Anatomía del fruto de Casimiroa edulis (Rutaceae), "zapote blanco", durante su desarrollo

White sapote is a Mexican fruit valued for its edible sweet pulp and medicinal seeds. In view of the importance that this species has for Mexico, and considering the scarcity of information on the anatomy of its fruit, a study of its development from flowering to maturity was undertaken. The material was studied by sectioning and maceration. General and staining with safranin and fast green, as well as specific staining for starch, lipids, phenols (tannins) and lignin, were made. The fruit growth in diameter presents a simple sigmoid growth curve. The fibrous structure covering the seed is an endocarp originating from a) the multiple internal epidermis, b) subepidermal layers of fundamental tissue and c) a net of vascular tissue surrounding the locule. The walls of this tissue thicken and lignify just before maturity. The pericarp does not accumulate starch during growth; at maturity it is sweet and contains abundant spherosomes (lipid droplets). The pericarp is populated by numerous lysigenous oil glands presenting various shapes and sizes (0.1-5.0 mm), with their axes radially oriented. We did not find the external hypodermis reported by Schroeder.