-
Day 1
Fertilization, zygote, Secretory Phase -
Day 4
Blastocyst hatches -
Day 8
Implantation -
Day 13
Chorionic Cavity -
Day 18
Neural neurogenesis, neural glove and folds are first seen -
Day 23
The Heart begins to beat and the first functioning embryonic organ formed. -
Day 27
The neural tube is normally completely closed, ventricular system now separated from amniotic fluid. -
Day 31
Head- 1st, 2nd and 3rd pharyngeal arch, forebrain, site of lens placode, site of otic placode, stomodeum
Body- heart, liver, umbilical cord, mesonephric ridge visible externally as bulges. -
Day 36
The spine is starting to form, with the very beginnings of the central nervous system. Blood vessels are also forming into what will become the umbilical cord -
Day 41
Telencephalon areas of the future archicortex, paleocortex, and neocortex, become visible. smell olfactory nerve fibres enter the brain. Eyelid folds develop. -
Day 48
Skeletal muscle forms by fusion of mononucleated myoblasts to form multinucleated myotubes. Bone is formed through a lengthy process involving ossification of a cartilage formed from mesenchyme. -
Day 50
Scalp vascular plexus visible. Upper limbs begin to rotate ventrally -
Day 53
Fingers and Toes start to lengthen. Upper and lower limbs rotate. -
Day 56
The upper limbs longer and bent at elbow, hands and feet turned inward, foot with separated digits, wrist, hand with separated digits. Chorionic cavity is now lost by fusion with the expanding amniotic cavity
