Fact Sheet - Prenatal Development

• The dorsal and ventral surfaces are distinguishable within the blastocyst by 4 to 5 days postfertilization.

• The neural tube is initially open at each end. The end of the neural tube near the brain normally closes approximately 24 days after fertilization.

• The opening at each end of the neural tube is called a neuropore. The end of the neural tube near the brain is called the rostral neuropore and normally closes approximately 24 days after fertilization.

• The rostral neuropore closes approximately 24 days after fertilization.

• By approximately 15 days after fertilization, the plane of bilateral symmetry is evident as the embryo's right and left sides are identifiable as is the location of the developing head.

 

• In response to implantation of the blastocyst, the cells of the endometrium enlarge and accumulate nutrients such as glycogen, lipids, and minerals. This process is sometimes called the "decidual reaction."

 

• Following implantation, the cells of the endometrium become engorged with nutrients in order to sustain the rapidly developing blastocyst.

 

• Following implantation, the cells of the uterus surrounding the blastocyst become engorged with nutrients in order to sustain the rapidly developing blastocyst.

  

• The trophoblast cells of the blastocyst give rise to the synctiotrophoblast & cytotrophoblast.

• Ossification is underway in most bones by 10 weeks after fertilization.

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