A Zygote.
Once the zygote becomes an embryo it starts developing all of its organs, nervous system etc. then after 8 weeks of development everything is there so it becomes a fetus, and the fetus just grows bigger.
The form from the embryo.
If it's a human embryo, about nine months. If you're a mouse embryo, about twenty days. Gestation time in mammals varies species to species, but it's generally safe to say the bigger the animal, the longer the gestation.
Frog
Your body is the sum of all its systems. There are no "other systems". All the body's systems have to be working together or the body will not be able to stay alive.
All body systems are controlled by the brain.
The link between all body systems is the brain. The brain regulates all of the body systems using a variety of hormones and signals.
all systems
Yes, aging affects the function of all body systems.
All the systems of the body work together; there are no isolated systems.
The formation of a human embryo is complete by the end of the eighth week of pregnancy. At this stage, all major organs and systems have formed, and the embryo is then referred to as a fetus.
It has got a dependent gametophyte on main sporophytic plant body and embryo develops inside the embryo sac in all flowering angiospermic plants.