The biochemical and physical duet of the mother and the fetus in the formation of the placenta is one of the most carefully orchestrated phenomena in fetal development. It represents the cooperation of two distinct individuals to form a single structure that protects one and enables the genes of the other to live on.
This cycle is known as alternation of generations. The spores of seed plants, however, are produced internally and the megaspores, formed within the ovules and the microspores are involved in the formation of more complex structures that form the dispersal units, the seeds and pollen grains.
Cell structure and metabolism. G. stearothermophilus contain endospores which are a highly resistant dormant form of the bacteria. The bacteria produce spores under harsh conditions when nutrient levels are low. The spore core is dehydrated (10-25% water content) making it very resistant to heat and chemicals.