Study of the formation of prechondral blastemas in the autopodium of normal and polydactyl rats.
The nuclear volume fractions in chosen mesenchymal and prechondral zones were examined during formation of the prechondral rays in the autopodium of 14- and 15-day rat embryos. A morphometric analysis showed that formation of the prechondral blastemas was accompanied by a significant increase in the nuclear volume fraction in relation to the adjacent distal mesenchyme in both normodactyl and polydactyl embryos. The mean nuclear volume fraction in the prechondral blastema (the third metatarsal ray) is somewhat larger in normodactyl embryos, but the differences (in progressive means) are not statistically significant. The nuclear volume fractions at chosen sites in the mesenchymal zones at 14 and 15 days do not differ significantly in either normodactyl or polydactyl embryos. There are, however, significant differences between the nuclear volume fractions of the mesenchymal cells at the chosen sites in normodactyl and polydactyl embryos at both 14 and 15 days. The degree of enlargement of the nuclear volume fraction in the prechondral (chondrogenic) ray in relation to the mesenchyme is relatively greater in polydactyl embryos than in normodactyl embryos.
Gaspar
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D000818:Animals; D005121:Extremities / Q000196:embryology*; D010009:Osteochondrodysplasias / Q000473:pathology*; D051381:Rats; D011917:Rats, Inbred Lew