Study on Degeneration of Unfertilized Aposporous Embryo Sac in Pennisetum squamulatium (Gramineae)

To understand the degeneration of unfertilized aposporous embryo sac in an aposporous species Pennisetum squamulatum, the central cell in the unfertilized embryo sac was characterized ultrastructurally . The most prominent sign of degeneration is that the central cell nucleus produced nuclear vacuoles . These nuclear vacuoles can be classified into singleanddouble- layered types . Single- layered nuclear vacuoles are found in the cytoplasm, while the double-layered are inside the nucleus . There are two ways to produce nuclear vacuoles . One is that the outer membrane of the nuclear envelope distends towards the cytoplasm to form nuclear vacuoles ; and the other is the double-layered nuclear envelope derives vacuoles by depressing inwards . Nuclear envelope types are in relation to the ways they are produced . All nuclear vacuoles absorb cytoplasm or nuclear matrix , and trap organelles such as mitochondria .