The study by Marcondes, Bianchi, and Tanno (2002) focuses on determining the estrous cycle phases in rats, which are characterized by proestrus, estrus, metestrus, and diestrus. The authors aim to provide researchers with a fast and practical method for this determination. They collected vaginal secretions from thirty female rats daily for a month and observed the material under a microscope without staining, using 10x and 40x objective lenses to analyze the cellular types. The method, which includes collecting vaginal lavage, observing the material, and identifying the estrous cycle phase, took 15-20 minutes per rat. The study confirms that the mean duration of the estrous cycle in rats is 4-5 days and provides useful guidelines for researchers, especially those new to the technique.The study by Marcondes, Bianchi, and Tanno (2002) focuses on determining the estrous cycle phases in rats, which are characterized by proestrus, estrus, metestrus, and diestrus. The authors aim to provide researchers with a fast and practical method for this determination. They collected vaginal secretions from thirty female rats daily for a month and observed the material under a microscope without staining, using 10x and 40x objective lenses to analyze the cellular types. The method, which includes collecting vaginal lavage, observing the material, and identifying the estrous cycle phase, took 15-20 minutes per rat. The study confirms that the mean duration of the estrous cycle in rats is 4-5 days and provides useful guidelines for researchers, especially those new to the technique.