Fig. 1

Teratogenic lesions associated with intrauterine infection with bovine virus diarrhea virus (BVDV) in cattle. The lesions are representative also for other teratogenic viruses infecting cattle. a Severe cerebellar hypoplasia. There are only small irregular parts of the developing cerebellum (black asterisk). Posterior to the cerebellar tissue, the 4th ventricle is visible which is covered by congested choroid plexus tissue (white asterisk). b Hydranencephaly. The posterior and dorsal parts of the cerebral hemispheres are collapsed, partially ruptured and covered by thin membranes consisting of congested leptomeningeal tissue. The cerebellum is severely hypoplastic and reduced to a small, narrow mass of tissue (arrows). Between the posterior parts of the collapsed cerebral hemispheres and the hypoplastic cerebellum the rostral and caudal colliculi (asterisks) of the quadrigeminal plate are visible. c Hydranencephaly. There is marked bilateral thinning of the grey and white matters of the cerebral brain tissue surrounding the extremely dilated lateral ventricles. The dorsal parts of the cerebral hemispheres are partially covered by thin, partly translucent leptomeninges. Beneath the meninges the brain tissue is focally absent (arrow). Transverse brain section at the level of the optic chiasm. d Bilateral internal hydrocephalus. There is slight dilation of both lateral ventricles (asterisks). In the cerebral white matter bilateral porencephalic cysts are present (arrows). e Doming of the calvarium due to hydrocephalus. f Porencephalic cysts in the cerebellum. Cut surfaces of cerebellar tissue reveal the presence of variable-sized cystic cavities affecting the cerebellar hemispheres and the vermis (arrows). a–e Spontaneous foetal infection with BVDV, f Experimental foetal BVDV infection