![seashell zigzag plant seashell zigzag plant](https://i.etsystatic.com/10984992/r/il/d5aff0/1985586519/il_794xN.1985586519_6h2w.jpg)
The existing edge pattern induces excitatory firing (red) the older, previous pattern is inhibitory (blue), indicated in the upper trace. ( C) Schematic illustration of the model. ( B) Schematic representation of the mantle, showing the neurosensory cells, the circumpallial axons connecting these cells, and the neurons that control shell and pigment secretion. The EM of a nautilus mantle is shown, with secretory epithelial cells stained green and nerve axons stained red.
![seashell zigzag plant seashell zigzag plant](https://i.pinimg.com/736x/40/96/af/4096af2de7d4c94a2cb7cf359f2449cc.jpg)
Neural recordings and neural cell ablation experiments have further verified the role of neural control in shell growth and repair ( 6, 11, 12).įig. The original evidence from gastropods has been extended to other mollusk taxa, including bivalves ( 8) and cephalopods, where improved experimental methods confirm clearly the role of neural control ( 9, 10). From this evidence, it was proposed that neural-stimulated secretion controls shell growth ( 4, 7). These fibers were later shown to have active synapses with secretory gland cells and synaptic inputs from other sensory organs in the mantle. Early EM studies of the mantle recorded an extensive distribution of nerve fibers among the secretory cells ( 1, 6, 7). This hard shell is covered by a thin organic layer of proteinaceous secretions, believed to function in regulating calcium crystallization ( 5). The shell itself is composed of crystal structures of calcium carbonate interspersed with associated proteins and other organic compounds, some of which are pigmented and arrayed in intricate patterns ( 3, 4).
![seashell zigzag plant seashell zigzag plant](https://i.pinimg.com/originals/08/a3/0c/08a30c0f138751cb54c2f0d0e55c142c.jpg)
Most of this evidence has been gained by detailed studies of the mantle, a tongue-like protrusion of the mollusk that wraps around the edge of the shell and deposits new shell material and pigment at the shell's growing edge (see Fig. Accumulating evidence now indicates clearly that shell growth and patterning are under neural control and that shell growth and pigmentation is a neurosecretory phenomenon. Seashells display a remarkable variety of ornate pigmentation patterns.