Silene invisa cyme of up to three flowers at the top of the stem. Each flower has a bell-shaped calyx of fused sepals lined with ten green veins and covered in short, glandular hairs. The strap-shaped or rectangular petals have blunt tips or may be notched. They are whitish to pinkish or lavender and sometimes barely protrude from the calyx. Silene invisa Silene invisa is a species of flowering plant in the pink family known by the common names red fir catchfly and short-petaled campion. It is endemic to California, where it is known only from the southernmost Cascade Range and northernmost
Calyx of Held embryonic calyx formation. One characteristic that distinguishes Eph proteins and their receptors from other signaling systems is their ability to transmit information bidirectionally. Forward and reverse signaling in VCN and MNTB cells is essential for the proper number and formation of VCN and ipsilateral MNTB projections in the calyx. Eph proteins also ensure that while axons pass through the ipsilateral MNTB, branching and final termination of these projections only occur in the contralateral MNTB, possibly because the proteins are only targeted towards specific regions on the axons. Overall, there are two ultrastructural changes that occur in the calyx of Held.