Figure 1.
Cultured mouse primary intestinal epithelial cells under an inverted phase-contrast microscope.
(A) The single crypts obtained with collagenase-hyaluronidase dissociation of mouse small intestine. (B) A few cells gradually migrated out around the crypts after 24 h. (C) The epithelial cells started to grow rapidly after 48 h, and multiple large colonies were formed at day 5. (D) Cells continued to grow until confluence was reached after 9 days.
Figure 2.
Morphological characteristic and Immunofluorescence staining of fetal mouse IECs.
(A) The IECs formed a tightly packed monolayer with typical cobblestone morphology (passage 8). (B) HE staining of IECs. (C) Immunofluorescence staining of IEC cytokeratins, cytokeratin 18 was clearly detected in the cytoplasm of IECs with a green color. (D) No green fluorescence in the cytoplasm of IECs was found and only the nucleus was stained red with propidium iodide (PI) in the negative controls.
Figure 3.
Growth curve of passaged mouse IECs in culture.
The log phase started after day 2 of the lag phase with a sharper inclination.
Figure 4.
Observations on invasion of IECs by Trichinella spiralis infective larvae.
(A) When T. spiralis infective larvae were inoculated onto monolayers of mouse IECs in vitro, the larvae invaded the cells, and their head and body resided in the cytoplasm of the syncytia composed of numerous IECs (showed as arrow). (B) After the removal of agarose, the cell monolayer was stained with propidium iodide (PI) and observed under a fluorescence microscope. Nuclei of the damaged cells were stained intensely and uniformly red, showing the serpentine trail left by the parasite. In contrast, nuclei of the live cells not invaded by the larvae were not stained. (C) After being stained with PI, the cell monolayer was fixed and reacted with rabbit immune sera against T. spiralis ES antigens and FITC-conjugated secondary antibody as described in Materials and Methods. Green fluorescence was found in the cytoplasm of the damaged cells. (D) No fluorescence was found in the cells which were not invaded by the non-activated larvae.
Figure 5.
Hematoxylin-and-eosin (HE) staining and immunofluorescence test (IFT) on the small intestines of mice infected with Trichinella spiralis.
(A) The Kunming mice were orally infected with 300 Trichinella spiralis muscle larvae. After 18 hours, they were killed by anaesthetic inhalation with isoflurane, and their small intestines were fixed in 10% formaldehyde solution. HE staining showed that the larvae located at the crypt-villus junction (showed as arrow). (B and C) Different sections of the larvae at the crypt-villus junction were recognized by sera of the rabbits infected with T. spiralis, and exhibited green fluorescence (showed as arrows). The mouse small intestines exhibited only background red fluorescence (propidium iodide). (D) Longitudinal sections of the larvae (showed as arrows) were found in intestinal crypts (green fluorescence).