Sexual spores are structures generated from meiosis with ploidy (number of chromosomes) reduction to a half compared to the spore mother cell. Spores germinate and give existence to gametophytes, individuals that by mitosis form gametes. The meiosis that generates sexual spores is called sporic meiosis; it is, for example, the type of meiosis that occurs in plants.

Gametes are also cells with half the number of chromosomes of the normal cell of the species, but they are specialized in fecundation, the fusion with another gamete that generates the zygote, a cell with double the number of chromosomes than gametic cells.
Gametes can appear from gametic meiosis or by mitosis in gametophytes originated from sexual spores.

In humans as well in most animals the meiosis is gametic. There are no spores nor alternation of generations. The male gamete is the sperm cell, and the female gamete is the egg cell.   _{Your Comment}