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Electron microscopic observations of mouse sperm whole mounts after extraction for nuclear matrix and intermediate
1Department of Biology, Medical Faculty, Medical University of Sofia, Bulgaria. mmarkova@medfac.acad.bg
Abstract:
Nuclear matrix and intermediate filaments (NM-IF) can be isolated by sequential treatment with non-ionic detergent, high salt. and nuclease. Extracted cells are easily observed by unembedded whole-mount transmission electron microscopy. Different somatic cell types have been subjected to this procedure and retained their essential architecture. To our knowledge, this work describes the first application of NM-IF extraction to sperm. After chemical dissection the general appearance of mouse sperm cells was preserved, except for head-from-neck separation in some cases. The cell membrane, acrosome and mitochondria were not present. The nucleus showed no apparent changes and revealed no details excepting pore complexes in the posterior part. Tissue-specific cytoskeletal elements (perforatorium, postacrosomal sheath, capitulum, segmented columns, outer dense fibers, submitochondrial reticulum, annulus, and fibrous sheath) were retained, which permitted a parallel between them and intermediate filaments of somatic cells. Tail microtubules were also relatively well preserved, showing high intrinsic stability. Cell structures could be observed well, with some details in the tail even better visible than in ultrathin sections. Observation of mouse sperm whole mounts after NM-IF extraction not only revealed intermediate filament-like properties of their cytoskeletal elements but also offered an additional viewpoint to sperm ultrastructure.
Insights
Nuclear matrix and intermediate filaments (NM-IF) extraction reveals sperm cytoskeletal elements. This method preserves sperm architecture, offering new insights into sperm ultrastructure and intermediate filament-like properties.
Area of Science:
- Cell Biology
- Sperm Biology
- Biochemistry
Background:
- Nuclear matrix and intermediate filaments (NM-IF) are crucial cellular structures.
- Current methods for studying NM-IFs in somatic cells are established.
- Sperm ultrastructure and cytoskeletal elements remain areas for detailed investigation.
Purpose of the Study:
- To apply NM-IF extraction techniques to mouse sperm for the first time.
- To investigate the preservation and characteristics of sperm cytoskeletal elements after NM-IF extraction.
- To compare sperm cytoskeletal elements with intermediate filaments in somatic cells.
Main Methods:
- Sequential treatment of mouse sperm with non-ionic detergent, high salt, and nuclease to isolate NM-IFs.
- Observation of extracted sperm using unembedded whole-mount transmission electron microscopy.
- Analysis of retained cytoskeletal structures and nuclear morphology.
Main Results:
- NM-IF extraction successfully preserved the general architecture of mouse sperm.
- Key sperm cytoskeletal elements, including the fibrous sheath and outer dense fibers, were retained.
- The nucleus remained largely unchanged, with pore complexes visible in the posterior part.
- Tail microtubules demonstrated high intrinsic stability and were well-preserved.
- Some structures were more clearly visualized than in traditional ultrathin sections.
Conclusions:
- Sperm cytoskeletal elements exhibit intermediate filament-like properties.
- NM-IF extraction provides a valuable method for studying sperm ultrastructure.
- This technique offers a novel perspective on the stability and organization of sperm structures.