cardiac contractions begin aroud the 5th week of pregnancy. A few days after that their limb buds begin to form.
there are three stages. the first stage, the latent phase, is when you start notice contractions. your cervix will start to dilate. second stage, contractions start to feel different, your cervix is fully dilated and your body starts to push the baby out. third stage, the delivery of the placenta, about 5 to 30 minutes after the baby comes out. it is very important to remember the 4th and important stage: recovery. recommended reading: See related links
apex
Lower animals including Protozoa don't start life as embryo.
With a "c", then an "a"...
Implantation can start to occur as soon as 6-10 days after retrieval (I use "after retrieval" because embryos can be transferred on different days of development. Count the retrieval day as day 0). Five days after the retrieval a healthy embryo will have reached the blastocyst stage. Six-seven days after the retrieval, a healthy embryo will start breaking out of its hard outer shell and begin the implantation process. After the healthy embryo has implanted in the uterus it will not start secreting hCG for several more days. You will probably not be able to feel the implantation process.
contractions, start, stop (length)
When a hen lays a fertilized egg, there is no embryo inside. Embryo's only start to form once they are incubated.
No
The embryo is the baby plant. It has an embryo root to push its way eventually out of the seed coat, and embryo stem, and embryo leaves which will later start food production.
5 minutes
Cardiac cycle
When the baby is ready and sends out hormones that make contractions start