Animal morphogenesis can be summarized as a reconfiguration of a mass of cells. Although extracellular matrices that include rigid skeletal elements, such as cartilage/bones and exoskeletons, have important roles in morphogenesis, they are also secreted in situ by accumulated cells or epithelial cells. In contrast, recent studies of the skeleton construction of sponges (Porifera) illuminate a conceptually different mechanism of morphogenesis in which cells manipulate rather fine rigid materials (spicules) to form larger structures. Here, two different types of sponge skeleton formation using calcareous spicules or siliceous spicules are compared with regard to the concept of the production of rigid materials and their use in skeletons. The comparison highlights the advantages of their different strategies of forming sponge skeletons.

中文翻译：

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产生，携带/定位和连接：使用刚性材料的形态发生。

动物形态发生可以概括为大量细胞的重构。尽管包括刚性骨骼元素（例如软骨/骨骼和外骨骼）的细胞外基质在形态发生中具有重要作用，但它们也被积累的细胞或上皮细胞原位分泌。相反，最近对海绵（Porifera）骨架结构的研究揭示了一种概念上不同的形态发生机制，其中细胞操纵着相当精细的刚性材料（皮刺）以形成更大的结构。在此，就硬质材料的生产及其在骨架中的用途，比较了使用钙质针或硅质针的两种不同类型的海绵骨架的形成。比较突出了它们形成海绵骨架的不同策略的优势。