A wall of tissue dividing the two thecas can be observed in this image of an anther. Each theca contains two pollinic sacs separated by a layer of tissue. Histologically, the anther shows an epidermis referred as exotecium, followed by a layer of large cells known as endotecium. The endotecium is involved in theca dehiscence. The four pollinic sacs contain the microspores that become pollen grains, which are observed in this image. The tapetum is a layer of multinuclear cells that covers the inner surface of the pollinic sac and it is involved in nurturing during the pollen grains formation. Between the thecas, there is the connective tissue continuous with the stamen filament. The filament (not visible in this image) links the anther to the receptacle and consists of parenchyma with vacuolated cells surrounding a central vascular bundle.