Final answer:
The embryonic period is a stage of prenatal development characterized by major developments in the embryo, including the formation of organs and the neural tube. Genetic defects or harmful environmental exposures during this period can have serious effects on the embryo.
Step-by-step explanation:
The embryonic period is a stage of prenatal development that occurs from the third week to the eighth week after fertilization. During this period, the developing human is referred to as an embryo. It is characterized by cell division, migration, and differentiation, and by the end of this period, the organ systems are structured in rudimentary form.
During the embryonic stage, the embryo undergoes major developments, including the formation of basic structures like the head, chest, and abdomen. The heart starts to beat, and organs begin to form and function. The neural tube, which develops into the spinal cord and brain, also forms during this stage.
Genetic defects or harmful environmental exposures during the embryonic period can have serious effects on the developing embryo. It is a critical period of development, and factors that can impact it should be carefully considered.