ISSN:
0003-276X
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Medicine
Notes:
Embryonic chicks were treated with exogenous L-thyroxine or with thiourea at eight days of incubation and the subsequent development of the tibia studied.The weight of the tibia was 62% lower than that from normal embryos, and the length of the tibia 24% below normal in the embryos treated with thiourea. This reduced rate of growth was shown to be due to a reduction in the rate of maturation of chondroblasts into chondrocytes, reduced chondrocyte hypertrophy and defective deposition of acid mucopolysaccharide into the cartilage matrix. Osteogenesis per se was unaffected. It was concluded that thyroxine plays a role in the control of chondrocyte maturation and in cartilage matrix production during normal development.The epiphyses of the tibiae from the embryos treated with thiourea were extensively eroded, invaded by marrow and more fragile than those from untreated embryos, indicating that thyroxine is essential for the maintenance of the integrity of the articular cartilage. An abnormal core of bone developed within the proximal epiphysis of these embryos.Exogenous thyroxine at concentrations as low as 100 pg/embryo also reduced the growth of the tibia below that seen in untreated embryos. Evidently the cells of the skeleton are sensitive to both lowered and increased levels of circulating thyroxine.
Additional Material:
3 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/ar.1091760104
