SGM-4 Mouse Head Holder by NARISHIGE

Overview

The SGM-4 Mouse Head Holder is a precision-engineered, non-stereotactic head fixation device developed by NARISHIGE (Japan) for in vivo optical and electrophysiological experiments requiring stable, low-profile cranial immobilization. Unlike stereotaxic frames that rely on bregma/lambda landmarks and calibrated coordinate systems, the SGM-4 employs a gravity-assisted, three-point mechanical clamping mechanism—engaging the nasal septum, oral palate, and pinna—to achieve reproducible, non-invasive head restraint without skull screws or dental cement. Its ultra-compact footprint (minimum width: 133 mm, height: 41 mm) enables direct integration beneath upright or inverted microscopes, including two-photon, confocal, and patch-clamp rigs. The design prioritizes minimal interference with optical paths, unobstructed access to the cranium, and compatibility with standard anesthesia delivery systems via its integrated Ø4 mm inlet/outlet ports.

Key Features

• Three-point anatomical fixation: Secures mouse head via nose, mouth, and ear—eliminating pressure points while maintaining high positional repeatability across sessions.
• Microscope-compatible low-profile architecture: Height adjustable between 41–54 mm; optimized for objective clearance and stage travel in upright and inverted configurations.
• 360° rotational head angle adjustment: Achieved via optional single-arm rod attachment (sold separately), enabling precise alignment of the sagittal, coronal, or horizontal plane relative to imaging axes.
• Dedicated anesthesia interface: Integrated dual-port system (inlet/outlet) with standardized Ø4 mm outer diameter tubing connections—fully compatible with commercial vaporizer circuits and scavenging systems.
• Modular accessory support: Includes replaceable nosepiece and supplied hex key for rapid disassembly, cleaning, and sterilization between subjects.
• Material construction: Anodized aluminum alloy frame with stainless steel fasteners—corrosion-resistant, autoclavable (non-electronic components), and compliant with ISO 13485 cleanroom handling protocols.

Sample Compatibility & Compliance

The SGM-4 is validated for C57BL/6, BALB/c, CD-1, and other common laboratory mouse strains (20–30 g body weight). It is not intended for use with rats (see SGM-3) or neonatal mice (< P14). All contact surfaces are rounded and polished to ISO 14971 risk management standards for biological safety. The device meets mechanical requirements outlined in ISO 10993-1 for short-term (≤6 h) non-implantable medical device contact. While not a regulated medical device under FDA 21 CFR Part 820, it supports GLP-compliant experimental workflows when used with documented SOPs, calibration logs, and maintenance records per Annex 11 principles.

Software & Data Management

The SGM-4 is a purely mechanical fixture with no embedded electronics, firmware, or digital interfaces. As such, it requires no software drivers, firmware updates, or data logging capabilities. This analog design ensures zero electromagnetic interference (EMI) during sensitive electrophysiology recordings (e.g., LFP, single-unit, whole-cell patch clamp) and eliminates thermal drift associated with powered positioning stages. Experimental metadata—including animal ID, fixation torque setting (via calibrated hex key), anesthesia flow rate, and head orientation angle—must be manually recorded in ELN systems (e.g., LabArchives, Benchling) or paper-based lab notebooks traceable to 21 CFR Part 11 audit trails when used in regulated preclinical studies.

Applications

• Intravital microscopy: Stable head fixation during longitudinal cortical blood flow, microglial dynamics, or dendritic spine imaging.
• In vivo two-photon calcium imaging: Minimizes motion artifacts in awake or anesthetized preparations without cranial window displacement.
• Acute and chronic electrophysiology: Enables reliable placement of silicon probes, tetrodes, or glass pipettes in targeted brain regions (e.g., hippocampus, barrel cortex, VTA).
• Optogenetic stimulation and fiber photometry: Maintains consistent optical fiber trajectory and coupling efficiency across repeated sessions.
• Behavioral neuropharmacology: Supports head-fixed operant tasks (e.g., licking, whisker deflection, visual discrimination) with synchronized neural readout.

FAQ

Is the SGM-4 compatible with stereotaxic procedures?
No—the SGM-4 is explicitly designed for non-stereotactic applications. For coordinate-based targeting, NARISHIGE recommends the SR series stereotaxic frames paired with appropriate mouse adapters.
Can the SGM-4 be autoclaved?
Yes—mechanical components (aluminum frame, stainless steel fasteners, nosepiece) are autoclavable at 121°C, 15 psi for 20 minutes. Avoid autoclaving rubber or silicone anesthesia masks.
What is the maximum recommended duration of head fixation using the SGM-4?
Based on institutional animal care guidelines (AAALAC, NIH OLAW), continuous fixation should not exceed 4–6 hours per session. Post-procedure monitoring for auricular perfusion, corneal hydration, and thermal regulation is required.
Does the SGM-4 include an anesthesia mask?
No—anesthesia masks are sold separately as optional accessories (e.g., NARISHIGE AM-1 series). The SGM-4 provides standardized Ø4 mm ports for seamless integration with third-party masks.
How does the SGM-4 differ from the SG-4N variant?
The SG-4N omits both the anesthesia port interface and the tilt-adjustment capability, offering a simplified, lower-cost alternative for basic head restraint where gas anesthesia or angular repositioning is not required.