**1.8 Limitation of mice as an ideal model of human physiology and disease**

When comparing mice and humans, there are several variances in developmental timing and reproductive organ shape, as well as discrepancies in their metabolism. Poly-ovulation and a brief period of gestation period in mice, for example, are important variations from humans. Unlike humans, mice are multiparous species such that exposure to endocrine disrupting compounds during gestation has complicated effects on the offspring. Morley-Fletcher and colleagues [20] showed that during sexual differentiation, exposure to sex steroids gave varied results relative to hormone exchange between the female and male fetuses in mice uterine horns.

There are further differences in reproductive function to consider when comparing humans to other mammals like mice. Human oogenesis determinants, for example, are far more intricate than those of most other mammalian species, including mice. When it comes to studying human reproductive disorders, rodent species/ strains have several important limitations. Except in rare strains with certain genetic backgrounds, there are still no germ cell tumors (primary ovarian tumors) in the ovaries of mice or rats; yet it is a common human malignancy in young adult females [21]. It's also worth noting that the outcomes responsive to the effect of repro-toxicants differ amongst mice and rat strains even within the same species. In responding to in utero exposure to a particular phthalate (dibutyl phthalate (DBP)), Wistar rats show elevated incidence of cryptorchidism and reduced rates of epididymal hypoplasia than Sprague-Dawley rats [21].
