Here is my weekly photo!
What happened this week:
‘Primitive streak’ (the forerunner of the brain and spinal cord) is evident. Baby’s head is now detectable. A groove forms in the primitive streak, setting stage for three layers of tissue: ectoderm, mesoderm and endoderm. The ectoderm will form skin, hair, linings of ear, nose, mouth, glands and the nervous system. From the endoderm, baby will develop lungs, tongue, glands, bladder and digestive tract. From the mesoderm, baby will develop muscles, bones, blood cells, heart, excretory and reproductive systems. The next 10-30 days are crucial for development of the nervous system and heart. Early heartbeats, facial features and lung buds begin to form.