User talk:Z3372824

From Embryology

• Some cells live just a day, liver 1 month etc. variable time • 2 copies in genome (us) crossing over occurs in gametes. Following s phase: 4 copies of every chrom. Duplication to get 2 daughter cells.

• G1- GROWING IN VOLUME. Most variable time in life. Check point: division of cell okay? Screening: bad: won’t copy genome, stops uncontrolled cell replication • G0: leaves cell cycle that cant divide again. E.g. Satellite cells (transiently there) • S Phase: (before mitosis) duplication of genome. Check point 2: copy of chromosome okay? No= stops cell dividing. If checkpoint goes bad: cancer e.g. p53. • G2: gets cell ready to divide (mitosis entry: so stock up on ATP) In mitosis no gene expression! Cant make new energy. (short prd of time) • 5 stages of mitosis: prophase, prometa, meta, ana, tela (defined by nucleus underlying mitosis) 2. Disassemble cytoskeleton. Microtubules form spindle only during mitosis: transport vesicles, nucleus) NO ROADWAY: so no exocytosis, endosytosis • Cytokinesis: division of cytoplasm. Overlaps with telophase. Microfilament (actin filaments) acts as belt, cuts into 2. • Meiosis diff to Mitosis : does it twice: but no duplication again: so get haploid. Crossing over. No duplication. Recombination occurs. Only 1 copy of every chromosome. Only in germ cells. Recomb : prophase 1. Indep assortment of chromosomes in meiosis 1. Progeny diff not identical.

• Female gametogenesis occurs in embryo. Oogenesis. Normally puberty: 12-13. All arrested at meiosis 1. Only complete meiosis 1 once oocyte released. (grafted follicle only, other follicles don’t complete it). Ovulated oocyte doesn’t complete meiosis 2 unless its fertilised. When it does, get a second polar body. Possible: 1st polar body also undergoes meiosis 2 then get 3 polar body. No point. • Meiosis 1 = major cause of Down’s. 1 chromosome gets left behind on spindle apparatus = 3 chrom 21’s. Instance increase with age. Aneuploidy= abnormal number of chrom. Meiosis safest when it occurs quickest, age increase, resources decrease. More env. exposure. • Male: diploid spermatogonia in testes. Around periphery of seminiferous tubule. Undergo mitosis before meiosis ( to replace itself coz it’s a stem cell). Setoli cells: support to spermatozoa. Its junctions form blood-testes barrier. • Primary spermatocyte : meiosis 1. Secondary spermatocute: meisos 2 ( cant see it coz it does it so quickly) Spermatid: round, haploid cell that’s completed meiosis, but hasn’t completed everything yet in development? Cytokinesis not completed! All progeny joing by cyto bridges? UNLIKE FEMALE 2 with x chromosomes, 2 with y. • Oocyte takes years, male takes 44 days? • Cortex thicker in infant (only primordial follicles), than older. Get germinal epithelium then cortex then medulla? Stromal cells (tiny dots?) • Medulla: large maternal blood vessels. Not many primordial oocyes here. • HUGEEE variability in number of NGF’S (oocytes) lose it by apoptosis (atresia) • Ovary lies within peritoneal cavity. Oocyte increases in volume, 4 hormones released.

• hcG synthesised by syn/blsat. Local secretion. Taken up by maternal blood through lacunae. Preserves the corpus luteum- makes progesterone which maintains uterus in secretory phase. • Placenta takes over (after placentation, get the endocrine role of placenta function) e.g. estrogen and progesterone. • Extravillous syto.blast. mixed in with maternal stroma and surround ? • Epiblast and hypoblast = week 2. Presence of endometrial to dissidual cells = indicates pregnancy. • Endometrial glands secrete onto surface, empty into lacunae (has maternal blood and endometrial glands) • Chorionic cavity= largest space. Forms placenta (chorion frondosum- week 3), few villi. Other side has a lot of villus(mothers vessels) • Conceptus: embryo and extraembryonic apparatus. • Decidua b. maternal contribution. • Decidualisation occurs over entire uterus.


• Muscle: striated mm. aren’t smooth mm., as there aren’t sarcomeres within them. However, include actin, myosin etc. • Ex/for Intramembranous ossification (in embryo have endochondral ossification-cartilage) • Ist skeleton= cartilage./ degenerates and replaced by bone. (ex/for joint cartilage of bone) • Sk. Mm. forms by same process for all types of skeletal mm. • All sk/mm originated from somites (mesoderm) which migrate into anatomical location • Somites form r/c (head to tail) • Differentiates dorsolaterally (sclerotome- receives signals from spinal cord). Dermomyotome closer to ectoderm. • Somite disperses and spreads/ 2 sclerotomes together contribute half of skel. • Vertebra= cartilage/ ossifies (primary oss.) 1st element = centre. • Dorsal portion forms dermis. (dermatome) ventral migration of dermis around body wall into limb bud. Maintains segmental pattern. Forms connective tissue/not bone or cartilage. • Myotome are precursor cells to muscle cells. NONE of these cells are mm cells. Spreads dorsally like dermatome. • Epaxial mm are from dorsally migrating myotome. • Hypaxial mm. form 3 mm layers of body walls. (interc.) Migrates into limb bud • Form flexors (ventral) and extensors (dorsal) • MM. Position themselves adjacent to cartilage • Diff to form myoblasts. (precursor) then proliferate at mm site. Under effect of growth factors. • Critical mass= depleting growth factor levels. Therefore, plasma membrane of adjacent myoblasts fuse together (unique) = multinucleated/ but no contractility. = Myotube • Don’t extend laterally but end to end • 1st = primary myotubes (not all myoblasts fuse/ they’re in the surrounding) • Differentiates/ get sarcomeres = myofibres • (not complete) quantity is not maximal. • Primary fibres , motor neurons attract to its growth factors.. (motor neuron will branch out) • Secondary myof/ adjacent fibres • Form motor unit collectively. • Mm fibres differentially/ postnatally • Pattern of innervation determines quantity.




• Meso diff into cartilage = chondro. Centre. • Overt diff. = tissue you want. • Primary ossif. Centre = bands of bone formation (cartilage) dying chondroblast releases VEGF = stimulates BV growth. To this region. Brings osteoblasts to this site. Bone is highly vascular. • Head region = second ossification centre. Also brings osteoblasts • Ongoing process = postnatally. • Notochord may form part of nucleuspulposis. • Remodelling of bone by osteoclasts/ from Haemopoeitic stem cells lying on fibrous layers covering bone. • Intramem. Ossification. Base of skull forms by endochondral ossification. (base initially is cartilaginous ossification) not completed coz brains needs to grow. Therefore there needs to be a reserve of cartilage for growth. • Ventral portion of cartilage remains as cartilage e.g. nasal septum. • Cranial vault = intramemb. Except sutures / mesenchyme which don’t ossify (to expland/pass through birth canal)


Uploading Images in 5 Easy Steps  
First Read the help page Images and Copyright Tutorial.
Hint - This exercise is best done by using separate tabs on your browser so that you can keep all the relevant pages easily available. You can also use your own discussion page to copy and paste links, text. PMIDs etc that you will need in this process.
  1. Find an image .
    1. Search PubMed using an appropriate search term. Note that there is a special library of complete (full online) article and review texts called PubMed Central (PMC). Be very careful, while some of these PMC papers allow reuse, not all do and to add the reference link to your image you will still need to use the PMID.
    2. You can also make your own search term. In this link example PMC is searched for images related to "embryo+implantation" http://www.ncbi.nlm.nih.gov/pmc/?term=embryo+implantation&report=imagesdocsum. simply replace "embryo+implantation" with your own search term, but remember not everything in PMC can be reused, you will still need to find the "copyright notice" on the full paper, no notice, no reuse.
    3. Where else can I look? BioMed Central is a separate online database of journals that allow reuse of article content. Also look at the local page Journals that provides additional resources.
    4. You have found an image, go to step 2.
  2. Check the Copyright. I cannot emphasise enough the importance of this second step.
    1. The rule is unless there is an obvious copyright statement that clearly allows reuse (there are several different kinds of copyright, some do not) located in the article or on the article page, move on and find another resource. Not complying with this is a serious academic infringement equivalent to plagiarism."Plagiarism at UNSW is defined as using the words or ideas of others and passing them off as your own." (extract from UNSW statement on Academic Honesty and Plagiarism)
    2. You have found the statement and it allows reuse, go to step 3.
  3. Downloading your image.
    1. Download the image to your own computer. Either use the download image on the page or right click the image.
    2. To find the downloaded image you may have to look in your computer downloads folder, or the default location for downloaded files.
    3. The image file will have its own original name, that you will not be using on the wiki. You can rename it now (see renaming below), but you should also make a note of the original name.
    4. Make sure you have everything ready then for the
    5. You have the image file on your computer, go to step 4.
  4. Uploading your image.
    1. First make sure you have all the information you want to use with the file readily available. There is also a detailed description below.
    2. Towards the bottom of the lefthand menuunder “Toolbox” click Upload file. This will open a new window.
    3. In the top window "Source file", click "Choose file" and then navigate to find the file on the computer. and select the image.
    4. If you have done this correctly the upload window will now have your image file shown in choose file and also in the lower window "File description" in "Destination filename:" DO NOT CLICK UPLOAD FILE YET.
    5. Rename your file in "Destination filename:" this should be a brief filename that describes the image. Not any of the following - the original file name, image, file, my image, your ZID, etc. Many of the common embryology names may have already been used, but you can add a number (01, 02, 03, etc) or the PMID number to the filename to make it unique.
    6. If the filename or image has already been used or exists it will be shown on the upload page. If another student has already uploaded that image you will have to find another file. Duplicated images will not receive a mark, so check before you upload as you cannot delete images.
    7. In the "Summary" window for now just paste the PMID. You will come back and edit this information.
    8. Now click "Upload image" at the bottom of the window, go to step 4.
  5. Edit and Add to your page.
    1. Edit - Open the image with the "Edit" tab at the top of its page. You should see the PMID you had pasted earlier in the new edit window. Add the following information to the summary box.
      1. Image Title as a sub-heading. Under this title add the original figure legend or your own description of the image.
      2. Image Reference sub-sub-heading. Use the PMID link method shown in Lab 1 and you can also have a direct link to the original Journal article.
      3. Image Copyright sub-sub-heading. Add the copyright information under this sub-sub-heading exactly as shown in the original paper.
      4. Student Image template, as shown here {{Template:Student Image}} to show that it is a student uploaded image.
    2. Add - Now add your image to your own page under a subheading for Lab 2 Assessment including a description and a reference link. If still stuck with this last step, look at the example on the Test Student page.
    3. Done!

Students cannot delete images once uploaded. You will need to email me with the full image name and request deletion, that I am happy to do with no penalty if done before I assess.

Non-Table version of this page

Stress Relief....