Midpoint Width Research Articles

Can a fixed measure serve as a pertinent diagnostic criterion for large vestibular aqueduct in children?

A vestibular aqueduct midpoint width greater than 1.50 mm is currently considered to be pathognomonic for a large vestibular aqueduct syndrome. To analyse the diameter of the vestibular aqueduct in children as a function of age and consequently to determine if a fixed measure could serve as a pertinent diagnostic criterion. This was a retrospective study of 200 high-resolution CT scans of the ear in 100 patients aged 0-16 years and from various paediatric medical departments. On each CT scan, the lateral semicircular canal diameter, the vestibular aqueduct midpoint width between the external aperture and common crus, and the vestibular aqueduct external aperture diameter were measured. Spearman's rank test and the Mann-Whitney correlation test were used for an integrated statistical analysis. There was no statistically significant variability in vestibular aqueduct diameter as a function of age or sex of patients. A CT scan threshold value, fixed and independent of age and sex, is thus legitimate for the diagnosis of vestibular aqueduct dilatation.

THE MENISCOFEMORAL LIGAMENTS OF THE KNEE

The meniscofemoral ligaments (MFL) of the knee have both functional and clinical importance, but have been poorly described. We examined 42 human cadaver knees: there was at least one MFL in every joint and both ligaments were present in 27. The anterior MFL was present in the knees in all 18 males and in 17 of the 24 females. The posterior MFL was present in 16 males and 22 females. Measurement of the ligaments showed that they were of significant size. The mean midpoint width for the anterior MFL was 5.09 ± 1.41 mm in males and 2.99 ± 1.29 mm in females. The mean width of the posterior MFL was 5.48 ± 2.13 mm in males and 3.79 ± 2.56 mm in females. The average length of the anterior MFL was 27.09 ± 2.15 mm in males and 24.38 ± 3.39 mm in females, and the posterior MFL was 31.13 ± 2.54 mm and 27.59 ± 3.74 mm, respectively. There were anatomical variations in 16 (38%) knees (62.5% female, 37.5% male), more commonly in the posterior ligament. We conclude that the meniscofemoral ligaments are anatomically and probably functionally important structures in the human knee.

The meniscofemoral ligaments of the knee.

The meniscofemoral ligaments (MFL) of the knee have both functional and clinical importance, but have been poorly described. We examined 42 human cadaver knees: there was at least one MFL in every joint and both ligaments were present in 27. The anterior MFL was present in the knees in all 18 males and in 17 of the 24 females. The posterior MFL was present in 16 males and 22 females. Measurement of the ligaments showed that they were of significant size. The mean midpoint width for the anterior MFL was 5.09 +/- 1.41 mm in males and 2.99 +/- 1.29 mm in females. The mean width of the posterior MFL was 5.48 +/- 2.13 mm in males and 3.79 +/- 2.56 mm in females. The average length of the anterior MFL was 27.09 +/- 2.15 mm in males and 24.38 +/- 3.39 mm in females, and the posterior MFL was 31.13 +/- 2.54 mm and 27.59 +/- 3.74 mm, respectively. There were anatomical variations in 16 (38%) knees (62.5% female, 37.5% male), more commonly in the posterior ligament. We conclude that the meniscofemoral ligaments are anatomically and probably functionally important structures in the human knee.

A Scanning Electron Microscopic Study of Third-Stage Larvae of Dirofilaria immitis

Recent use of SEM techniques has revealed the fine surface architecture of various developmental stages of Dirofilaria immitis. Sonada and Kobayashi (1965, Jap. J. Vet. Res. 13: 6771) and Aoki and Katamine (1975, Trop. Med. Nettai Igaku 17: 27-34) examined the microfilarial stage using SEM techniques. Tulloch et al. (1972. In Canine heartworm disease: The current knowledge, R. E. Bradley (ed.). University Presses of Florida, Gainesville, Florida, pp. 113115) described the en face view of the adult male D. immitis, while Wong and Brummer (1978, J. Parasit. 64: 108-114) compared the morphology of five species of adult Dirofilaria, including D. immitis. There have been no SEM studies of the third larval stage of D. immitis. The purpose of our study was to examine surface architecture of the third larval stage of D. immitis obtained from mosquitos using SEM techniques. A laboratory strain of Anopheles quadrimaculatus was fed on a dog whose blood contained 16 D. immitis microfilariae per 0.1 ml of blood. The mosquitoes were housed for 26 days in an environmental chamber with an air temperature of 26 C and RH of approximately 80%. Incandescent lighting was used to simulate 8 hr of daylight each 24-hr period. On the 26th day after feeding, the mosquitoes were dissected in Hanks' balanced salt solution. The third-stage larvae released from the mosquito were pipetted into a solution of 4% glutaraldehyde in 0.1 M phosphate buffer (pH 7.2). The larvae were rinsed several times in 0.1 M phosphate buffer and then postfixed in 1% osmium tetroxide in 0.1 M phosphate buffer. Following five rinses in distilled water, the larvae were dehydrated in an ascending series of ethyl alcohol washes (50-100%). Larvae were then critical point dried in absolute ethyl alcohol. Individual larvae were positioned on a 13-mm diameter silver filter (pore size 5.0 ,um). The silver filter was then mounted on an aluminum stub using Acme? conductive silver paint; the silver paint perfused through the filter to stabilize the individual larvae. The larvae were coated with gold-palladium in a Denton? Vacuum Evaporator system and were examined with a JEOL (JSM-35) SEM at an accelerating voltage of 25 kV. The length of third-stage larvae was determined by first photographing the larvae at x 100 with the SEM. A caliper was set to the standard unit (the width of a grid bar and space, 129 Atm) and Iyengar's (1957, So. Pac. Com., Tech. Paper No. 104, pp. 1-11) method of measurement was then used to count the steps of the caliper legs along the median line of only larvae which lay flat on the silver filter. The midpoints of these larvae were then determined. The midpoints of the larvae were photographed at x 1,000. At this magnification, one centimeter equaled ten ,um. The midpoint widths of the larvae were then measured on the photographs. Thirteen third-stage larvae were suitable for measurement. These larvae had a mean length of 886 Aim (range 774-988 ,um) and a midpoint width of 15.2 Atm (range 13-18 ,tm). At x100 magnification, the anterior end of the larva was shown to be tapered, while the posterior end was blunt (Fig. 1). The cuticle of the third-stage larva had numerous transverse striations (Figs. 2-4), with the exception of the terminal 2.5 ,um of the anterior end. Four small inner papillae, four large outer papillae, and two small papillae located between the circle of inner papillae and the circle of outer papillae encircled the mouth. We describe this configuration as a 4-2-4 papillary configuration (Fig. 2). In all of the specimens examined, the number of outer papillae was constant. However, there were variations in the total number of inner and mid-position papillae surrounding the mouth, ranging from three to six papillae. The posterior end of the third-stage lar-