The Campanian of Alberta and Saskatchewan produce the oldest hiodontid fossils from North America, which are represented only by isolated centra. As such, very little is known about the taxonomic affinities, morphology, life history characteristics, and paleoecology of the taxon or taxa represented by the Cretaceous centra. To study the age and growth characteristics of Hiodontidae from the Cre...

Lake Metztitlán was dried up completely in the spring of 1998 and refilled in August of that year. In the period September-November, two cohorts of 1.6 million juveniles of a tilapia hybrid were stocked (Oreochromis aureus/O. niloticus), and monitored every month for one year. Since the date of birth of these juveniles was known, the analyses focused on whether the ring marks of the scales, sag...

Lissencephaly is a rare malformation of the human brain manifest by a smooth cerebral surface. It is usually associated with other brain anomalies. The computed tomographic appearance in nine patients with lissencephaly, representing several separate types and syndromes, is reported. Common manifestations include a smooth cerebral surface and absent opercula that may lend a figure-eight appeara...

PURPOSE To evaluate abnormalities of the cerebral operculum in infants and children and to propose the embryogenic basis of abnormal opercular formation as determined from MR imaging findings. METHODS Eighty-six infants and children who had abnormally wide interopercular distances and/or distorted opercular topography seen on MR images were studied retrospectively. Clinically, patients presen...

Human ability to imitate movements is instantiated in parietal, premotor and opercular structures, often referred to as the human homologue of the macaque mirror neuron system. As most studies employed imitation of specular models (participants imitated the seen movement as their mirror reflection), it is unclear whether the structures implicated code for the anatomical compatibility between th...

Within monocotyledons, monosulcate pollen is the predominant type and probably represents the plesiomorphic condition, but considerable variation occurs in sulcus morphology. An operculum is an exine thickening that covers most of an aperture. Monocot opercula are usually associated with sulci, although they can occur in ulcerate apertures, as in Poaceae. There are several other aperture types ...

PURPOSE To identify a pattern of findings on CT or MR of the brain in glutaric acidemia type I typical enough to permit a correct diagnosis. METHODS Clinical history and findings and brain CT and MR results in 59 previously reported patients (MR in 12) and in 5 new patients (all examined with MR and 3 also with CT) were reviewed. RESULTS In half the patients macrocephaly was present, and in...