Electron microscopic observations of human sperm whole‐mounts after extraction for nuclear matrix and intermediate filaments (NM‐IF)

Abstract

The extraction for nuclear matrix and intermediate filaments (NM-IF) is used to reveal, isolate and study these highly resistant structures in different cell types. We applied for the first time this chemical dissection to human spermatozoa and observed them as whole-mounts by unembedded electron microscopy. The general appearance of NM-IF extracted sperm cells was preserved, showing the intermediate filament-like properties of their cytoskeletal components. In most heads, a network was observed in subacrosomal position, consisting of hubs interconnected by filaments. It seemed to be overlaid on another, finer network. The neck retained its integrity, allowing observations of the three-dimensional structure of the segmented columns. More distally, axoneme and outer dense fibres were covered by submitochondrial cytoskeleton in the middle piece and fibrous sheath in the principal piece, with the annulus usually detached from the fibrous sheath. End piece microtubules were retained in most cells and showed a tendency of cohesion, remaining in a parallel bundle or forming flat sheets. In conclusion, our results provided additional structural details of human sperm cytoskeleton and demonstrated the advantages of combining different methodological approaches in ultrastructural research.

Human FAM154A (SAXO1) is a microtubule-stabilizing protein specific to cilia and related structures

“…2C). Furthermore, colocalization of tubulin and hSAXO1 occurs at the distal end of the flagellum, a region that is devoid of para-axonemal structures and where MTs can form a broom-like structure or fibrils (Markova, 2004;Pease, 1963). Interestingly, hSAXO1 immunofluorescence labeling appeared also as a dot next to the proximal end of the flagellum, corresponding to the proximal centriole.…”

Spatial Distribution of Actin and Tubulin in Human Sperm Nuclear Matrix‐intermediate Filament Whole Mounts—A New Paradigm

“…Nuclear Matrix-Intermediate Filament Preparation Nuclear matrix-intermediate filament (NM-IF) preparation of sperm samples (n ¼ 8) was carried out as reported (Markova, 2004). All the incubations were at 48C unless specified.…”

“…3a); however, the underlying surface characteristics could not be resolved. The anterior portion of the sperm head showed the presence of periodic hub-like (Markova, 2004) raised structures at 100 kV, 490003 (Fig. 1).…”

“…The cytoskeletal proteins earlier viewed as dots in two-dimensional images gained a third dimension but left the correlation between these dimensions to the imagination of the viewer. Recent and important study by Markova (2004) bridged this gap and enabled comprehension of the sperm cytoskeleton in terms of the filament system. However, the biochemical identity of this filament system remained unresolved.…”

Ultrastructural alterations of frozen‐thawed Asian elephant (Elephas maximus) spermatozoa

“…Although the use of fluorescent probes is an excellent technique for evaluating biological function of spermatozoa, ultrastructural studies of thin sections using electron microscopy (EM) can provide more detailed information on the subcellular structure (Barthelemy et al. , 1990; Markova, 2004; Nishizono et al. , 2004).…”