Plant reproductive morphology is asexual, producing only spores. Similarly, flowers produced by the sporophyte may be described as "unisexual" or "bisexual", meaning that they give rise to either one sex of gametophyte or both sexes of gametophyte. The flower is the characteristic structure concerned with sexual reproduction in flowering plants (angiosperms). Flowers vary enormously in their construction (morphology). A "complete" flower, like that of "Ranunculus glaberrimus" shown in the figure, has a calyx of outer sepals and a corolla of inner petals. The sepals and petals together form the perianth. Next inwards there are numerous stamens, which produce pollen grains, each containing a
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