Rat and cat spinal cords were exposed to 2000, 3000 or 4000 rads of x-irradiation prior to producing an area of primary demyelination in the dorsal columns by the injection of lysolecithin. In animals irradiated with 4000 rads no remyelination by either Schwann cells or oligodendrocytes occurred. With 2000 rads both types of remyelination occurred, but when… (More)
Internodes from normal, remyelinated and regenerated nerve fibres have been isolated from rat spinal roots and sciatic nerve. The internodes have been examined quantitatively by light and electron microscopy to determine their internodal length, myelin thickness, and the circumference and cross-sectional area of both the axons and fibre. Comparison of these… (More)
Let be an array of rowwise conditionally negative dependent random variables. Complete convergence of to 0 is obtained by using various conditions on the moments and conditional means.
Myelination was inhibited in the spinal cord of three day-old rats with 2000 rads of X-irradiation. Myelination subsequently occurred as a result of caudal migration of oligodendrocytes and extensive invasion of the cord by Schwann cells. Although oligodendrocytes were present in areas containing Schwann cells, astrocytes were absent. The presence of… (More)
We explored the feasibility of using lexical analysis software to help identify biological concepts in students' open-ended responses. We created two items in an on-line course management system where we asked students to trace carbon during cellular respiration. Data were collected during the fall semesters of 2004 and 2006. We created a custom library of… (More)
Injection of a suspension of embryonic rat central nervous system (CNS) cells into an area of persistent demyelination, produced in the cat spinal cord by injecting ethidium bromide into an area previously exposed to 40 Grays of x-irradiation, results, initially, in Schwann cell remyelination of the demyelinated axons. However, the Schwann cells are… (More)
The injection of suspensions of central nervous system (CNS) cells, prepared by standard methods from 4-day-old rat brain and maintained in vitro for 10 days, into areas of persistent demyelination in rat spinal cord resulted in extensive remyelination of axons by Schwann cells. As control lesions injected with medium showed no remyelination, the most… (More)
Morphometric analysis was carried out on electron micrographs of motor endplates from three Jack Russell terriers affected with congenital myasthenia gravis (CMG) aged 10 weeks, 12 weeks and 22 weeks, respectively. Control endplates from age-matched pups and an adult Jack Russell were also examined. The results showed that postsynaptic membrane density was… (More)