Data/hora: 10/06/2024 03:34:00

Provedor de dados: 	16	
País: 	Netherlands	
Título: 	A comparative ultrastructural study of pit membranes with plasmodesmata associated thickenings in four angiosperm species	
Autores: 	Rabaey, D.; Lens, F.; Huysmans, S.; Smets, E.; Jansen, S.	
Data: 	2008	
Ano: 	2008	
Palavras-chave: 	Ontogeny; Pseudo-torus; Tracheary element; Pit membrane; Bordered pit; Wood ultrastructure; 42.56.	
Resumo: 	Recent micromorphological observations of angiosperm pit membranes have extended the number and range of taxa with pseudo-tori in tracheary elements. This study investigates at ultrastructural level (TEM) the development of pseudo-tori in the unrelated Malus yunnanensis, Ligustrum vulgare, Pittosporum tenuifolium, and Vaccinium myrtillus in order to determine whether these plasmodesmata associated thickenings have a similar developmental pattern across flowering plants. At early ontogenetic stages, the formation of a primary thickening was observed, resulting from swelling of the pit membrane in fibre-tracheids and vesselelements. Since plasmodesmata appear to be frequently, but not always, associated with these primary pit membrane thickenings, it remains unclear which ultrastructural characteristics control the formation of pseudo-tori. At a very late stage during xylem differentiation, a secondary thickening is deposited on the primary pit membrane thickening. Plasmodesmata are always associated with pseudo-tori at these final developmental stages. After autolysis, the secondary thickening becomes electron-dense and persistent, while the primary thickening turns transparent and partially or entirely dissolves. The developmental patterns observed in the species studied are similar and agree with former ontogenetic studies in Rosaceae, suggesting that pseudo-tori might be homologous features across angiosperms.	
Tipo: 	Article / Letter to the editor	
Identificador: 	http://www.repository.naturalis.nl/record/430078

http://www.repository.naturalis.nl/document/457488	
Formato: 	application/pdf	
Fonte: 	Various articles (1612-6102) vol.33 (2008) p.255	
Fonte: 	(c) Naturalis