noun (plural columellae /-ˈmelˌī/ /-ˈmelē/)
1 Zoology An ossicle of the middle ear of birds, reptiles, and amphibians.
- In amphibians, the columella shares the oval window with a second bone, the operculum, which communicates by way of an opercular muscle with the pectoral girdle.
- Sound is conducted through the middle ear via the stapes or columella (both are ear ossicles derived from the hyomandibular).
- A reduced hyomandibula associated with the quadrate in a fish's visceral skull evolved to form the ear ossicle called the stapes, or columella.
2 Zoology The axis of a spiral shell.
- The attachment site of the large Crepidula on the ventral side of the host shell and the presence of algal or sponge borings through the columella of the host indicate that the Oliva shell was possibly occupied by a hermit crab.
- On most specimens, the very thin columella in the median part of the shell is either broken or missing (probably resorbed).
- Higher values mean tube of the shell forms further from the coiling axis, resulting in a wider columella or hollow center
3 Botany The axis of the spore-producing body of some lower plants.
- The primary, stout capillitial branches arise from the upper part of the columella, dichotomously branching into flexuose threads.
- The stapes has neither a columella nor a stapedial foramen.
- In maize, endodermal cells are also involved in lateral root formation, giving rise to the newly formed epidermis and columella, while the remaining root-types are formed by the pericycle.
- Example sentences
- Three beautiful specimens are assigned to this new species, which is characterized by step-like whorls, coarse and prominent collabral costae and spiral caring on the ramp, and a columellar lip with two folds.
- It is characterized by strong, rounded, axial ribs, fine spinelets at the intersection of axial ribs and sharp spiral cords, subsutural cord, strong simple spiral cords, and an apparently smooth, glazed columellar lip.
- Most tip plasty and nasal width reduction surgery do not have external scars except for the columellar in an open rhinoplasty approach, and tiny skin puncture marks for external osteotomies (bone breaking to narrow nose).
Late 16th century: from Latin, 'small column'.
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