enow.com Web Search

Search results

  1. Results from the WOW.Com Content Network
  2. Comparative embryology - Wikipedia

    en.wikipedia.org/wiki/Comparative_embryology

    Observing embryos of different species, he described how animals born in eggs (oviparously) and by live birth (viviparously) developed differently. He discovered there were two main ways the egg cell divided: holoblastically , where the whole egg divided and became the creature; and meroblastically , where only part of the egg became the creature.

  3. Mammalian embryogenesis - Wikipedia

    en.wikipedia.org/wiki/Mammalian_embryogenesis

    The difference between a mammalian embryo and an embryo of a lower chordate animal is evident starting from blastula stage. Due to that fact, the developing mammalian embryo at this stage is called a blastocyst, not a blastula, which is more generic term. There are also several other differences from embryogenesis in lower chordates.

  4. Embryo drawing - Wikipedia

    en.wikipedia.org/wiki/Embryo_drawing

    Images of embryos provide a means of comparing embryos of different ages, and species. To this day, embryo drawings are made in undergraduate developmental biology lessons. Comparing different embryonic stages of different animals is a tool that can be used to infer relationships between species, and thus biological evolution. This has been a ...

  5. Evolutionary developmental biology - Wikipedia

    en.wikipedia.org/wiki/Evolutionary_developmental...

    They argued that the embryos of 'higher' animals went through or recapitulated a series of stages, each of which resembled an animal lower down the great chain of being. For example, the brain of a human embryo looked first like that of a fish , then in turn like that of a reptile , bird , and mammal before becoming clearly human .

  6. Israeli scientists create model of human embryo without eggs ...

    www.aol.com/news/israeli-scientists-create-model...

    Scientists in Israel have created a model of a human embryo from stem cells in the laboratory, without using sperm, eggs or a womb, offering a unique glimpse into the early stages of embryonic ...

  7. Animal embryonic development - Wikipedia

    en.wikipedia.org/wiki/Animal_embryonic_development

    In animals, the process involves a sperm fusing with an ovum, which eventually leads to the development of an embryo. Depending on the animal species, the process can occur within the body of the female in internal fertilization, or outside in the case of external fertilization. The fertilized egg cell is known as the zygote. [2] [5]

  8. von Baer's laws (embryology) - Wikipedia

    en.wikipedia.org/wiki/Von_Baer's_laws_(embryology)

    The embryos, also, of distinct animals within the same class are often strikingly similar: a better proof of this cannot be given, than a circumstance mentioned by Agassiz, namely, that having forgotten to ticket the embryo of some vertebrate animal, he cannot now tell whether it be that of a mammal, bird, or reptile.

  9. Human embryonic development - Wikipedia

    en.wikipedia.org/wiki/Human_embryonic_development

    Human embryonic development covers the first eight weeks of development, which have 23 stages, called Carnegie stages. At the beginning of the ninth week, the embryo is termed a fetus (spelled "foetus" in British English). In comparison to the embryo, the fetus has more recognizable external features and a more complete set of developing organs.