Phenotype of congenital osteopetrosis in affected Red Angus calves. A. Head of a late-term stillborn calf with inferior brachygnathia, short flattened skull and protruding tongue. B. Impacted unerupted molar (M) and incisor teeth (I) in mandibles of an affected calf. C. Posterior aspect of skull with partial herniation of cerebellum through foramen magnum (arrow). D. Distal aspect of a sagittally sectioned femur with a triangle of primary spongiosa (PS) resting on the distal growth plate and extending into the diaphysis. The normal marrow cavity is effaced. E. Marked compression of cerebral hemispheres (asterisk) due to excessive thickness of calvarium. The lesions shown in C and E (cerebellar herniation and compression of cerebral hemispheres), combined with mineralization within the brain, are likely responsible for death of calves in utero with stillbirth.