Regeneration

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Fig. 1. Regeneration in fusiform-elongate shells: A-D: Alveolina gigantea Checchia-Rispoli. Microspheric generation. Palermo, Sicily, Middle Eocene. E: Pseudoschwagerina sp., megalospheric specimen, from Palazzo Adriano, Sicily, Permian. A: a fragment of the polar realm of the shell cut in the axial direction shows two periods of regeneration (red lines designated by arrows) during late ontogeny. B: a similar fragment cut in a direction perpendicular to the shell axis, with one broken surface, that has been regenerated in an attempt to restore the cylindrical shape of the shell. At such a late ontogenetic stage the original shape of the shell can not be regained through regenerative growth. Incident light micrographs. C-D: regeneration at an early stage of ontogeny: C. the rate of elongation was higher in the regenerated half of the shell (red curve) than in the undisturbed half, until the range of elongation that is characteristic for the species was attained again. Note the absence of elongation index increase in the early whorls broken away (arrow). Data from Hottinger, 1962. D. Compare the camera lucida drawing of an axial section: broken early shell in gray, regenerated shell in black. E: in a fusulinid the regeneration of the broken whorls 3-6 produces an almost perfect equatorial spiral after only two more whorls of growth; (Hottinger, 2006; fig. 78 [1] CC/BY-NC-SA)

Definition

  • according to Hottinger (2006):

REGENERATION – repair of the shell after injury, first by closing chamber cavities and subsequently by locally accelerated growth, until a specific outer shape of the shell is more or less perfectly restored. Shell fragments without an embryo may regenerate. This fact confirms that the nucleus of the cell moves away from the center of the shell during ontogeny.


See also


References

Hottinger (2006), Illustrated glossary of terms used in foraminiferal research. Carnets de Géologie, Memoir 2, ISSN 1634-0744.

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