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Fertilization is the fusion of gametes to produce a new organism. 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.
English: Amphibian Egg: 1. Jelly Capsule 2. Vitelline Membrane 3. Perivitelline Fluid 4. Yolk Plug 5. Embryo The jelly capsule is designed to protect the embryo from the outside environment. This capsule also prevents the egg from drying out. The vitelline membrane is a membrane surrounding the egg.
A pair of clicking stream frogs (Strongylopus grayii) in amplexus Orange-thighed frogs (Litoria xanthomera) in amplexusAmplexus (Latin "embrace") is a type of mating behavior exhibited by some externally fertilizing species (chiefly amphibians and horseshoe crabs) in which a male grasps a female with his front legs as part of the mating process, and at the same time or with some time delay, he ...
In amphibians, the development of the animal-vegetal axis occurs prior to fertilization. [1] Sperm entry can occur anywhere in the animal hemisphere. [2] The point of sperm entry defines the dorso-ventral axis - cells opposite the region of sperm entry will eventually form the dorsal portion of the body. [1] [3]
A relatively short time after fertilization, the cortical cytoplasm, located just beneath the cell membrane, rotates by 30 degrees, which results in the creation of the gray crescent; its establishment determines the location of the dorsal and ventral (up-down) axis, as well as of the anterior and posterior (front-back) axis and the dextro ...
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A cross between a toad, Amietophrynus regularis, and a frog, Rana fusca, would not produce a viable embryo, but fertilization of a toad egg by an irradiated frog sperm would produce a haploid larva. [1] Parthenogenesis has also been induced in Pelophylax nigromaculatus by pricking an egg with a needle. [2]