Abnormal patterns of ossification in the hands of foetuses produced by cyclophosphamide administration to pregnant rats

Skeletal Malformations Induced by Mitomycin C in Chick Embryos

“…Its antimitotic activity has been observed to suppress cell growth in vitro (Singh et al 1974) and cartilage cells in particular are suppressed, as seen by their uptake of S35 , and the marked shortening of treated bones ( P < 0.001) may be explained on the basis of this suppression of growth.…”

“…Hindlimb bones were more frequently involved and the most affected part was the distal end of the extremities, i.e., the phalanges. Since the skeletal differentiation in the limbs, i.e., mesodermal condensation, chondrification and ossification, proceeds in a proximodistal sequence in general (Zwilling & Hansborough 1956, Amprino 1965, Milaire 1965, the suppressive effect of mitomycin on the proliferating and differentiating mesenchyme (Singh et al 1974) is likely to depend on the stage of differentiation of the limb buds at the time of the administration of the drug. The skeletal elements which differentiate at an early stage will be more resistant than those which differentiate later.…”

“…The hindlimb bones were more involved than the forelimb bones this being related to the difference in time of initial development and rate of growth of the limbs. Such a stage dependent sequence of bone involvement is known to occur (Singh & Sanyal 1974).…”

“…However, dead cells may be removed and replaced by mitotically active cells which subsequently attempt to reconstitute the tissue or organ. Such repair and regeneration is known to 'occur in fetuses after radiation damage (Hicks et al 1957, Sakurai 1968 and after radiomimetic drugs (Kreybig & Schmidt 1967, Chaube et al 1967, Singh & Sanyal 1974. The capacity for such regeneration and the ultimate outcome is dependent on the number of mitotically active cells that survive and the tissue remaining for such organogenesis.…”