TK-1 exosomes home to the small intestine in an α4β7-dependent manner. TK-1 exosomes (30 μg each) were fluorescently labeled with either Exo-Green or Exo-Red, mixed (β7-scr-Green/β7-KD-Red or β7-KD-Green/β7-scr-Red), and injected intravenously into mice. Sixteen hours after injection, recipient mice were euthanized, and organs were harvested for preparation of frozen tissue sections. Microscopic analysis was performed to count exosomes distributed to the tissues. The absolute number of fluorescently labeled exosomes was counted in randomly selected microscopic image fields of tissue samples using identical magnification. Fluorescent spots inside each villus were counted in the small intestines to exclude those exosomes in the regions of external tissues such as the lumen. Fluorescent microscopic analyses were performed by 3 independent examiners in a double-blinded fashion, and the results are expressed as the mean ± SEM. ***P < .001 (vs β7-scr).