timeline of embryo

  • menstrual cycle changes

    menstrual cycle changes
    uterus endometrium (loss), ovary follicle development), ovulation release of egg
  • fertilization

    fertilization
    Fertilization is the fusion of haploid gametes (egg and sperm) to form the diploid zygote.
  • morula and blastocyst devlopment

    morula and blastocyst devlopment
    The inner cell mass (morula) will form the entire embryo. The blastocyst consists of cells forming an outer trophoblast layer. The blastocyst stage occurs the first and second week after fertilization.
  • implantation

    implantation
    Implantation occurs when the blastocyst attaches itself to the endometrium wall. For humans, this process begins at the end of week 1 with the most successful pregnancies implanting between 8-10 days post ovulation. Implantation continues through the second week of development.
  • gastrulation occurs

    gastrulation occurs
    The three germs layers develop known as the ectoderm, the mesoderm, and the endoderm.
  • heart begins to beat

    heart begins to beat
    By day 22 and 23, the human heart begins to beat which is the first functioning embryonic organ formed.
  • neural vascular development

    neural vascular development
    The hindbrain is supplied by two parallel neural arteries. The simple ectoderm epithelium over mesenchyme, smell crest comes from nasal plates, diaphragm, and more are starting to develop and appear.
  • hearing

    hearing
    The cochlear part of the otic vesicle elongates.
  • hearing- third trimester

    hearing- third trimester
    The vibration of the maternal abdominal wall induces a startled response of the fetus.
  • birth

    birth
    The thyroid TSH levels increase and the zona glomerulosa, zona fasiculata are present.