In Vitro Aggregation of Mixed Embryonic Kidney and Nerve Cells

Abstract

The possible role of nerve on growth of embryonic parenchymal organs such as kidney was explored by measuring macromolecular synthesis (DNA, RNA, and protein and three enzymes) in aggregates of mixed suspensions of cells from dissociated chick embryo kidney and nerve tissue . One and one-half to threefold increments in net synthesis of the three different types of macromolecules were observed in the mixed aggregates of kidney and nerve cells as compared with those of single organs or mixtures of kidney with nonneural cells . The addition of nerve-growth factor (NGF) did not significantly affect the results . Increased incorporation of label was paralleled by increases in chemically measured DNA and protein, suggesting an increase in growth in the mixed kidney-nerve aggregates compared with those of single tissues. Measurements of survival rate did not indicate increased cell stability in the mixed aggregates . The activities of three enzymes, acid phosphatase, alkaline phosphatase, and lactic dehydrogenase, were also enhanced two to four times in cultures of kidney plus nerve cells . Morphologic studies indicated a high degree of reorganization of tubular structures within the reaggregates of kidney cells alone or in those mixed with nerve . In addition, radioautographs of thymidine-3 H-labeled cells in the aggregates showed a high level of DNA synthesis in the reformed tubular cells . Electron micrographs revealed the presence of large numbers of nerve fibers containing microtubules in the mixed cell aggregates . The data suggest a significant role for nerve in the growth processes of embryonic parenchymal organs.

Self-assembly, self-organization and division of labour

“…Since Wilson's (1907) and Huxley's (1911Huxley's ( , 1912 experiments on sponges, it has been established that hydra and the early sea-urchin embryo can also reassemble, but the higher animals do not have this capability (Wolpert 1993, p. 25). Dissociated cells from the embryonic organs of vertebrates, however, can sort themselves into their original tissue organization (Townes & Holtfreter 1955;Medo¡ & Gross 1971). It is widely accepted that a process similar to self-assembly, could be responsible for the sorting of cells of di¡erent types in culture and could play an important role in cell re-arrangements during morphogenesis (Bard 1992, pp.…”

Getting to mammalian wound repair and amphibian limb regeneration: a mechanistic link in the early events

“…Subsequently, many others have extended these important studies . [15][16][17][18][19] Several years later, after establishing the Developmental Biology Laboratory in the Medical Services of the MGH, I spent several summers taking courses and working at the Marine Biological Laboratories at Woods Hole, Massachusetts . It was here, about 1958, that another distinguished lecturer, Marcus Singer from Western Reserve University, set the bells ringing again for me with an intriguing story of in situ organ self-assembly-namely, amphibian limb regeneration .21 Among other things, I took away the idea that programmed connective tissue matrix dismantling was a critical initial step for dedifferentiation.…”

Expression of Calbindin Immunoreactivity by Subpopulations of Primary Sensory Neurons in Chick Embryo Dorsal Root Ganglion Cells Grown in Coculture or Conditioned Medium

“…In cocultures, the fact that the appearance of calbindin-immunoreactive neurons coincides with an increase in the number of surviving DRG cells could be consistent with a trophic effect exerted by a skeletal muscle factor on proprioceptive neurons [Davies, 1986]. However, the increased number of growing DRG cells is more probably due to an im proved adhesion of the seeded ganglion cells onto extracellular matrix components sec reted by the subjacent layer of myoblasts, skin or kidney cells [Medoff and Gross, 1971;Schubert et al, 1983]. Indeed, under our cul ture conditions, CM produced by these cells did not affect the survival of DRG cells (table I) while these CM promote the presence of calbindin-immunoreactive sensory neurons.…”