Structural abnormalities of common carp Cyprinus carpio spermatozoa

Area of Science:

• Aquatic biology
• Reproductive biology
• Ichthyology

Background:

• Common carp (Cyprinus carpio) spermatozoa typically possess a single flagellum and a primitive head.
• Spermatozoa abnormalities, such as multiple flagella or double heads, were observed during motility evaluations.

Purpose of the Study:

• To investigate the ultrastructure and physiological parameters of abnormal common carp spermatozoa.
• To compare these findings with similar abnormalities reported in livestock.

Main Methods:

• Light microscopy (dark field with stroboscopic illumination)
• Transmission and scanning electron microscopy
• Flow cytometry
• Olympus MicroImage software for analysis

Main Results:

• Abnormal spermatozoa exhibited multiple flagella and/or double heads, with larger heads and shorter flagella.
• Cytoplasmic channels sometimes separated flagella from the midpiece.
• Each flagellum had its own centriolar complex; flagella structure (9+2 microtubule arrangement) was normal.
• Sperm DNA content was similar to normal sperm but with higher variation.

Conclusions:

• Observed sperm abnormalities in common carp suggest defects in spermiogenesis.
• These abnormalities, while documented in livestock, are novel in fish.
• Further research is needed on the frequency, impact on fertilization, and effects on progeny.