Abstract
Study was carried out to evaluate the effect of some ecological factors as photoperiod, nutrition and competition as a negative inter-relation between animals on testis parameters their histological structures by using the five levels of spermatogenic index as an indicator of sexual maturity in MFI strain of albino mice. The first experimental group was reared alone (single strain) i.e. without competitors and in the second experiment the mice were reared with another strain Balb/C (mixed strains) i.e., with competitors. Present study revealed violent and aggressive of individuals behavior in the presence of compitots and retarded the gonadal activity and inhibited sexual efficiency. Exposure to longer photoperiod increased the size of testes and accelerated sexual maturity. Exposure to long photoperiods combined with high level of food,without competitors was considered the best environmental conditions for the earlier sexual maturity of mice. While the sexual maturity was retarded in mice exposed to shorter photoperiod and insufficient food with competitors,which lead to an atrophy in the testes and delay the spermatogenic index at the third level in higher ages. This state was considered unsuitable for the sexual maturity.