Gametogenesis. As you are already aware gametogenesis refers to the process of formation of the two types of gametes-male and female. Gametes are haploid cells. In some algae, the two gametes are so similar in appearance and hence are called homogametes (isogametes). That it is not possible to categorize them into male and female gametes. However, in a majority of sexually reproducing organisms the gametes produced are of two morphologically distinct types (heterogametes). In such organisms the male gamete is called the antherozoid or sperm and the female gamete is called the egg or ovum.

 Types of gametes : (a) isogametes of Cladophora (b) heterogametes of Fucus (alga) and (c) human beings