Final answer:
The term referring to the developing embryo along with all associated structures is 'conceptus.' Initially a zygote, after fertilization it undergoes development to form the blastocyst, which then implants and is supported by extraembryonic structures.
Step-by-step explanation:
The term that refers to the developing embryo along with all its associated structures is conceptus. Following fertilization, a zygote is the initial stage when the sperm and egg combine, producing a diploid zygote. This zygote travels toward the uterus, undergoing several cleavage stages to increase the number of cells, forming structures such as the morula and eventually becoming the blastocyst. The blastocyst contains an inner cell mass that will develop into the embryo and trophoblasts that will develop into extraembryonic structures like the placenta. The formation of the amnion, yolk sac, allantois, and chorion supports the growing embryo, which implants in the uterine wall. Eventually, the developing human is called an embryo from weeks 3-8 and a fetus from the ninth week until birth.