Bovine meroanencephaly and gastroschisis: a macro and microscopic study.

Congenital malformations correspond to one of the main causes of embryonic loss during the gestational process. They result from interaction of several factors such as multifactor heredity, chromosomal and genetic alterations and environmental agents; however, unknown aetiology also can be present. In this article, we have used 10 embryos, from a frigorific area of Dracena, SP, Brazil, which were fixed in Bouin solution for a macro- and micro-scopic description. We could verify the presence of an encephalic tissue mass on the embryo's dorsal cranial area, resulting from the non-formation of part of the cranial cap and from the non-closing of cephalic neuropore and consequent neuroepithelial cells disorganization. In the abdominal area, the embryos did not show the complete fusion of the body lateral pleats during the abdominal wall formation, and the liver extruded into the amniotic cavity without involvement of the intestine.

Ependymoblastomatous exencephaly: a unique fetal malformation.

Exencephaly/anencephaly is a rare neural tube defect occurring early in embryogenesis. We report a 14-week-old fetus with exencephaly in whom central nervous system tissue was developed and preserved. There were 2 symmetrical structures grossly resembling cerebral hemispheres, which on histologic and ultrastructural study, consisted of a combination of ependymoblastomatous rosettes and canals and primitive neural tissue. The brainstem and spinal cord were partially normally formed, although descending tracts were not apparent. No cerebellar tissue was found. The eyes were formed. This appears to represent a rare example of exencephaly not covered by skin, which did not undergo necrosis and early transformation into a residual area cerebrovasculosa, characteristic of anencephaly. It may be appropriate to regard this as a unique neural tube closure defect that might be termed "ependymoblastomatous exencephaly."

The eyes of anencephalic babies: a morphological and immunohistochemical evaluation.

This study studied the eyes of three anencephalic stillborns to evaluate whether brain degeneration affected eye development and/or survival. The study encompassed histology, scanning electronmicroscopy, and immunocytochemistry. The corneae were otherwise normal except for the presence of blood vessels in the stroma and the posterior surface of the cornea demonstrated wrinkles. Synaechia was present and the lens had occasional vacuolated cells. The retinae had normal layers in most regions except the center where fibroblasts infiltration was observed. The optic nerve was atypical and composed of aggregates of disoriented fibroblasts and disoriented nerve fibers. Anti-cleaved caspase 3 immunocytochemistry revealed only few positive dying cells in the visual cell layer. Antineurofilament 200 reactions demonstrated positive ganglion cells even in the anencephalic eyes. The choroids in anencephaly had more VEGF positive sites, indicating vascularization in both control and anencephalic eyes. If the brains degenerate before retinal maturation, then such degenerations may not have an effect on subsequent retinal development except for the degeneration of the nerve fiber layer. If the brains degenerate after retinal maturation, then the survival of the retinae does not appear to rely on its linkage with the brain at birth, again apart from the degeneration of nerve fibers.