ScienceAsia 25 (1999) : 181-184 |doi: 10.2306/scienceasia1513-1874.1999.25.181

The Acrosome Reaction of Sperm
from Paphia undulata

Pleanphit Jaroensastraraks^** and Praneet Damrongphol

ABSTRACT: Acrosome reaction (AR) of the sperm from Paphia undulata, the short-necked or baby clam, was induced with high calcium-artificial seawater (containing 0.3 M calcium chloride). Scanning electron microscopy revealed the occurrence of an average of 41.6 % 10.6 sd acrosome-reacted sperm upon the induction. The head of the acrosome-intact sperm consisted of a conical shaped acrosome (0.29 m 0.02 sd long and 0.58 m 0.05 sd diameter) and a conical shaped nucleus (1.29 m 0.08 sd long and 1.28 m 0.05 s.d. diameter). The AR was marked by the initial elongation of the anterior end of the acrosome followed by the rupture of the tip exposing an axial, rod-like, acrosomal process (AP). At the completion of the AR, the fully extended AP (0.51 m 0.04 sd long and 0.16 m 0.01 sd diameter) with a slightly wider base (0.28 m 0.03 sd diameter) surrounded by the empty hull of the acrosome was formed.

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Department of Biology, Faculty of science, Mahidol University, Bangkok 10400, Thailand.

* Corresponding author: Tel: +66-2-246 1358, Fax: +66-2-247 0079

Received 5 March 1999