chromosomes
The Chromosomal Theory of Inheritance was consistent with Mendels laws and was supported by the following observations: During meiosis, homologous chromosome pairs migrate as discrete structures that are independent of other chromosome pairs. The sorting of chromosomes from each homologous pair into pre-gametes appears to be random. Each parent synthesizes gametes that contain only half of their chromosomal complement. Even though male and female gametes sperm and egg differ in size and morphology, they have the same number of chromosomes, suggesting equal genetic contributions from each parent. The gametic chromosomes combine during fertilization to produce offspring with the same chromosome number as their parents.