Sea Urchin Hyalin

Résumé du livre

Hyalin, the extracellular matrix protein of sea urchin embryos, was examined by immunofluorescence. Prior to fertilization hyalin was confined to cortical granules. At fertilization hyalin was released from some of the cortical granules as part of the visible fertilization wave. Further hyalin accumulation on the cell surface occurred in the succeeding 2-3 min as additional cortical granules were released. The hyalin fused to form a continuous extraembryonic layer. Regeneration studies showed that new accumulations of hyalin were initiated by ectoderm cells at early gastrulation. Regeneration did not occur prior to this developmental time, nor was there new hyalin accumulation on mesoderm or endoderm cells. Hyalin accumulated only on the apical surface of ectoderm cells. In binding studies, cells of all three germ layers had an affinity for hyalin prior to gastrulation. The affinity was retained by ectoderm and endoderm but was lost by primary mesenchyme cells at the beginning of gastrulation. The loss in affinity was specific for hyalin and occurred at the time when primary mesenchyme cells normally leave the blastoderm to invade the blastocoel.