Which process is unique to frog embryos compared to mammals?

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Frog embryos exhibit uneven holoblastic cleavage, which distinguishes their developmental process from that of mammals. In frogs, the cleavage pattern is influenced by the distribution of yolk within the egg. The uneven distribution leads to larger blastomeres at one pole and smaller ones at the other, creating a specific arrangement that is characteristic of amphibian development.

This type of cleavage is important because it reflects the energy reserves contained within the yolk; as the embryo develops, the larger cells divide more slowly than the smaller ones. This uneven division plays a critical role in the subsequent stages of development, including gastrulation and organ formation.

In contrast, mammals typically go through a more regulated cleavage pattern that can be either holoblastic or meroblastic depending on the amount of yolk present. However, many mammals, especially those with a significant amount of yolk, exhibit complete holoblastic cleavage, which is different from the uneven holoblastic cleavage seen in frogs.

Furthermore, the presence of an amniotic sac is specific to amniotes and does not apply to frogs, while the formation of a primitive streak is a characteristic feature of many vertebrates, including both frogs and mammals, but in different contexts and stages of development. Thus, uneven hol

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