Abstract
Once referred to as “peculiar,” tuft cells are enigmatic epithelial cells. Here, we reasoned that future functional studies could be derived from a complete account of the tuft cell ultrastructure. We identified and documented the volumetric ultrastructure at nanometer resolution (4–5 nm/pixel) of specific intestinal tuft cells. The techniques used were Serial Block-Face (SBF) and Automated Tape-collecting Ultra-Microtome (ATUM) Scanning Electron Microscopy (SEM). Our results exposed a short (~15 µm) basal cytoplasmic process devoid of secretory vesicles. Volume rendering of serial sections unveiled several thin cytospinules (~1 µm). These cytospinules project from the tuft cell into the nuclei of neighboring epithelial cells. Volume rendering also revealed within the tuft cell an elegant network of interconnected tubules. The network forms a passage from the base of the microvilli to the rough endoplasmic reticulum. Based on their location and microanatomy, the tuft cells’ cytospinules, and tubular network, might facilitate the exchange of molecular cargo with nuclei of neighboring cells, and the gut lumen.
Highlights
In 1956, Jarvi and Keyrilainen noted a cell type protruding into the lumen of the mouse stomach
For every 1000 cells in the intestinal epithelium, only four cells are of the tuft type[19]
We previously developed a protocol to correlate fluorescence microscopy with volumetric electron microscopy (Fig. 1A)[18]
Summary
Identifying tuft cells for volumetric electron microscopy. Tuft cells stand out by their prominent tuft of microvilli in electron micrographs. Attempts to render the volumetric ultrastructure of the network have lacked sufficient Z resolution to prove the existence of a network[11] These tubular network was evident in our SBEM and ATUM images (Fig. 4B). These enigmatic structures are less than 30 nm, electron dense, and often intercalated within microvilli or microtubules Their relationship with the tubular passage suggests a path for the tuft cell to exchange molecular cargo with the intestinal lumen (Fig. 4D). The passage from the lumen to the endoplasmic reticulum may serve to facilitate sensing of microbial molecules and secreting cargo into the lumen, whereas the cytospinules represent a potential conduit for targeted delivery of cargo into the nuclei of neighboring epithelial cells (Video 2)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
