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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]
The main processes involved in the embryonic development of animals are: tissue patterning (via regional specification and patterned cell differentiation); tissue growth; and tissue morphogenesis. Regional specification refers to the processes that create the spatial patterns in a ball or sheet of initially similar cells.
1 - morula, 2 - blastula 1 - blastula, 2 - gastrula with blastopore; orange - ectoderm, red - endoderm. Embryology (from Greek ἔμβρυον, embryon, "the unborn, embryo"; and -λογία, -logia) is the branch of animal biology that studies the prenatal development of gametes (sex cells), fertilization, and development of embryos and fetuses.
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.
Embryonic development of salamander, circa the 1920s Embryos (and one tadpole) of the wrinkled frog (Rana rugosa) Mouse and snake embryos. In animals, fertilization begins the process of embryonic development with the creation of a zygote, a single cell resulting from the fusion of gametes (e.g. egg and sperm). [5]
Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia (/ ˌ æ n ɪ ˈ m eɪ l i ə / [4]).With few exceptions, animals consume organic material, breathe oxygen, have myocytes and are able to move, can reproduce sexually, and grow from a hollow sphere of cells, the blastula, during embryonic development.
In humans, the embryonic period ends nine weeks after conception, after which time the term fetus is used instead of embryo. In many other animals, embryogenesis is considered complete only after hatching or birth. embryology embryonate Containing a developing embryo; e.g. an embryonated hen's egg, as opposed to an unfertilized egg. [2] endoderm
In embryology, Carnegie stages are a standardized system of 23 stages used to provide a unified developmental chronology of the vertebrate embryo.. The stages are delineated through the development of structures, not by size or the number of days of development, and so the chronology can vary between species, and to a certain extent between embryos.