This drawing shows the actual size of the embryo at 6 weeks. The embryo is about 1/4 of an inch long.

At 18 days after conception the embryo consists of 3 layers of cells: endoderm, mesoderm, and ectoderm. Thickening of the ectoderm leads to the development of the neural plate.

Shigehito Yamada, and Tetsuya Takakuwa (2012). Introduction – Developmental Overview of the Human Embryo, The Human Embryo, Dr. Shigehito Yamada (Ed.), ISBN: 978-953-51-0124-6, …

Below is a table of the 23 Carnegie stages of development and their descriptive features.

Once one of the sperm is successful, development begins. The fertilized egg divides into multiple cells on its way to the uterus. After about five days, it forms a structure called a blastocyst. The …

Once the embryo is implanted in the uterus, the pregnancy can be detected and is considered clinical. The embryo develops a primitive streak, which is the precursor of the spinal cord and …

Students will research the different stages of human embryo development. Next, the teacher will give a PowerPoint presentation about a category of birth defects known as neural tube defects …