Onthestate ofaggregation ofnewlysecreted procollagen (collagen/segment-long spacing/dilution-concentration effects/sedimentation analyses/electron microscopy)

ofwhole culture medium. Incontrast toresults from electron microscopy, analysis byvelocity density gradient sedimentation orsedimentation equilibrium indicated theexclusive presence ofprocollagen orpartially processed procollagen monomers insolution. These contradictory data can bereconciled ifprocollagen exists inmonomeric formwhen greatly diluted (as inculture medium), andinspecific aggregated form (SLS) athigh concentration. Webelieve that cells invivo secrete procollagen inhigh, local concentration packaged intheSLS form. Wepropose that such zero-D arrayed packages aretheprecursors ofnative collagen fibrils. Thepresence oflarge numbers ofprocollagen aggregates in zero-D array, analogous topacking ofadenosine triphosphoric acid (ATP)-produced segment-long-spacing crystallites (SLS)