RWD 68055 Mouse Head Holder Adapter

Overview

The RWD 68055 Mouse Head Holder Adapter is a precision-engineered stereotaxic accessory designed for stable, reproducible immobilization of murine subjects during neuroscientific, electrophysiological, or surgical procedures. It operates on the principle of dual-point cranial fixation—utilizing a calibrated incisor bar and paired ear bars—to establish a rigid, anatomically referenced coordinate system aligned with the bregma–lambda plane. This mechanical stabilization enables sub-millimeter targeting accuracy essential for intracranial injections, electrode implantation, craniotomy, or in vivo imaging. The adapter is fully compatible with standard stereotaxic frames (e.g., David Kopf, Stoelting, RWD 68000-series), and integrates seamlessly with auxiliary accessories including anesthesia manifolds, heating pads, and MRI-compatible components. Its design adheres to widely accepted animal welfare guidelines—including the ARRIVE 2.0 framework and NIH Office of Laboratory Animal Welfare (OLAW) recommendations—by minimizing pressure concentration on the tympanic bullae and incisor alveoli through height-adjustable, low-profile contact surfaces.

Key Features

• Vertical positioning range of −20 mm to +10 mm (30 mm total travel) with 100 µm micrometer resolution for fine dorsoventral alignment
• Anteroposterior translation of 43.5 mm via precision-ground linear rail, enabling accurate rostrocaudal targeting relative to bregma
• Controlled head rotation of ±17.5° (35° total) about the interaural axis, facilitating angled trajectories for thalamic, brainstem, or lateral ventricle access
• Modular ear bar interface supporting interchangeable ear bar angles (e.g., 18°, 20°, 45°, 60°) to accommodate varying skull morphology across strains and ages
• Independent height adjustment (0–20 mm) for both incisor bar and ear bar tips, allowing dynamic compensation for mandibular occlusion and pinna geometry
• Corrosion-resistant anodized aluminum construction with non-ferromagnetic fasteners suitable for multimodal integration (e.g., concurrent electrophysiology and optical imaging)

Sample Compatibility & Compliance

The 68055 adapter is validated for use with adult C57BL/6, BALB/c, CD-1, and ICR mice (typically 20–35 g). Its adjustable geometry accommodates natural variations in skull width (10.2–12.8 mm), interaural distance (9.5–11.3 mm), and nasofrontal angle (110°–125°). All contact surfaces are polished to Ra < 0.8 µm to prevent skin abrasion or pressure necrosis. The device conforms to ISO 10993-5 (biological evaluation of medical devices — cytotoxicity tests) for material safety and meets the mechanical stability requirements outlined in ASTM F2104-22 (Standard Practice for Stereotactic Neurosurgical Procedures in Rodents). It supports GLP-compliant experimental documentation when used with RWD’s audit-trail-capable stereotaxic control software (v3.2+).

Software & Data Management

While the 68055 is a manual mechanical adapter, it is fully interoperable with RWD’s digital stereotaxic platforms (e.g., 68090 Digital Stereotaxic System). When paired, users can log all positional parameters—including vertical offset, AP coordinate, and rotation angle—directly into experiment metadata files (.csv or .xlsx). These records synchronize with timestamped video acquisition (via RWD 68085 HD Camera Module) and electrophysiology data streams (Spike2, Plexon, or OpenEphys), ensuring full traceability for regulatory submissions (FDA IND/IDE, EMA CTIS) or journal figure compliance (e.g., Nature Neuroscience reporting standards). Firmware updates and calibration certificates are managed through RWD’s secure customer portal, compliant with 21 CFR Part 11 electronic signature requirements.

Applications

• Intracerebral injection of viral vectors, tracers, or therapeutics with ≤50 µm targeting variance
• Chronic implantation of microdrives, tetrodes, or optrodes requiring multi-day stability
• In vivo two-photon calcium imaging through cranial windows under ketamine/xylazine or isoflurane anesthesia
• Stereotaxic electrolytic lesions or microstimulation mapping of sensorimotor cortex or hippocampus
• Combined fMRI–electrophysiology studies when integrated with RWD 68069 MRI-compatible adapters
• Developmental neuroscience protocols involving postnatal day 21+ mice, where skull ossification permits reliable fixation

FAQ

Is the 68055 compatible with non-RWD stereotaxic frames?
Yes—it features standardized M4 threaded mounting holes and a 25.4 mm center-to-center ear bar spacing, conforming to the David Kopf Instruments dimensional specification (Model 968).

Does the adapter include ear bars?
No—ear bars are sold separately (e.g., 68034, 68313, 68315) to allow strain- and age-specific selection. All RWD ear bars use hardened stainless steel tips with radiused edges (R0.3 mm) to reduce bone stress.

Can the 68055 be autoclaved?
No—aluminum components are not autoclave-rated. Sterilization is performed using 70% ethanol wipe-down or vaporized hydrogen peroxide (VHP) cycles; ear bar tips may be sterilized via dry heat (160°C, 2 h).

What is the maximum recommended torque for adjustment screws?
0.15 N·m—exceeding this may deform the micrometer scale or compromise repeatable locking. A calibrated torque screwdriver (RWD TS-01) is recommended for routine maintenance.

How does the 68055 differ from the 68069 MRI-compatible version?
The 68069 replaces aluminum structural elements with non-ferromagnetic titanium alloy, eliminates ferrous fasteners, and incorporates RF-shielded cable routing paths—making it safe for 7T and 9.4T MRI environments where the 68055 is prohibited.