Glossary of plant morphology flowers, a tube or cup-like hypanthium (floral tube) is formed above or around the ovary and bears the sepals, petals, and stamens. There may also be a nectary producing nectar. Nectaries may develop on or in the perianth, receptacle, androecium (stamens), or gynoecium. In some flowers nectar may be produced on nectariferous disks. Disks may arise from the receptable and are doughnut- or disk-shaped. They may also surround the stamens (extrastaminal), be at the stamen bases (staminal), or be inside the stamina (intrastaminal). Finally, the actual reproductive parts form the innermost layers of the flower. These leaf primordia become specialised
Calyx of Held third postnatal weeks, around the time of hearing onset, the calyx of Held develops its characteristic, highly fenestrated (many openings) appearance. Fenestration results in the membrane being reduced to numerous small compartments, which increase surface area of the presynaptic cleft. As the membrane becomes increasingly pinched into these bulb-like structures, synaptic vesicles are further grouped into these spaces, resulting in an increased number of docked vesicles. To compensate for the available spaces in the calyx, glial cells with glutamate receptors and transports are used to fill open spaces, ensuring efficient uptake of glutamate in the synapse. This physical change in