From fertilization to the completion of the embryo, the development of offspring can be broken down into a few distinct stages. The following sequence accurately depicts the stages of early embryonic development: Fertilization, Cleavage, Blastula Formation, Gastrulation, and Neurulation.
Fertilization is the process by which a male gamete (sperm) fuses with a female gamete (egg) to form a zygote. The zygote then divides in a process known as cleavage, which ultimately results in the formation of a blastula. During the process of gastrulation, the blastula is transformed into an embryo with distinct internal and external structures by the process of cell movements and reorganization. Finally, during the neurulation stage, the embryo begins to form its nervous system.
In addition to these main stages, the timing of offspring development can also be affected by a variety of environmental and genetic factors. For instance, temperature, presence of toxins, and the size of the embryo can all affect the timing of offspring development, as can intraspecific variation in developmental event timing. Furthermore, the growth rate of offspring is determined by both temperature and allometric constraints.
In conclusion, the development of offspring can be broken down into distinct stages, with Fertilization, Cleavage, Blastula Formation, Gastrulation, and Neurulation being the most commonly accepted stages. Additionally, the timing of offspring development can be affected by both environmental and genetic factors, making the precise timing of each stage unpredictable.