Week 1 Movie

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Summary of early development in the first week following fertilization

  • The conceptus proceeds through embryonic cell cycle rounds of mitosis still enclosed within the zona pellucida. Progressing from a zygote, to blastomeres, then to a morula and finally to a blastocyst.
  • The uterine tube epithelium consists of ciliated cells that are moving the secreted fluid towards the uterine body. The conceptus is floating "boat-like" within this fluid and moved in the same direction.
  • Towards the end of the first week the blastocyst has reached the uterine body and from about day 5 onwards, the blastocyst "hatches" from the surrounding zona pellucida.
  • The conceptus can now receive nutrition directly and can commence the process of implantation in week 2.


Week 1 Links: MP4 version | Quicktime version | Week 1 Overview Movie | Lecture - Week 1 and 2 Development | Week 1 | Blastocyst | Human Blastocyst Mitosis | Blastomere Mitosis Movie | Cell Division - Mitosis | Carnegie stage 3

Terms

  • blastocyst - the developmental stage following morula, as this stage matures, the zona pellucia is lost allowing the conceptus to adplant and then implant into the uterine wall.
  • blastomeres - the cells resulting from the initial rounds of mitotic division of the zygote. These cells become smaller (in cytoplasmic volume) with each division.
  • conceptus - the cellular structures all formed from the original zygote. This includes the embryo, the fetal placenta components and fetal membranes.
  • corona radiata - layer of follicle cells of cumulus oophorus remaining attached to zona pellucida of oocyte after ovulation.
  • infundibulum - funnel-shaped initial segment of uterine tube (oviduct or Fallopian tube) opening into peritoneal cavity and connected to the ampulla. The peritoneal opening sitting over the ovary.
  • inner cell mass - the clump of cells found inside the blastocyst. These cells will go in to form the embryo, these are the "stem cells" (we here about in the media) that are totipotential, they can form any tissue in the embryo. Mature oocyte-the female germ cell released at ovulation from the ovary.
  • ovulation - release of the oocyte from the mature follicle.
  • morula - (L. morus = mulberry) early stage of development (12-15 cells) Followed by formation of a cavity in the mass (blastocyst stage). (More? Week 1)
  • parental genomes - the male (sperm) and female (oocyte) DNA which contributes to the embryo's cells.
  • polar bodies - 3 exclusion bodies which contain the DNA not used by the embryo. Contributed to initially by the meiotic division of the oocyte.
  • pronuclei - the male (sperm) and female (oocyte) nuclei within the fertilized oocyte, prior to their combination to form the new embryo's nuclei.
  • trophoblasts - (Gr. trophe = nutrition) outer layer of cells on blastocyst that will generate the embryonic part of the placenta.
  • uterine wall - the site of normal blastocyst implantation.
  • zona pellucida - glycoprotein shell that surrounds the oocyte through to blastula stage of development.
  • zygote - The first (diploid) cell stage following fertilization of the (haploid) oocyte by the (haploid) spermatozoa. This is the first cell of the conceptus which will divide mitotically initially into two blastomeres.



Cite this page: Hill, M.A. 2017 Embryology Week 1 Movie. Retrieved September 22, 2017, from https://embryology.med.unsw.edu.au/embryology/index.php/Week_1_Movie

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© Dr Mark Hill 2017, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G