Forelimb bud appears on

(26 days) (135-IBS 7th) (125-1.B.Singh 8th)Timetable of some events* The forelimb bud appears about the 26th day (end of 4th week)* The hind limb bud appears about the 28th dayThe limbs become paddle shaped after about 4 days (5th week) and grooves between the future digits (digital rays) can be seen by the 36 the day (6th week). By the 50 th day or so (8th week) the elbows and knees are established and the fingers and toes are free. Rotation of limbs occurs during the 7th week. Cartilaginous models of bones start forming in the 6th week. And primary centres of ossification are seen in many bones in the 8th week. They are present in all long bones by the 12th week* The extremities are most susceptible to teratogens during the 4th to 7th week and slightly less susceptible in the 8th week