India ink: a time-tested histological marker

India ink: a time-tested histological marker

“…Figure 1 from Szerb et al 1 corresponds well with our figure 1A 2. Both were captured at low magnification.…”

“…Responding to the type of extrafascicular intraneural injection that Dr Szerb’s group illustrates in their figure 1,1 we have to point out that this was also demonstrated by our group for interscalene, supraclavicular, and infraclavicular regions (unpublished data) and, of course, the India ink, as well as the new marker, do not cross the epineurium. Furthermore, these markers do not diffuse through the perineurium 6 7.…”

“…The use of our new marker most likely facilitated this new finding described above because each particle of the erythrocyte marker can be separated from one another due to the high doses of heparin. Images with India ink are almost always shown at low magnification, as in the authors’ figures 1 and 2 1. It is, thus, very possible to observe many complete fascicles.…”

“…We appreciate the interest of Dr Jennifer J Szerb and her team1 in our paper on the use of heparinized diluted blood to study intraneural injection. We were, however, surprised that the focus of their criticism was on the use of the marker and not on the subject of our letter 2.…”

“…For many decades, India ink has been used by pathologists and surgeons to mark the margins for surgical resections. We never disputed the use of India ink to investigate issues related to intraneural injections or to identify the microscopic anatomical location of the needle tip position following the use of high-frequency surface ultrasound 1. We merely looked for new and better alternative markers to explore new ways and gain new insight, into the events related to intraneural injections that until now had eluded us.…”