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nification (Long & Evans, 1922). They both also recorded that the layers of vaginal mucosa include the stratum corneum, stratum granulosum, rete mucosum and stratum germinativum. As the cells shed off, the vaginal epithelium changed morphologically responded to the cyclic differences in vaginal cytology.

The stages of estrous cycle are identified by the absence, presence or proportion of the described basic cell types as well as the density and arrangement of the cells on the slide. Most cells seen in a normal vaginal smear are vaginal epithelial cells. In some protocols, the vaginal smears have been dry fixed and stained with metachromatic stain to clearly characterize and recognize the type of cells present in the smears.

Many publications and authors came out with different type of cells but indicating to the description of the cells, they were looking at the same cell type but with different names. In Hubscher et al. (2005) and Marcondes et al. (2002), the authors described the epithelial cells as leukocytes, nucleated cells and cornified cells. A round cell with nucleus is named as nucleated cells, an irregular shaped of cell without nucleus is named as cornified cells and leukocytes is a little round cell (Marcondes et al., 2002). Leukocytes are very small, round shape and possess multilobulated nuclei. These cells are also known as neutrophils or polymorphonuclear cells.

On the other hand, Paccola et al. (2013), described 5 types of cells in their works as small basophilic cells (SBC), large basophilic cells (LBC), nucleated acidophilic cells (NAC), enucleated acidophilic cells (EAC) and pre- acidophilic cells (PAC). Basophilic cells were represented less distinct cells from basal layer and intermediate epithelial layers. SBC are rounded shape cells with large nuclei and sparse chromatin while LBC are a polygonal shape cells, displayed condensed chromatin and smaller than SBC. Acidophilic cells are from superficial layers and more distinct. NAC are polygonal in shape and had small nuclei while EAC are keratinized cells without nucleus as they moved to the superficial layers. PAC are enucleated small cells and polygonal in shape that are partly keratinized.

On top of that, these three remarkable publications had improvised the protocols of staging and identifying of cells in vaginal smears. NAC, EAC and PAC descripted as cornified cells while on the other hand SBC and LBC descripted as nucleated cells. Paccola et al., (2013), the most recent publication had revised and improvised the type of cells specifically to characterize the stages of estrous cycle and provide insight of identification protocols.

The estrous cycle is divided into 4 stages which are termed as proestrus, estrus, metestrus, and diestrus. The cycle regularly repeats every 4 to 5 days unless interrupted by pregnancy, pseudopregnancy, or anestrus. The cycle has been described in detail elsewhere in Hubscher et al. (2005), Cora et al. (2015) and Goldman et al. (2007).