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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.
After internal fertilization and the habit of laying eggs in terrestrial environments became a reproduction strategy amongst the amniote ancestors, the next major breakthrough appears to have involved a gradual replacement of the gelatinous coating covering the amphibian egg with a fibrous shell membrane. This allowed the egg to increase both ...
The largest living amphibian is the 1.8 m (5 ft 11 in) South China giant salamander (Andrias sligoi), but this is dwarfed by prehistoric temnospondyls such as Mastodonsaurus which could reach up to 6 m (20 ft) in length. [7] The study of amphibians is called batrachology, while the study of both reptiles and amphibians is called herpetology.
Reptiliomorpha (meaning reptile-shaped; in PhyloCode known as Pan-Amniota [2] [3]) is a clade containing the amniotes and those tetrapods that share a more recent common ancestor with amniotes than with living amphibians (lissamphibians).
Temperature-dependent sex determination (TSD) is a type of environmental sex determination in which the temperatures experienced during embryonic/larval development determine the sex of the offspring. [1] It is observed in reptiles and teleost fish, with some reports of it occurring in species of shrimp.
This capsule also prevents the egg from drying out. The vitelline membrane is a membrane surrounding the egg. Upon fertilization, this membrane splits off from the surface of the egg and the space between the vitelline membrane and the embryo is filled with perivitelline fluid. This fluid surrounds the embryo and yolk plug.
The characteristic quivering abdomen caused by movement of tadpoles within a pregnant female Limnonectes larvaepartus.. Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a term used as a "bridging" form of reproduction between egg-laying oviparous and live-bearing viviparous reproduction.
If, in this transit, it meets with sperm, the egg selects sperm with which to merge; this is termed fertilization. The fertilization usually occurs in the oviducts, but can happen in the uterus itself. The zygote then implants itself in the wall of the uterus, where it begins the processes of embryogenesis and morphogenesis. When developed ...