The passage describes reproduction and early development in mammals. Complete the passage by writing a suitable word or words in each numbered blank space.
During sexual reproduction in mammals, the male gametes, known as (1) _______________, are produced in the testes through a process called (2) _______________. In contrast, the female gametes, or (3) _______________, develop within the ovaries.
If a male gamete successfully penetrates the protective outer layer of the female gamete, (4) _______________ occurs, resulting in the fusion of their haploid nuclei. This process restores the diploid number of chromosomes and forms a single cell called a (5) _______________.
This single cell then travels along the (6) _______________ towards the uterus, undergoing a series of rapid mitotic divisions known as (7) _______________. This division forms a solid ball of cells called a morula, which further develops into a hollow ball of cells called a (8) _______________.
Upon reaching the uterus, this structure embeds itself into the thickened uterine lining, a process called (9) _______________. The outer cells of this structure will eventually go on to help form the (10) _______________, which facilitates the exchange of nutrients, waste, and gases between the maternal and foetal blood systems.
