Pollen development in male-fertile and cytoplasmic male-sterile rye

Pollen development in a male-fertile and a cytoplasmic male-sterile line of rye (Secale cereals L.) was investigated using histological techniques. In the male-fertile line a high degree of organization was evident within the locule, and polarity within the microspore was also apparent. In the male-sterile line, development appeared to proceed normally until the tetrad stage. Just after tetrad breakup, the tapetum became vacuolate and invaded the locule. Two days later the organization within the locule had broken down completely. Microspores and tapetum had become an unorganized mass within the locule. By 10 days after tetrads, the middle layer had also broken down. At dehiscence the contents of the locule remained as a compressed layer over the endothecium of the anther.