No abstract

In the golden hamster, there are marked sex differences in the Harderian gland. Male glands (which are heavier than female glands) possess two cell forms (Type I and Type II cells); female glands only exhibit the former. Female (but not male) glands contain large amounts of porphyrin, which are readily visible as solid depositions within the lumina. The weight, histology and porphyrin content of the Harderian gland was examined in intact adult male hamsters and in male hamsters castrated for 1,2 or 8 months. Castration resulted in a significant reduction in the weight of the gland, the disappearance of Type II cells, and the presence in the gland of solid porphyrin accretions. The levels of copro- and (especially) protoporphyrin were greatly increased. These changes were more marked with time after castration. When the ability of diverse androgens (testosterone, 5alpha-dihydrotestosterone, androst-4-ene-3,17-dione (androstenedione), dehydroepiandrosterone and androsterone) to prevent these changes was tested, testosterone and androstenedione maintained glandular weight. All the androgens maintained normal frequencies of Type II cells and all except dehydroepiandrosterone prevented deposition of porphyrin. The potencies of the various androgens in maintaining normal Harderian gland morphology and activity are compared with their effects on other somatic variables and sexual behaviour.

The aim of this study was to evaluate the effects of Nd:YAG laser treatment on subgingival calculus, cementum and dentine, in vitro at different power settings and durations. The study included 2 experiments. In the 1st experiment, 32 extracted teeth with calculus were divided into 8 laser treatment groups. Each tooth was treated on 2, 3 or 4 sites. In the 2nd experiment. 3 extracted cementum covered teeth and 3 extracted root planed teeth with exposed dentine were selected. 1 surface of each tooth was subjected to 8 different laser treatments. In both experiments, all specimens were assessed using scanning electron microscopy. Micrographs were taken from each treated site at X100 and X750 magnifications. An arbitrary scale (from 0 to 3) was used to score the degree of damage caused by the laser. Generally, the laser caused greater damage on calculus than either cementum or dentine. Linear regression analysis showed that higher total energy input caused a greater mean damage score on calculus (R2= 66%, p<0.001). 3‐way analysis of variance showed that for calculus, the power setting, number of pulses per second and the duration of exposure contributed independently to the mean damage score in an additive way. Cementum specimens were not affected by treatment 1 (50 mJ. 10 pps, 1 s). treatment 2 (50 mJ, 10 pps, 5 s), and treatment 5 (50 mJ, 20 pps, 1 s). Dentine specimens were not affected by treatment 1 (50 mJ, 10 pps, 1 s). The results also showed that there was variability in susceptibility of different teeth and different parts of each tooth which was true for calculus, cementum and dentine.

We have examined, by scanning and transmission electron microscopy, morphological changes in the choroid plexus of the lateral ventricles of the non-human primate brain after lateral head acceleration. We demonstrate passage of plasma and blood cells either through tears in blood vessels and the choroidal epithelium, or through the cells of the choroidal epithelium, 20 min after injury, together with morphological changes in that epithelium. At 3 and 4 h small cells with a reniform nucleus accumulate in the connective tissue core of the choroid plexus. We suggest that these are monocytes. At 6 and 12 h cells can be seen in enlarged intercellular spaces within the choroidal epithelium. These cells possess surface ruffles and we suggest that they are monocytes differentiating into macrophages and epiplexus cells. Further evidence for transepithelial migration of monocytes/macrophages is obtained at 7 days. However, at 28 days all blood has been removed from the surface of the choroid plexus and epiplexus cells possess an appearance typical of that in uninjured animals. The possible sources of epiplexus cells are discussed with reference to studies of responses after brain insult and of development. We have obtained no evidence in support of emperipolesis by monocytes through the choroidal epithelium. We suggest that monocytes/macrophages migrate, via an intercellular route, to differentiate into epiplexus cells, thus providing additional numbers of epiplexus cells after head injury.

A Neodymium-yttrium aluminium garnet (Nd-YAG) pulsed laser was used in vitro to determine whether various laser energy levels from 0.75 W to 1.7 W at 15 pulses s(-1) (pps) were able to (i) remove debris from the walls of prepared root canals (ii) remove pulpal tissue from unprepared canals and (iii) create a fused apical plug from dentine chips, hydroxyapatite (HAP) or low-fusing dental porcelain. Single-rooted teeth were sectioned at the amelocemental junction and the crowns discarded. The root canals of 50 teeth were prepared chemomechanically and allocated to four groups of 10 teeth for laser treatment. One group was left unlased as a control. After lasing, the teeth were split longitudinally, stained and examined for residual debris. Results showed that there was no statistically significant difference between the groups (P<0.05). A further 20 teeth were not prepared and lased in the coronal one-third of the root canal at different energy levels; five teeth were not lased. The teeth were split and examined as previously. The results showed that lasing cleaned the coronal part of the root canal almost completely of pulpal tissue. In the final part of the study laser energy was applied to dentine chips, HAP and low-fusing porcelain in an attempt to produce a fused apical plug. The laser was unable to melt the dentine chips but some hardening of HAP occurred when combined with blue food-colouring, with or without glycerine, at energy levels of 1.0 W, at 15 pps for 30 s. Superficial hardening of low-fusing porcelain occurred at 1.0 W, 15 pps for 30 s.