The purpose of this study was to investigate magnetic resonance imaging (MRI) of the normal feline eyeand optic nerves using T1-weighted and T2-weighted images. A total of 6 healthy female domestic short haircats age 2-2.5 years and weighing 3.2 ± 0.4 kg were selected. Magnetic resonance imaging data werecollected using GEMSOW (Philips) at a magnetic field strength of 1.5 T. Dorsal, sagittal, a...

Trisomy is the most common genetic abnormality in humans and is the leading cause of mental retardation. Although molecular studies that use a large number of highly polymorphic markers have been undertaken to understand the recombination patterns for chromosome abnormalities, there is a lack of multilocus approaches to incorporating crossover interference in the analysis of human trisomy data....

The brains from 14 adult common tree shrews (Tupaia glis) of both sexes were used for the study of hypothalamic blood supply. It is found that the hypothalamus is supplied by branches of arteries that form the circle of Willis. The preoptic region of the anterior hypothalamus is supplied by branches of anterior cerebral and anterior communicating arteries, while branches of the ophthalmic, ante...

The relationship between meiotic recombination events and different patterns of pairing and synapsis has been analysed in prophase I spermatocytes of the grasshopper Stethophyma grossum, which exhibit very unusual meiotic characteristics, namely (1) the three shortest bivalents achieve full synapsis and do not show chiasma localisation; (2) the remaining eight bivalents show restricted synapsis...

The effects of chromosomal rearrangements on recombination rates were tested by the analysis of chiasma distribution patterns in wild house mice. Males and females of two chromosomal races from Tunisia differing by nine pairs of Robertsonian (Rb) fusions (standard all-acrocentric, 2N = 40 and 2N = 22) were studied. A significant decrease in chiasma number (CN) was observed in Rb mice compared t...

Embryonic discs from White Leghorn chick embryos (presomite to 12-omite stages) were examined in serial transverse and longitudinal sections. Later stages, up to 21 days, were also examined. The following observations were made: (1) Lateral folding rather than head folding is the mechanism by which the avian embryo is delimited. The process takes place at two terminal points, one cephalic the o...