On 2016 Jul 05, STEPHEN ROPER commented:

Despite the impressive technique and the many fine figures in this paper, the findings regarding the microvascular permeability in taste buds (Fig 4) are deeply flawed. Specifically, the authors purport to show that compounds such as fluorescein injected into the blood stream have ready access to the cells within taste buds (Fig. 4g-i). Regrettably, this figure, and specifically Fig 4h, reveals a serious misconception about taste buds. This micrograph shows fluorescein-laden lingual surface epithelial squames surrounding the taste bud pore. It does NOT show taste cells. The taste bud itself lies below this plane of focus. Because the quantification in Fig 4i is taken from Fig 4h, it thus is correspondingly in error. Compounds injected into the bloodstream indeed have ready access to the stratified lingual epithelium, including superficial layers, as shown by a previous publication (Dando et al, 2015, Am J Physiol Cell Physiol. 308:C21-32. Epub 2014 Sep 10).

In fact, contrary to the conclusions reported here, there is some form of selectively permeable barrier protecting taste bud cells from many blood-borne chemicals (ibid.). Indeed, Fig. 4g of Choi et al may be consistent with such a barrier, assuming that the relatively fluorescein-free central area in this micrograph is a taste bud. [It might merely be the somewhat acellular connective tissue core of the papilla. This would also be relatively free of fluorescein].

On 2016 Jul 05, STEPHEN ROPER commented:

Despite the impressive technique and the many fine figures in this paper, the findings regarding the microvascular permeability in taste buds (Fig 4) are deeply flawed. Specifically, the authors purport to show that compounds such as fluorescein injected into the blood stream have ready access to the cells within taste buds (Fig. 4g-i). Regrettably, this figure, and specifically Fig 4h, reveals a serious misconception about taste buds. This micrograph shows fluorescein-laden lingual surface epithelial squames surrounding the taste bud pore. It does NOT show taste cells. The taste bud itself lies below this plane of focus. Because the quantification in Fig 4i is taken from Fig 4h, it thus is correspondingly in error. Compounds injected into the bloodstream indeed have ready access to the stratified lingual epithelium, including superficial layers, as shown by a previous publication (Dando et al, 2015, Am J Physiol Cell Physiol. 308:C21-32. Epub 2014 Sep 10).

In fact, contrary to the conclusions reported here, there is some form of selectively permeable barrier protecting taste bud cells from many blood-borne chemicals (ibid.). Indeed, Fig. 4g of Choi et al may be consistent with such a barrier, assuming that the relatively fluorescein-free central area in this micrograph is a taste bud. [It might merely be the somewhat acellular connective tissue core of the papilla. This would also be relatively free of fluorescein].