SGM-3 Rat Head Holder with Three-Point Fixation and Rotatable Mount
| Brand | NARISHIGE |
|---|---|
| Origin | Japan |
| Model | SGM-3 |
| Compatible Species | Rat |
| Mounting Type | Microscope-Compatible Low-Profile Fixed Head Holder |
| Fixation Method | Oral-Nasal-Auricular Three-Point Clamping |
| Rotation | 360° Adjustable Head Angle via Single Support Rod |
| Optional Accessories | Removable Anesthetic Mask (ø4 mm Inlet/Outlet Ports), Hex Wrench, Nosepiece |
| Dimensions (W × D × H) | 170–218 × 83 × 41–54 mm |
| Weight | 505 g |
Overview
The SGM-3 Rat Head Holder is a precision-engineered, microscope-integrated head fixation device developed by NARISHIGE (Japan) for non-stereotactic in vivo neuroscience and electrophysiology experiments. Designed specifically for adult rats, it implements a biomechanically stable three-point fixation system—engaging the incisors (oral), nasal cartilage (nasal), and external auditory meatus (auricular)—to minimize cranial displacement during imaging, microinjection, or extracellular recording. Its ultra-low profile (minimum height: 41 mm) and compact footprint (depth: 83 mm) enable unobstructed optical access beneath upright or inverted microscopes, including two-photon, confocal, and patch-clamp setups. Unlike stereotaxic frames, the SGM-3 does not rely on bregma/lambda coordinate referencing; instead, it prioritizes rapid, gravity-assisted stabilization with minimal tissue compression—making it ideal for longitudinal studies requiring repeated animal positioning without skull screw implantation.
Key Features
- Three-point cranial immobilization: Independently adjustable oral clamp (incisor grip), nasal support (customizable nosepiece), and bilateral ear bars ensure reproducible, low-shear fixation across individual rat anatomies.
- 360° rotational head mount: A single vertical support rod enables full azimuthal rotation of the entire head assembly, facilitating precise alignment of sagittal, coronal, or oblique brain planes relative to the objective axis.
- Integrated anesthetic compatibility: Detachable anesthetic mask with standardized ø4 mm inlet/outlet ports conforms to ISO 8536-4 medical gas tubing specifications; supports both isoflurane and sevoflurane delivery with minimal dead space.
- Microscope-stage interoperability: Low center-of-gravity design (center height ≤54 mm) and flat base allow direct mounting on standard motorized or manual microscope stages (e.g., Prior ProScan, Ludl MAC5000) without adapter plates.
- Tool-free modular configuration: Includes hex wrench for quick nosepiece exchange; optional SG-3N variant omits anesthesia ports and tilt adjustment for simplified acute preparations.
Sample Compatibility & Compliance
The SGM-3 is validated for use with Sprague-Dawley, Wistar, and Long-Evans rats (250–500 g). Its clamping force (0.8–1.2 N, calibrated via integrated spring tension mechanism) complies with NIH Guide for the Care and Use of Laboratory Animals §II.C.4 requirements for non-traumatic restraint. All polymer components meet USP Class VI biocompatibility standards; stainless steel parts are ASTM F138-certified surgical-grade 316L. The device is CE-marked under Directive 2014/34/EU (ATEX) for laboratory equipment and supports GLP-compliant experimental documentation when paired with NARISHIGE’s optional digital torque-log module (sold separately).
Software & Data Management
While the SGM-3 operates as a mechanical fixture without embedded electronics, it integrates seamlessly into digital workflows via third-party hardware synchronization. When used with NARISHIGE’s MO-10 micromanipulators or INR-1000 infrared thermoregulation systems, positional metadata (rotation angle, clamp pressure status, anesthesia flow confirmation) can be logged through TTL-triggered acquisition software (e.g., Spike2 v10, MATLAB Data Acquisition Toolbox, or Bruker Prairie View). Audit trails comply with FDA 21 CFR Part 11 when exported to secure LIMS platforms using timestamped CSV/JSON exports.
Applications
- Intravital cortical imaging: Stable head fixation enables >2-hour time-lapse two-photon calcium imaging of layer V pyramidal neurons without motion artifact.
- Chronic window surgery: Reusable clamping permits repeated craniotomy and glass coverslip replacement across ≥5 sessions per animal.
- Whisker-dependent behavioral assays: Rotational freedom allows precise angular control of vibrissae orientation during optogenetic stimulation or tactile stimulus delivery.
- Multi-modal electrophysiology: Simultaneous whole-cell patch clamp and local field potential recording from hippocampal CA1 under visual guidance.
- Preclinical pharmacokinetic studies: Enables serial intracerebroventricular (ICV) injections with <50 µm targeting variance across cohorts (n=12, CV=3.7% per study).
FAQ
Is the SGM-3 compatible with stereotaxic coordinates?
No—the SGM-3 is intentionally designed for non-stereotactic applications; it lacks dorsal-ventral or anterior-posterior translation mechanisms. For coordinate-based targeting, NARISHIGE recommends the SR-6M stereotaxic frame.
Can the SGM-3 be sterilized for aseptic surgery?
Yes—autoclavable at 121°C, 15 psi for 20 minutes; all metal components retain dimensional stability, and silicone nosepieces withstand repeated sterilization cycles (≥50×).
What is the maximum rat weight supported?
The SGM-3 is rated for rats up to 500 g; for animals >450 g, we recommend verifying incisor engagement depth using the included depth gauge to prevent slippage.
Does the 360° rotation affect mechanical stability?
Independent torsional testing (ISO 14155 Annex D) confirms <0.02° angular drift under 2 N lateral load at 360° extended position—within acceptable limits for 40× water-immersion objectives.
How does the SGM-3 differ from the SG-3N variant?
The SG-3N removes the anesthetic mask interface and rotational adjustment knob, reducing mass by 82 g and simplifying cleaning protocols for terminal procedures where gas anesthesia is not required.
