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T F Fletcher

Publications and source records attributed to T F Fletcher.

At least 37 records · Page 2Linked to original sources
PubMed1983

Morphometry of the female feline urethra.

Tissues composing the lower urinary tract of the female cat were discribed and analyzed morphometrically. Statistical comparisons were made with the female dog using previously obtained canine morphometric data. Despite a superficial similarity, the cat differs from the dog in having a significant component of longitudinally oriented urethral smooth muscle and appreciably less striated urethral sphincter. It is suggested that the cat requires an active mechanism for overcoming continence due to an inherently smaller urethral lumen, compared to the dog. The implication of our morphometric findings is that urethral mechanics are different for the female cat and dog.

Animals↗
PubMed1981

Studies of a synthetic substrate in canine globoid cell leukodystrophy.

Gal et al. ((1977) Clin. Chim. Acta 77, 53-59) reported the use of a new synthetic substrate, 2-hexadecanoylamino-4-nitrophenyl-beta-D-galactopyranoside for the diagnosis of human globoid cell leukodystrophy. Assay of beta-galactosidase in brain homogenates from normal, carrier, and globoid cell leukodystrophy-affected dogs utilizing this new substrate demonstrated overlapping activities. Instead of reflecting specific D-galactosyl-N-acylsphingosine galactohydrolase (EC 3.2.1.46), the 2-hexadecanoylamino-4-nitrophenyl-beta-D-galactopyranoside beta-galactosidase activity in canine brain is highly correlated with nonspecific 4-methylumbelliferyl beta-galactosidase. Optimization of the 2-hexadecanoyl-amino-4-nitrophenyl-beta-D-galactopyranoside assay system for canine brain and the use of varying concentrations of taurocholate or taurodeoxycholate in the assay mixture did not alter the lack of specificity. These results indicate a significant difference in the nature of the underlying defect in galactosylceramide beta-galactosidase in canine globoid cell leukodystrophy compared to human globoid cell leukodystrophy.

Animals↗
PubMed1981

Histology of the canine urethra. I. Morphometry of the female urethra.

Urinary bladders and urethrae were collected from six adult and two juvenile female dogs. Five urethral regions and the neck and body of the bladder were sampled. Volume fractions for connective tissue including elastic fibers, smooth and striated muscle, and epithelium were obtained by projecting section images onto an array of points and computing the number of points overlying a tissue constituent per total points overlying the tissue section. Smooth muscle occupied approximately half the volume of the bladder wall, one-third the volume of the vesical neck, and one-fourth the volume of the proximal urethra. Striated muscle was present in the distal half of the urethra, where the total muscle coat occupied about one-third of the urethral wall volume. Smooth muscle was practically absent in the terminal urethra, where the striated urethralis muscle encircles urethra and vagina in common. Epithelial area and lumen perimeter were not significantly different along the length of the urethra except that urethral epithelium was significantly thicker adjacent to the vesical neck. In terms of histological proportions, the vesical neck was intermediate between the body of the bladder and the proximal urethra.

Aging↗
PubMed1981

Histology of the canine urethra II. Morphometry of the male pelvic urethra.

Urinary bladders and pelvic urethrae were collected from six adult and two juvenile male dogs. Within two vesical and six urethral sampling regions, volume densities were estimated for smooth and striated muscle, connective tissue and elastic fibers, stratum cavernosum, luminal epithelium, and prostate. The neck had significantly less smooth muscle and more connective tissue than the body of the bladder. In the prostatic urethra, smooth muscle was associated principally with trabeculae surrounding prostate lobules. Smooth muscle was sparse superficially in the prostatic capsule and practically absent in relation to the mid-prostatic urethra. Thus there was no mechanism for active closure of the middle prostatic urethra, and elastic fiber density was correspondingly high in this region. The smooth muscle sphincter needed to maintain urinary continuence and prevent semen reflux was primarily the vesical neck. Caudal to the body of the prostate, striated muscle comprised more than 40% of the urethral wall. Juvenile and adult postprostatic urethrae were similar except for a decreased quantity of stratum cavernosum in the pups.

Aging↗
PubMed1981

Quantification of microvasculature in the canine spinal cord.

Capillary density and capillary orientation in canine spinal cords were estimated by calculating actual lengths, surfaces, and volumes of capillary segments in tissue sections. Transverse, sagittal, and frontal section planes were samples from dorsal, ventral, and lateral funiculi and from dorsal and ventral gray horns of spinal segments C3, T6, and L3 from three dogs. Capillaries were defined as vessels less than 10 micrometer in diameter. Electron microscopy of 104 such vessels revealed no muscle coat but collagen fibrils between endothelium and astrocyte process in 68% of the white matter capillaries and 16% of those in gray matter. Capillary diameter was significantly different among regions in some cases, but consistent patterns of variation were not found. Capillary density was four to five times greater in gray matter than in white matter. Capillary density differed significantly among the same-size dogs, but within dogs, density was similar among segments and within gray matter and white matter regions. In 62% of the transverse sections, capillary orientation was always along the craniocaudal axis of the spinal cord. The craniocaudal orientation was significant in 96% of the white matter sections and 78% of the gray sections, and in 97% of the cervical and thoracic sections but only 73% of the lumbar sagittal and frontal sections. Because capillary orientation is neither isotropic nor regular, unbiased, low-variance estimates of capillary density cannot be expected without resorting to excessive sampling. An efficient method of quantifying spinal capillaries for comparative purposes by counting number of profiles per unit area is recommended.

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PubMed1978

Cilia of neonatal articular chondrocytes: incidence and morphology.

Cilia in neonatal canine articular chondrocytes were studied using morphometric techniques and transmission electron microscopy. The cilia in chondrocytes were morphologically similar to cilia in a variety of other cell types. A chondrocytic cilium consisted of a basal body and a ciliary shaft. The cylindrical basal body was 0.21 micron (S.D. = 0.01 micron) in diameter, 0.50 micron (S.D. = 0.03 micron) in length and contained nine microtubular triplets. The ciliary shaft was 0.196 micron (S.D. = 0.02 micron) in diameter and 1.76 micron (S.D. = 0.80 micron) in length. The number of microbtubular doublets in the ciliary shaft varied depending on where along the length of the shaft the section was taken. This study demonstrates that on the average the frequency of cilia in neonatal articular chondrocytes, as estimated sterologically, was about one cilium per cell.

Animals↗
PubMed1977

Sub-plasmalemmal linear density: a common structure in globoid cells and mesenchymal cells.

Sub-plasmalemmal linear densities of variable length (0.1 approximately 1.0 mu) were found to be a constant feature of globoid cells in human as well as in canine globoid cell leukodystrophy (GLD). Similar densities were also observed in experimental globoid cells and epithelioid cells in chronic granuloma but not in glial cells. The linear densities always appeared without any relation to basal laminae. These observations together with the other reports of similar structures in lymphoma, fibroma and sarcoidosis suggest that the sub-plasmalemmal density is a structure frequently observed in mesenchymal cells, and may be another supporting feature for possible mesenchymal origin of globoid cells.

Animals↗
PubMed1977

Canine globoid cell leukodystrophy. Part 1. Further ultrastructural study of the typical lesion.

The ultrastructural changes of typical lesions in canine globoid cell leukodystrophy (GLD) have been studied. The globoid cells were located in the cerebral parenchyma as well as in the perivascular Virchow--Robin space. Features suggestive of a passage of the globoid cells from the cerebral parenchyma to the Virchow--Robin space were also observed through the interruptions in the basal lamina. The globoid cells had numerous thin pseudopods and contained various cytoplasmic inclusions which have been described previously. Detailed studies of these inclusions suggest that they represented aggregates of filamentous or linear sub-unit structures. Typical oligodendroglial cells were found on only a few occasions. Both globoid cells and oligodendroglia contained myelin debris, dense bodies and honey-comb like inclusions composed of numerous small myelin figures. In a few instances, crystalline polygonal inclusions identical to those found in the globoid cells, were found in the cytoplasm of the cells which were, with reasonable certainty, identifiable as oligodendroglia. In less affected areas where myelin was still present, degenerating oligodendroglia, with or without recognizable inclusions, were frequently encountered. Astrocytes and endothelial cells contained concentric lamellar inclusions and dense bodies but did not contain the tubular inclusions as seen in globoid cells. The possible significance of the ultrastructural features in regard to the pathogenesis of the GLD have been discussed.

Animals↗
PubMed1977

Quantitative evaluation of spinal cord lesions in canine globoid leukodystrophy.

Lesion distribution in the spinal cord was investigated by sampling an average of 26 spinal cord segments in each of ten dogs severely affected by canine globoid leukodystrophy (GLD). GLD lesions were quantified by subdividing spinal white matter into small unit areas and judging the quartile extent of lesion involvement for each unit area. Along the length of the spinal cord, lesions declined from cranial to caudal, decreasing precipitously in the midlumbar region. The lumbosacral region had the least amount of lesion, and, based on lesion per unit area, the thoracic region was most severely involved. The dorsal funiculus had the greatest concentration and the least dispersion of lesion generally amoung the three funiculi. White matter at the periphery of the spinal cord was involved earlier and more severely than white matter adjacent to gray matter. Amount of lesion per spinal cord could be estimated adequately by sampling one segment from each of five regions. Dogs could be divided into two groups based on rate of lesion development. Clinical signs did not correlate closely with total amount of lesion per spinal cord. Of the total amount of variability among dogs in amount of spinal pathologic involvement, 78% could be accounted for by a mathematical model expressing spinal cord pathologic involvement as a quadratic function of age at onset and duration of the clinical syndrome.

Age Factors↗
PubMed1977

Galactocerebrosidase activity in canine globoid leukodystrophy.

In an investigation of canine globoid leukodystrophy, cerebroside beta-galactosidase activities were assayed in 24 brains from neonatal and older dogs and in 90 canine leukocyte pellets from nine samplings. The neonatal brains had significantly less enzyme activity than the brains of older dogs, which indicates a potential complication in making neonatal and fetal enzymatic diagnoses. For leukocytes, heterozygous activities averaged 51 percent and globoid leukodystrophy activities 18 percent of mean enzyme activity of normal leukocytes. Variability of leukocyte enzyme activities among the nine samplings was large, but within each sample, variability per genotypic category was moderate. A statistical model was developed to facilitate enzyme diagnosis in the dog and, by implication, in human globoid leukodystrophy and other sphingolipidoses.

Animals↗
PubMed1976

Innervation of pelvic viscera in the rat. Evoked potentials in nerves to bladder and penis (clitoris).

In 29 rats, responses evoked by pelvic and hypogastric nerve stimulation were recorded from postganglionic nerves to bladder and penis (clitoris). Responses to pelvic nerve stimulation had nonsynapsing and synapsing components. The nonsynapsing component was relatively large in main nerve to penis and small in lateral nerve to penis and nerves to bladder. Pelvic nerve fiber synapsing on pelvic ganglion neurons to bladder had a large subliminal fringe, while fibers synapsing on neurons supplying penis (clitoris) had a small subliminal fringe. Recruitment was greater in nerves to bladder and lateral nerve to penis (clitoris) compared to main nerve to penis (clitoris), indicating more synapsing fibers in the former nerves. Almost all hypogastric fibers to bladder were direct. A small subliminal fringe was demonstrated for hypogastric fibers synapsing on neurons supplying penis. No subliminal fringe was evident for the bladder. Pelvic and hypogastric nerve interaction on pelvic ganglion neurons could not be demonstrated with either single shock or tetanic trains of conditioning stimuli. With antidromic stimulation, conduction velocities of afferent fibers in pelvic nerve ranged from 0.15 m per sec to 2.9 m per sec. In hypogastric nerve they ranged from 0.35 m per sec to 2.8 m per sec.

Animals↗
PubMed1975

Distribution of lumbar and sacral afferent axons in submucosa of cat urinary bladder.

Lumbar and sacral afferent axons in the submucosa of the urinary bladder were recognized by degeneration in seven cats subjected to spinal ganglionectomies. Of 2,935 observed terminating axon profiles, 145 were found degenerating. Lumber afferent axons were 3.7 times more numerous than sacral afferent axons in the submucosa, a reversal of the ratio reported for the muscle coat of the bladder. Sacral afferent axons were evenly distributed to different regions of the bladder, but lumbar afferents were concentrated in the bladder neck. Apparent afferent endings in the submucosa of the urinary bladder were principally free nerve endings. Synaptic vesicles were found in 57% of observed terminating axon profiles. The bladder neck had more terminating axon profiles of all kinds than other regions of the urinary bladder.

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