This is an embryo at the 16-cell stage, when it has changed from a zygote into a morula. It is in the process of dividing into a hollow ball of cells-the blastocyst-which will eventually implant in the lining of the uterus.
Around four days following fertilization, fluid begins to collect within the morula (see You are 2 Weeks and 3 Days). This creates a separate outer cell layer, one cell thick that encapsulates an inner mass of cells. The inner layer will become the embryo, and the outer layer the placenta (see You are 4 Weeks and 6 Days). The whole structure now consists of approximately 58 cells and is termed the "blastocyst."
The blastocyst spends several days within the cavity of the uterus before implanting. The morula had an impenetrable outer surface as it traveled, but this disappears as the blastocyst prepares for implantation.
It's not as clear whether acupuncture can improve fertility in couples not undergoing treatment, but it is thought to improve male fertility by improving sperm health and reducing stress, a factor that can impede the chances of conception.
I certainly found that once I'd told people I was trying to have a baby, they were inordinately interested in the process. It was difficult, especially in the week when I was waiting to find out if I'd conceived. The best way to deal with it is to respond by saying that you'll let people know if there's news. If you're struggling to conceive, telling people you're having difficulties should help stop them from asking.
Excerpted from Pregnancy Day by Day.
Copyright Â© 2009 Dorling Kindersley Limited.
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