Question on the reproductive process in humans

[Dovi]

In my Life Sciences (Biology) preliminary examination on Thursday, there was a question where you were required to fill in the steps of the human reproductive process. It had a diagram indicating the steps in chronological order, and provided a list of terms to use to fill in the missing steps.

Now, in between 'Zygote' and 'Embryo', it seems they wanted us to fill in 'Implantation', and that's what most people have done. But according to my textbook, it says "As the zygote moves along [the fallopian tubes], it divides by mitosis to form two cells and then four cells and so on, until it forms a ball of cells. This ball of cells is called an embryo. .... The embryo settles on the uterus wall and sinks into it, embedding itself completely in the lining of the uterus. This process is called implantation." So based on what I studied, I said implantation was the step after the zygote became an embryo, but there wasn't any viable option out of the list to substitute between zygote and embryo, so now I need to know whether the textbook was wrong, or whether the question paper was wrong, 'cause if it's the former I'll have to lodge a complaint with the Department of Education as the paper was set by them.

So, basically my question is: Does the zygote become an embryo before or after implantation?

 

[HapticSimian]

Having a quick browse around several wiki pages, the structure that undergoes implantation is referred to, seemingly almost synonymously, as 'zygote', 'blastocyst' and 'embryo'. I think you're dealing with ambiguous usage of scientific terms - one of my biggest pet hates in examinations when the bloody examiners don't know what they want to ask.

The most complete but worst referenced article seems to be this one, on Human Embryogenesis. Have a read through - maybe it helps a bit.