When applied extracranially to suture branches of intracranial meningeal nociceptors, BoNT-A inhibithe the mechanical responsiveness of the suture branch but not dural axon.
In the fourth paradigm, we applied BoNT-A (four U) to the extracranial receptive field of the suture branch of naïve meningeal nociceptors and tested its effects on mechanosensitivity of three C- and two Aδ-meningeal nociceptors, and on spontaneous activity of 10 C- and six Aδ-units.
Extracranial application of BoNT-A inhibits mechanical transduction in suture branches of meningeal nociceptors.
The straight fibers extend either from the proximal end of the anterior suture branches to the posterior pole or from the proximal end of the posterior suture branches to the anterior pole.
Specifically, fibers that terminate at the proximal ends of suture branches or at the poles lie entirely within a longitudinal plane and have straight end segments.
The lens pole was fractured as the ends of most surface lens fibers failed to abut and overlap to form the three spherical suture branches.
In this set of experiments we first identified meningeal nociceptors (described above) and then searched for extracranial suture branches by applying electrical and mechanical stimuli to different areas along the superior sagittal and lambdoid sutures.
Scanning electron microscopy (SEM) analysis of 6-month-old wild-type mouse lens revealed normal overlapped fiber cell layers forming three equally long suture branches as a "Y" pattern at the lens pole, which is a characteristic of mice, rats, guinea pigs, cats, dogs and cows lenses [ 44].
Fiber folds and breaks[ 5], multi lamellar bodies[ 6, 7], extracellular space deposits [ 8, 9], malformed or excessive suture sub-branches[ 10], syneresis and micro-phase separation of fiber cytoplasm [ 11- 14] and fiber compaction [ 15- 17] have all been observed in aged human lenses and proposed as potential sources of light scatter contributing to age-related cataract formation.
At the cellular level, one or more structural alterations such as fiber folds and breaks [ 5], multi lamellar bodies[ 6, 7], extracellular space deposits[ 8, 9], malformed or excessive suture sub-branches[ 10] and syneresis and micro-phase separation of fiber cytoplasm [ 11- 14] may be present in aged lens fibers, and would be expected to play a role in the increased age-related scatter.
First, both human and rabbit lenses possess branched suture patterns.
