ELECTRON MICROSCOPIC OBSERVATIONS OF MOUSE SPERM WHOLE MOUNTS AFTER EXTRACTION FOR NUCLEAR MATRIX AND INTERMEDIATE FILAMENTS

Abstract

Nuclear matrix and intermediate filaments (NM?IF) can be isolated by sequential treatment with nonionic detergent, high salt, and nuclease. Extracted cells are easily observed by unembedded wholemount 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.

• Electron Microscopy Filament Matrix Mouse Nucleus Sperm