Question

What is Syngamy?

Answer 1

Syngamy is defined as the fusion of two gametes$(n)$ with each other to form a newly developed zygote $(2n)$ . Here, $(n)$ represents the number of chromosomes i.e. haploid $(n)$ or diploid $(2n)$. Syngamy is a crucial phase in sexual life cycle and initial development of a living cell.

Complete Answer:
Generally, syngamy can be referred to as the process of fusion of two living cells (gametes) to form a newly developed cell (zygote) with twice the number of chromosomes. Syngamy can also be defined as the fusion of a male gamete $(n)$ with a female egg $(n)$ to form the zygote $(2n)$ . It is also called true fusion or first fertilization. Moreover, syngamy is broadly categorized into three types:
i) Isogamy: It is a type of sexual reproduction which involves fusion of gametes which are identical in shape and size. In such cases, the identification of male gamete and female gamete becomes very difficult.
ii) Heterogamy: It is a type of sexual reproduction which involves fusion of gametes of different sizes. Moreover, the differentiation amongst the gametes is done based on the distribution of work. Typically the female gametes are found to be larger than the male gametes, however the number of male gametes is more than the female gametes.
iii) Oogamy: In this type, the mobility of the gametes varies from each other. The female gamete is called an oocyte and it is non-motile, whereas the male gamete is called spermatozoon and is motile.

Note: The angiospermic plants exhibit a distinct characteristic of double fertilization. During double fertilization, initially two nuclei (sperm nuclei) from individual pollen tubes fertilize with the two cells in an ovary. Later on, one of the sperm nuclei fuses with one of the egg cells and forms a zygote $(2n)$, leading to development of embryo at final stage. This union is referred to as syngamy or fertilization.