# Flexible-Imaging-Fiber-Guided Intrratracheal Intubation in Rodents
## 4 Discussion  
The precise administration of drugs and toxic substances is essential to accurately evaluate their effects in animal models. Traditional methods of drug administration, such as oral gavage or intraperitoneal injection, can result in variability in dosing and may not accurately reflect the intended target site. In recent years, a small endoscope has been developed to  
Figure 4: Histopathological analysis of lungs in each group. (**A**) A histopathological section of a mouse lung treated with PHMG shows inflammatory cells infiltrating the alveoli (H&E, X200), (**B**) a tissue section of mouse lung treated with PBS, which serves as a negative control (H&E, X200), (**C**) the control group, which did not receive any treatment (H&E, X200) in the mouse model. Figure 5: Histopathological analysis of lungs in each group. (**A**) A histopathological section of a rat lung treated with PHMG shows inflammatory cells infiltrating fibrosis (H&E, X200), (**B**) a tissue section of rat lung treated with PBS, which serves as a negative control (H&E, X200), (**C**) the control group, which did not receive any treatment (H&E, X200) in the rat model. precisely administer drugs and toxic substances in small animal models [20; 21; 22]. In this discussion, we will evaluate the advantages and limitations of using a small endoscope for accurately administering drugs and toxic substances in small animal models. Accurate drug administration and precise substance control are vital for the successful design of animal disease models and toxicity evaluation. Various studies have reported intratracheal administration of drugs in rodents. According to [PERSON] et al., a 90% success rate was achieved when constructing an animal model using an automatic video intratracheal drug administration system, where the administration was reported to be possible with an operating time of approximately 1 min [20]. However, a rigid intratracheal drug administration system may provide sufficient images and a suitable route for drug injection in rats. In the case of mice, a smaller and more convenient device is required, considering the narrow intratracheal site and oral structure. Repeated administration in mice should be accompanied by convenient use by the researchers. There are no reports on the administration of flexible fiber imaging with soluble and powdered substances in any of the previously reported equipment. In this study, a system that can administer powder-type formulations is also one that can be administered to the lungs through an air pump through the powder chamber through the upper respiratory tract. This study developed a system that can inject a certain amount of liquid and powdered substances with a flexible imaging guide in a microstructure organ than reported systems for intubation. In particular, a system with an outer diameter of less than 2 mm with the fusion of a small imaging probe under 1 mm and a drug injection tip has yet to be reported. Based on these results, the system confirmed 100% administration of toxins to lung lesions in animals such as mice and rats, allowing quantitative administration directly through the airway. In this study, we evaluated the accuracy of the administration to intratracheal while using only one gender. In the future, we plan to conduct a large-scale survey to identify the response of males and females for toxicity evaluation studies using new toxic substances. One of the major advantages of using a small endoscope for drug administration is that it allows for precise targeting of the intended site. The use of a small-sized endoscope allows for accurate dosing of the drug or toxic substance. With real-time imaging, researchers can visually confirm the drug's or toxic substance's placement, ensuring precise dosing. Additionally, the use of a small endoscope can reduce variability in drug administration. Traditional methods of drug administration, such as oral gavage or intraperitoneal injection, can result in variability in dosing due to differences in absorption rates or metabolism.