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.
The structures of fungi are microscopic and not visible to the naked eye. Some are unicellular like yeast, but most string their cells together in long, thread-like strands called hypha.Most fungi produce an extensive system of hyphae, which may be visible when growing thickly in a mass called mycelium (commonly referred to as mould).Mycelium can be of any size from tiny clusters to massive acre wide systems, which effectively form the feeding and growing body of the fungus.he structures of fungi are microscopic and not visible to the naked eye. Some are unicellular like yeast, but most string their cells together in long, thread-like strands called hypha.