Age- and region-dependent concanavalin A reactivity of chick wing-bud mesoderm cells

Abstract

MORPHOGENETIC potential of embryonic chick limb mesoderm cells declines with time beginning at approximately stage 24 of development¹. This decline occurs in a proximo-distal direction². Accompanying the loss of morphogenetic potential there is an age-dependent decline in the ability of limb and axial mesoderm to sort from one another in a randomised mixture of cells^1,3,4. Due to the age-dependent decline in both morphogenetic potential and the sorting ability of the limb mesoderm cells, it has been suggested that the decline in morphogenetic potential may be related to changes occurring at the cell surface⁵. Cell surface carbohydrate moieties have been postulated to play an integral part in cellular interactions⁶. Because of their high degree of carbohydrate-binding specificity⁷, plant lectins, such as concanavalin A (con A), Ricinus communis agglutinin (RCA), and wheat germ agglutinin (WGA), have been used to monitor cell surface changes which occur during development^7–13. These changes manifest themselves as differences in lectin-induced agglutinability of cells, and changes in number and distribution of lectin binding sites on the cell surface. This study was designed to determine if there were cell surface changes accompanying the decline in morphogenetic potential of the limb mesoderm cells, which could be detected by the use of plant lectin probes. We report here that there is a slight increase in RCA-induced agglutination of chick wing-bud mesoderm cells with increasing developmental age. There is also a significant age-dependent, proximo-distal decline in the susceptibility of chick wing-bud mesoderm cells to con A-induced agglutination between stages 19 and 26 of development. As such, there is a spatial as well as a temporal correlation between the decline of con A agglutinability and the decline of the morphogenetic potential of the chick limb-bud mesoderm cells.