Lingula anatina -3


Schematic illustration showing the sequential morphological change during the acrosome reaction in Lingula anatina spermatozoa.

1. Intact acrosome. A,acrosome; DC, distal centriole; EDS, electron-dense structure; M, mitochondion; N, nucleus; PC, proximal centriole; SAS, subacrosomal substance.
   
2. Membrane fusion between acrosomal outer membrane and the overlying plasmamembrane occurs.
   
3. Acrosome substance is released through the opening at the anterior region of the acrosome.
   
4. Acrosomal substance has been released and the acrosomal process has begun to elongate.
   
5. Eversion of the acrosomal outer membrane causes the electron-dense structures (EDS)to take an external position.
   
6. The EDS is exposed and the acrosomal process is extending.
   
7. The acrosome reaction is completed following the formation of an acrosomal process. AP, acrosomal process.
   

Brachiopods Past and Present : Edited by Brunton, Cooks and Long.
Taylor & Fransis (London and New York)
pp.40-pp.45, 2001

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