Assisted human reproduction (AHR) currently solves numerous difficulti
es caused by sterility in couples. However, it poses some problems who
se solutions involve three main directions in research. Fundamental re
search explores spontaneously occuring phenomena. It shows that over a
nd above common general points of sexual reproduction, mechanisms can
differ from one to another. Technical research perfects artificial emp
irical methods which lead to fertilization, implantation and pregnancy
. It shows that success varies from one species to another. Concerning
some technologies such as intracytoplasmic sperm injection, successfu
l results began with humans where they seem to be easier to obtain. Re
search of risks cheks, in animals, the absence of adverse effects of t
he above techniques for conceptus. It has confirmed the harmfulness of
some environmental factors for gametes and zygotes. Moreover, it show
s that these negative effects vary between species and within them for
strains and sex. For instance, the cryopreservation of mouse embryos
leads to changes in the offspring concerning morphophysiological and b
ehavioral features, some of them appearing in elderly subjects. Indeed
, these changes vary as a function of strain and sex. These results as
a whole show that experimentation on animals can indicate research ar
eas and also give rise to the need for caution. However, if we want to
act on human reproduction, they also show, because of the variations
in reactivity from one species to another, that the animal model is in
sufficient and that research in man is essential. From this point of v
iew, a long term follow up of AHR children seems necessary, as well as
the need for reflexion concerning the possibility and conditions of r
esearch on human embryos.