Morphology of abalone spermatozoa before and after the acrosome reaction

摘要: Spermatozoa of the red abalone, Haliotis rufescens, consist a bullet-shaped acrosome granule (2.5 × 1.1 μm), nucleus (4.2 1.0 midpiece (0.75 1.3 μm) consisting five mitochondria, pair centrioles and series vesicles, flagellum (45 0.25 μm). The large contains two distinct components: (1) an ovoid electron-dense body in anterior apex (approximately 0.9 (2) less dense, homogeneous material at posterior. A bundle preformed actin filaments (about 2.4 μm length) protrude from anteriorly located nuclear fossa into acrosomal posterior granule. reaction sperm can be triggered by 30 mM Ca2+ sea water, ionophore A23187, or aging sperm. Upon reaction, releases water-soluble components (thought to electron-dense, granule, leaving ghost-like empty sac with wall approximately 0.03 thickness. extension actin-cored process occurs immediately after exocytosis (7 length 0.2 width) extends through sheath-like ghost inner surface is studded globules 0.04 diameter). outer coated dense which may function sperm-egg adhesion. Abalone are “primitive” type morphology.