Ocular toxoplasmosis is present in 20% of infected immunocompetent individuals. 
Toxoplasmosis is the most common cause of posterior uveitis in immunocompetent 
subjects and congenital toxoplasmosis transmission was the first parasite to be 
linked to human lesions in the eye. An experimental model for congenital ocular 
toxoplasmosis was developed in C57BL/6 mice with the purpose to evaluate 
Toxoplasma induced ocular pathology during fetal life. Toxoplasma gondii, ME-49 
strain, was used to infect pregnant females. Histological analysis of pre-natal 
fetal eyes from infected female mice, did not show parasite infestation, 
however, alterations were observed in the outer nuclear layer (ONL) and in the 
inner nuclear layers (INL) of the retina. Edema was also observed, characterized 
by the increase of interstitial spaces forming lacunae between the ONL and INL 
cells and a net of vessels associated with an intense inflammatory infiltrate. 
These histological observations suggest that ocular lesions are not delayed 
manifestations of toxoplasmosis. The eye was affected in the initial phase of 
disease, and these alterations were of similar nature as those observed in mice 
at later stages of infection.