Complete cross-section of the anther observed with the objective of 4x. The anther is formed by two thecas, united by a connective and maintained by the filament. Within each theca, there are two pollen sacs containing numerous grains of pollen, which can be thrown out through an orifice or operculum (open in this image). Going from outside inwards the wall of the anther is formed by the following layers: epidermis, mechanical layer, and intermediate layers. In the connective we can observe a vascular bundle, surrounded by parenchyma. Details of the pollen sacs, the filament and a pollen grain are observed at higher magnification in other microphotographies (zones framed in red, blue, and brown, respectively)