In the first two months, the embryo continued to divide and differentiate, producing various cells and forming various tissues and organs. This is a tender and sensitive period of development, and its resistance and adaptability to various external stimuli are very poor, so we should pay great attention to safety.

Embryo development is the process from fertilized egg to embryo leaving the egg membrane. Invertebrate embryologists often extend their concept to postnatal development, until sexual maturity, and even the whole life history.

Extended data:

Although there are many kinds of animals, embryo development still has a similar process, which can be divided into fertilization, cleavage, morula, blastocyst, gastrula and organ formation.

In addition, during the embryonic development of vertebrates, the common features of various animals (such as skin) will first appear, and then specialized structures (such as fish scales) will gradually develop. The more complex species are quite similar to the more primitive species at first, and then the variation will gradually increase with the development time.

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