A Comparison of Anther Tissue Development in Male Sterile Aloe vera and Male Fertile Aloe ciliaris

Cytological differences between the anther development of a male sterile and a male fertile Aloe species are used to explain interactions between anther tissues. Some deviations in the layers of the locule wall and the microspores of the male sterile anther are related to each other and their biological functions are discussed. The cytological development of the male sterility, which can be observed shortly after meiosis, seems to be restricted to the locular cavity. The tapetal development and breakdown are normal, apart from the size of some orbicules. However, the pollenkitt is not transported to the pollengrains, which strongly supports our theory that this process is mechanically pollen-controlled. The development of the epidermal and endothecial cells is normal, except in a part of the anthers where these cells do not expand, after which dehiscence is incomplete. The latter process is discussed in relation to the deviations inside the locular cavity.