Portal de Periódicos da CAPES

Regeneration of lepidotrichia and actinotrichia in the tailfin of the teleostTilapia mossambica

1970; Elsevier BV; Volume: 22; Issue: 2 Linguagem: Inglês

10.1016/0012-1606(70)90157-0

1095-564X

Norman E. Kemp, Jae Ho Park,

Marine Biology and Environmental Chemistry

New fin rays developed at the tip of each old ray following excision of a wedge-shaped portion of the tailfin ofTilapia mossambica. Actinotrichia had begun to develop by 4 days after excision. Segmentation of lepidotrichia began at 5 days and branching at 7 days. The tailfin was completely restored in 3–4 weeks after excision. Regeneration of a rudimentary new tailfin had begun in some animals 4–6 weeks after excision of the tail through the muscular peduncle. Actinotrichia are formed by fusion of collagen fibrils of conventional diameter and inTilapia are cross-banded at a periodicity of about 490A˚. In addition to dark-staining major bands, corresponding to the a bands of conventional collagen fibrils, the actiontrichia have conspicuous intraperiod minor bands which correspond to the d bands of conventional fibrils. Ultrastructural and previously published chemical evidence supports the concept that the actinotrichia of teleosts and the ceratotrichia of elasmobranchs are homologous. The lepidotrichia consist of bilateral, segmented demirays of dermal bone, which is first deposited as an osteoid matrix between epidermis and a layer of osteoblasts. The interior of this matrix in regenerating rays had begun to calcify by 7 days and was heavily calcified by 13 days. A peripheral zone of matrix around each demiray, and thus adjacent to the bordering cells, remains uncalcified. Hydroxyapatite crystallites are deposited along and within collagen fibrils at separated mineralizing sites. These sites enlarge through fusion of individual mineralizing fibrils. It is suggested that actinotrichia after they are polymerized may be undergoing continual depolymerization proximally and that the collagen thus released may transfer to the growing tips of the lepidotrichia.