Pollen prior to cytokinesis, whereas in successive microsporogenesis cytokinesis follows. While there may be a continuum with intermediate forms, the type of microsporogenesis has systematic significance. The predominant form amongst the monocots is successive, but there are important exceptions. During microgametogenesis, the unicellular microspores undergo mitosis and develop into mature microgametophytes containing the gametes. In some flowering plants, germination of the pollen grain may begin even before it leaves the microsporangium, with the generative cell forming the two sperm cells. Except in the case of some submerged aquatic plants, the mature pollen grain has a double wall. The vegetative and generative
The X from Outer Space Guilala is finally defeated by jets laden with bombs, which coat it in a substance called "Guilalalium." It causes Guilala to shrink down to its original spore form. The government promptly launches the spore back into space, where it will circle the sun in an endless orbit. "The X From Outer Space" was released in Japan on 25 March 1967. "The X From Outer Space" was never released theatrically in the United States, and was released directly to television by American International Television in 1968. The Criterion Collection released "The X from Outer Space" on DVD in a compilation titled