BACKGROUND The aim of this study was to assess the expression and mechanisms of
fibroblast growth factor 4 in
polydactyly of the thumb induced by
cytarabine. MATERIAL AND METHODS Rats were intraperitoneally injected with
cytarabine at different gestation periods (12.5 days, 13.5 days, and 14.5 days) to establish a
polydactyly of the thumb model. Then, the expression of FGF4 in
polydactyly was studied by whole-mount in situ hybridization. We used
hematoxylin &
eosin stain and cartilage
stain to investigate the development of the skeleton and tissues in the embryo. Pictures were taken to determine the general shape of the
deformity, then X-rays were taken to detect bone distortion of the rats born with a congenital malformation. RESULTS In the experimental group (11.5 days, 12.5 days, 13.5 days, and 14.5 days), whole-mount in situ hybridization showed that the FGF4 expression at the tip of the embryonic limb bud was significantly increased compared with the control group and FGF4 was distributed in a wider range and lasted longer than in the control group (P<0.01). HE staining and cartilage staining showed that there was an extra metacarpal bone and a phalanx in the rats with
polydactyly of the thumb (P<0.01). Images of the deformed limbs showed
polydactyly and
syndactyly of the thumb in the rats. Further X-ray examination revealed 1 extra metacarpal bone and 1 extra phalanx. CONCLUSIONS
Cytarabine can induce
polydactyly and
syndactyly of the thumb in rats. In this process,
cytarabine can induce the expression of FGF4 on the tip of the embryonic limb bud, which further leads to abnormal development of the embryonic limb bud and eventually causes a congenital
deformity.