The Timing of Appearance of Ossification Centers of Carpal and Tarsal Bones in Mouse Newborns

Abstract

Abstract We examined the time and order of appearance of ossification centers of various bones in hand and foot in newborn Jcl:ICR mice by staining on days 22, 24, 26 and 28 post coitum (pc) by the alcian blue and alizarin red S staining procedure. The time of appearance of ossification centers of the carpal bones was from about day 22 pc to about day 26 pc, while the ossification centers of the tarsal bones appeared from preterm to about day 28 pc. The order of appearance of ossification centers of respective bones in mice was roughly similar to humans and rats. In carpal bones, ulnar sesamoid, centrale, fused 4th and 5th distal carpal and ulnare appeared first. Then, fused radiale and intermedium and 3rd distal carpal appeared. Finally, 1st distal carpal, 2nd distal carpal, and the last pisiform appeared. In the tarsal bones, fibulare and intermedium appeared first. Then, 1st distal tarsal, fused 4th and 5th distal tarsal and 3rd distal tarsal appeared. Finally, 2nd distal tarsal, centrale and tibiale appeared. In other mammals (humans, chimpanzees, rhesus monkeys and rats), it has been shown that the carpal and tarsal bone ossification of females starts earlier than that of males. However, in this study in mice, there was no such sex difference. The timing of ossification of carpal and tarsal bones in mice is of practical importance in determining the developmental status of hand and foot of mice in the field of neonatal teratology.