulous Sperm acrosome receptors - cells and/ or oocyte At Fertilization > - all internal components transferred to oocyte Mitochondria derive from degenerate Mitochondria in - all zygule oocyte - ↑ haploid Spermatozoa - Dynein - App dependent for essential fella movement cia - and Mutation immotility of Flagella also of cilia - Immotile sperm = sterility Immotile Cilia absence of bronchial tractoring of -> mucous lung infection - left-right assymetry issues - Sperm Maturation > Sperm through eliuymis makes motile - -  Maturation hormone mediated - form of epididymosomes (epigenetic miRNA) info Sperm endocytose in - Mammalian Sperm require further in female reproductive tract processing Capacitation destabilizes - acrosome ready to Fertilize on contact - ~ - Hyperactivation-induced by near oocyte environment 2P3 pellucida ligand - -> Zone - cumulous cells progesterone - Sperm Fagella amplitude freq increases be - and , sperm may chemotactic Pri Docytes arrest in b IST meiosis until puberty Oogenesis Ovulation : oocyte hormones to send in IST tube signal to PGCs multiply during migration -> enter ovary Secondant 0 te ↓ 2Np meiosis Mitotic of Forms divisions orgonia within primary oocyte > - ovary EwD Arrest in metaphase Meiosis arrested in of divison /- until prophase puberty Fertilization d : meiosis ends Adult : Further and develop. Of primary oocyte growth Orulation Secondary oocyte (first Arrest in 2ND metaphase of division of meiosis & polar body) : completion ↓ Until fertilized Fertilization : of division 2 of completion meiosis > - second polar body Patterns of Oogenesis Primary Diploid Oocyte Second Haploid Egg First Metaphase Metaphase First Meiotic Second Meiotic D X * x Division - - ② Division > - F & z Flatworms - Roundworms Insects Echinoderms Amphibians Mammals Fertilized Polar - bodies nutrients provides Oogenesis it Oogonia increases in size and maternal cells deposit goods - as grows Mitochondria · to the amplify 1000s RNA (MRNA MiRNA) · ,  Oogenesis i. Oogonia undergo mitotic division Orgonia 3 ii differentiale rise to giving primary oocyte PRENATAL iii. Primary oocytes enter meiosis arrested in prophase of first meiotic division POSTNATAL i. At or just before ovulation , primary oocyte completes first meiotic division giving rise to secondary first polar body and oocyte ii. Secondary oocyte enters second meiotic division but held in metaphase. 2 1 Fertilization does. not occur , secondary oocyte degenerates. Fertilization 2 second meiotic division rise to occurs , secondary oocyte completes giving an orum and a second polar body  · Proteins Cortical Granules histones enzymes , telomerases you granules Golgi - - , , periphery (cortex)of forms golgi vesicles that dispense to cell comical granules - - cortical contain · vitelline coat granules hyaline , glycosaminoglycans proteoglycans , , cross-link G actin accumulates in cortex under cortical plasma - membrane and around granules Oocyte starts to deposit external protective materials - vitelline coat and (glycoprotein) · zona pellucida jelly shell villi · albumen , , Undergoes asymmetric divisions 1-2 (1 big polar body) becomes ↑(1 big cell 2-3 - cell cell 1 polar - , , , bodies Haploid - in large oocyte cell Ovarian Context meiotically competent - meiotically incompetent 1 # control menstrual > - cycle - & L FSH Thecal Cells Stimulates follicles - E e estrogen-follicular development onthe O · - O ovanya > - for ovul. prep eggs Preantral Primary # D = Cumulus Cells - growth/development/ Early maturation of antral oocyte oocyte Order. ↑ Preovulatory ↓ 1. Cumulus Cells oocyte maturation. 2 Zona Pellucid a and orulation 3. Periviteline Space 4. Oocyte Fertilization Environment of female genitalia Cycle dependent pH - cycle tract area-dependent mucopolysaccharides (cervical mucous) - - and Mucopolysaccharides form fern like branching structure packing and density - alters - viscosity out and degree of barrier get here G-mucous-sticky block to - of dense , bacteria and spero , oser ↳ L-mucous traps ineffective - but stretchy mucous Sperm -