Difference between revisions of "Pore"

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(Created page with "__FORCETOC__ ==Definition== *''according to Hottinger (2006):'' '''PORE''' is a minute tubular perforation traversing a lamellar chamber wall, coated internally by an organi...")
 
 
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[[File:Fig 75.jpg|thumb|<font size="2">'''Fig. 1.''' The pore and its organic constituents; '''A:''' a pore in an inner chamber covered by an outer whorl, according to Leutenegger (1977), schematic, not to scale. '''B:''' Accumulation of mitochondria below a pore mouth in ''Bolivina'' sp., thus indicating the pores' main function: gas exchange. TEM micrograph of a section oblique to the surface ot the wall that exaggerates the thickness of the pore discs. The detachment of the outer lamella 2 ('''ouL 2''') is an artifact of preparation. x 24,000. Courtesy S. Reber-Leutenegger. '''C:''' Resin cast of pores in the lateral chamber wall of ''Nummulites partschi'' De La Harpe with trabeculae. The carbonates of the shell are dissolved with HCl. SEM graph x 1,000. '''D:''' Outer pore mouths in the lateral suface of chamber wall of ''Assilina''. Note the annular attachment of the interlamellar discs. SEM graph x 5,000. ''E:'' Inner pore mouths in the lateral chamber wall of ''Assilina'' shaped as eggholders (in order to keep the symbionts below their breathing chimneys). Note the annular suture of the pore plug. SEM graph x 5,000. '''C-E:''' from Hottinger, 1977. '''F:''' Perforation pattern on the dorsal surface of ''Challengerella persica'' (Recent, Persian Gulf): densely perforated porefields between imperforate ornamentation. SEM: oblique dorsal view of shell, x 30, and detail of porefield, x 500. '''G:''' Perforation pattern in ''Ammonia reyi'' Marie (Pliocene, Dar bel Hamri, Northern Morocco): densely perforated porefields between loosely perforated ornaments. SEM graphs of dorsal shell view (x 30) with detail (x 500). '''F-G:''' from Billman et alii, 1980; Abbreviations: '''bD:''' basal (pore) disc; '''Cy:''' [[cytoplasm]]; '''iL:''' [[inner lamella]]; '''ilD:''' interlamellar disc; '''iol:''' interlamellar organic lining; '''ls:''' lacunar system (in the cytoplasm); '''M:''' mitochondria; '''ML:''' median layer separating inner from outer lamellas; '''OL:''' Organic lining (here difficult to separate from plasmalemma of host); '''ouL 1:''' primary outer lamella; '''ouL 2''', '''ouL3:''' subsequent outer lamellas; '''P:''' [[pore]]; '''Pc:''' organic pore coat; '''Pl:''' plasmalemma; '''ppl:''' pore plug (note its porosity); '''Spl:''' (biomineralized) sieveplate; '''V:''' vacuole; (Hottinger, 2006; fig. 75)[http://paleopolis.rediris.es/cg/CG2006_M02/index.html] '''CC'''/BY-NC-SA)]]
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__FORCETOC__
 
__FORCETOC__
 
==Definition==
 
==Definition==
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*''according to Hottinger (2006):''
 
*''according to Hottinger (2006):''
  
'''PORE''' is a minute tubular perforation traversing a lamellar chamber wall, coated internally by an organic sheathe. Subdivided by organic discs ("pore plate" auct.) and closed off internally by the inner organic lining. The latter may fuse with the basal disc corresponding to the median layer and form an organic pore plug. The size and shape of the external and internal pore openings may be identical (rounded to elongated) or dissimilar, when symbionts are positioned in egg-holders below the pore mouths for gas exchange. Ultrathinsections of living benthic foraminifera that show in the TEM some cytoplasm in pores are considered to be artefacts due to imperfect preparation. Compare: parapores; pits.
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'''PORE''' is a minute tubular perforation traversing a lamellar chamber wall, coated internally by an organic sheathe. Subdivided by organic discs ("pore plate" auct.) and closed off internally by the inner organic lining. The latter may fuse with the [[basal disc]] corresponding to the [[median layer]] and form an organic pore plug. The size and shape of the external and internal pore openings may be identical (rounded to elongated) or dissimilar, when symbionts are positioned in [[egg-holder]]s below the pore mouths for gas exchange. Ultrathinsections of living benthic foraminifera that show in the TEM some cytoplasm in pores are considered to be artefacts due to imperfect preparation. Compare: [[parapores]]; [[pits]].
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==References==
 
==References==
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Billman, Hottinger & Oesterle (1980), Neogene to Recent Rotaliid Foraminifera from the Indopacific Ocean; their canal system, their classification and their stratigraphic use, Schweizerische Paläontologische Abhandlungen, Basel, N° 101, p. 71-113.
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Hottinger (1997), Shallow benthic foraminiferal assemblages as signals for depth of their deposition and their limitations, Bulletin de la Société géologique de France, Paris, vol. 168, N° 4, p. 491-505. 
  
 
Hottinger (2006), [http://paleopolis.rediris.es/cg/CG2006_M02/index.html Illustrated glossary of terms used in foraminiferal research]. [http://paleopolis.rediris.es/cg/uk-index.html Carnets de Géologie], [http://paleopolis.rediris.es/cg/CG2006_M02/index.html Memoir 2], ISSN 1634-0744.
 
Hottinger (2006), [http://paleopolis.rediris.es/cg/CG2006_M02/index.html Illustrated glossary of terms used in foraminiferal research]. [http://paleopolis.rediris.es/cg/uk-index.html Carnets de Géologie], [http://paleopolis.rediris.es/cg/CG2006_M02/index.html Memoir 2], ISSN 1634-0744.
 
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Leutenegger (1977), Ultrastructure de Foraminifères perforés et imperforés ainsi que de leur symbiotes, Cahiers de Micropaléontologie, Paris, fasc. 3-1977, 52 p. + 54 pls. 
 
                    
 
                    
  
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Latest revision as of 08:49, 7 May 2019