What term refers to the length of time an embryo takes to develop?

The term "gestation" specifically refers to the length of time an embryo or fetus develops within the womb of a parent organism, spanning from conception to birth. In mammals, gestation duration can vary significantly between species and is a critical factor in the reproductive biology of those species.

During gestation, the developing embryo undergoes a series of maturation processes where various systems and organs form, preparing it for life outside the womb. This period is essential for the proper development of the fetus, allowing for growth, differentiation, and the establishment of physiological systems necessary for survival.

The other terms mentioned relate to different aspects of development. The fetal period, for instance, is a specific phase within gestation that refers to the later stage of development, primarily when the major structures have formed. Incubation typically refers to the period that eggs spend under specific environmental conditions until they hatch, relevant to species that reproduce through laying eggs rather than live birth. Embryogenesis, on the other hand, describes the early stages of development immediately following fertilization up until the end of the embryonic stage, but does not encompass the entirety of gestation leading up to birth.