Fine structure of spermatozoa of the Asiatic musk shrew, Suncus murinus

Area of Science:

• Reproductive Biology
• Spermatozoa Ultrastructure
• Mammalian Reproduction

Background:

• The Asian musk shrew (Suncus murinus) is a valuable model organism for reproductive studies.
• Understanding spermatozoa fine structure is crucial for reproductive biology and fertility research.

Purpose of the Study:

• To investigate the detailed fine structure of Suncus murinus spermatozoa.
• To characterize the acrosome and associated membrane structures.
• To explore potential methods for acrosome removal.

Main Methods:

• Utilized critical-point-dried and air-dried replicas for electron microscopy.
• Employed freeze-fracture and freeze-etching techniques to examine membrane structures.
• Observed spermatozoa using light microscopy on gelatin smears.
• Attempted physiological and enzymatic incubation for acrosome removal.

Main Results:

• Critical-point-dried replicas revealed subtle dorsoventral head asymmetry, especially in the acrosome, not visible in air-dried specimens.
• Freeze-etching showed a dense accumulation of intramembranous particles anterior to the posterior ring.
• Light microscopy of gelatin smears indicated a vigorous lytic response.
• Preliminary acrosome removal attempts through incubation were unsuccessful.

Conclusions:

• Suncus murinus spermatozoa exhibit distinct head and acrosome asymmetry, best visualized with critical-point-drying.
• Specific intramembranous particle distributions were identified in the head region.
• The acrosome of Suncus murinus spermatozoa is resistant to current physiological and enzymatic removal methods.