Liquid-base cytology: a new method for oestral cycle study in wistar's rats

Abstract

OBJECTIVES: The objective of this study was the standardization of a collection technique and staining in liquid-base that allies the pratical and cytological wealth, making possible a larger reproductibility and microscopic easiness. METHODS: Female wistar rats (n=20) were submitted to the daily vaginal collection in saline and fastened washed (ether/alcohol) and stained in suspension with a solution of Evans Blue 0.025%. The sample was pondered by centrifugation and observed under lens of 40 x. RESULTS: The stained smears allowed clear differentiation of the phases of hormonal cycle (diestrus, proestrus, estrus and metestrus); besides the differentiation of the cellular types in relation to its maturation degree having as parameters the cellular size, nucleus / cytoplasm relationship (NCR) and ink reaction. The study demonstrated the existence of three basic cellular patterns: cells with low NCR, accentuated cyanophily and small size; cells with increment in NCR, cyanophilic loss and larger volume cytoplasmatic and without nuclei keratinization cells in squamous aspect. CONCLUSION: The staining of the material allowed, besides the cytological classification, the quantification possibility that would result in a perfected accompaniment of the cycle estrous.