INTRODUCTION
Histology is the study of cells and tissues by using a light microscope. The ability to visualize or identify histological structures is frequently enhanced through the use of histological stains. They give contrast to the tissue as well as highlighting particular features of interest. There are two types of dyes that classified by their origins, synthetic and natural dyes. The natural dyes are obtained from natural sources such as plants, insects, animals, clays and minerals (Carleton et al., 1976).
Stains may be used to define and examine bulk tissues (Highlighting, for instance, muscle fibers or connective tissues) cell populations, classifying different blood cells or organelles within individual cells (Penney et al., 2002). Plants and insects known to be used in histological staining for animal tissues are Haematoxylon campechianum (logwood), from which haematoxylin stain is obtained and Dactylopius cacti, from which carmine stain is obtained (Egbujo et al., 2008), respectively. The majority of natural dyes are extracted from plant parts such as roots, barks, leaves, berries and seeds and wood.
Henna (Lawsonia inermis) is a plant, which grow wild in abandoned areas (Muhammad and Mustapha, 1994). It is widely known as cosmetic agent used to color hair, skin and nails (Hanna et al., 1998). Henna has many traditional and commercial uses, the most common being as a dye for hair, skin and finger nails, as a dye and preservative for leather and cloth, and as an antifungal agent. Its flowers have been used to create perfume since ancient times (Bosoglu et al., 1998). It was used as a hair dye in India around 400CE (Auboyer, 1965), in Rome during Roman Empire and in Spain during Covivienca (Fletcher, 1992). Henna produces a red orange dye molecule, “lawsoneâ€Â, which is known as hennotannic acid, that has an affinity for bonding with protein and this has been used to dye skin, fingernails, hair, leather, silk and wool (Singh et al., 2005). But ironically, despite all these dyeing potentials of Henna extracts, they have not being reported to been use as biological stain especially as an alternative stain in to Hematoxylin and Eosin staining technique.
Achiote (Bixa orellana) is a shrub or small tree originating from the tropical region of the Americas. North, Central and South American natives originally used the seeds to make red body paint and lipstick. For this reason, the achiote is sometimes called the lipstick tree.  Annatto is a pigment produced from the seed of the achiote tree (Bixa orellana). Annatto is commonly used as a coloring agent for pharmaceutical ointments and plasters. It contains the pigment bixin, which is commonly used in the food and cosmetics industries to add yellow or red colors (Rodrigues et al., 2007).
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1.1    RESEARCH PROBLEMS/ JUSTIFICATION
The use of natural dyes which are cheaper, eco-friendly and biodegradable has become a matter of significant important due to the increased environmental awareness and in order to avoid some hazardous synthetic dyes to humans and animals (Eom, et al., 2001). Several synthetic dyes (e.g. dyes with azo bonds nitro- or amino-groups) cause allergic-like symptoms or are carcinogenic (Ratna and Padhi, 2012). Therefore, alternative natural dyes have been currently more interested for their potential use in various purposes. This study therefore was aimed at employing the use of Henna (Lawsonia inermis) leaves extract and Achiote (Bixa orellana) seed extract as alternative stain to hematoxylin and Eosin staining technique.
1.2    AIMS AND OBJECTIVES
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