Spermatozoids of Microcycas calocoma: ultrastructure

Microcycas calocoma, a monotypic Cuban endemic cycad, differs from other cycads in possessing multiple spermatozoids (up to 16 per pollen tube, in comparison with the usual two). The spermatozoids are characterized further by exhibiting a developmental gradient in complexity and motility, ranging fr...

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Bibliographic Details
Published in:Botanical gazette (Chicago, Ill.) Ill.), 1990-09, Vol.151 (3), p.275-284
Main Author: Norstog, K.J. (Fairchild Tropical Garden, Miami, FL)
Format: Article
Language:English
Subjects:
Biological and medical sciences
CELL DIFFERENTIATION
CELL STRUCTURE
CELL ULTRASTRUCTURE
CYCADACEAE
Cytoplasm
CYTOPLASMIC ORGANELLES
DIFERENCIACION CELULAR
DIFFERENCIATION CELLULAIRE
ESPERMATOGENESIS
ESTRUCTURA CELULAR
Evolution
Flagella
Fundamental and applied biological sciences. Psychology
GAMETE
GAMETES
Gametophytes
GAMETOS
Gyres
Lipids
Microsporocytes
Microtubules
Mitochondria
Morphology, anatomy, histology, cytology
MOUVEMENT
MOVEMENT
MOVIMIENTO
ORGANITE CELLULAIRE
ORGANULOS CITOPLASMATICOS
Plant cytology, morphology, systematics, chorology and evolution
POLEN
POLLEN
POLLEN TUBES
SPERMATOGENESE
SPERMATOGENESIS
Spermatophyta
STRUCTURE CELLULAIRE
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Description
Summary:Microcycas calocoma, a monotypic Cuban endemic cycad, differs from other cycads in possessing multiple spermatozoids (up to 16 per pollen tube, in comparison with the usual two). The spermatozoids are characterized further by exhibiting a developmental gradient in complexity and motility, ranging from well-organized and actively motile first-formed spermatozoids to less well-organized and less motile last-formed spermatozoids. It is thought that this relationship exemplifies evolutionary reduction and represents a primitive stage in male-gamete evolution and that Microcycas, therefore, is the most primitive member of the Zamiaceae.
ISSN:0006-8071
1940-1205
DOI:10.1086/337827