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Tonsilloliths, also known as tonsil stones or tonsillar calculi are clusters of calcified material that form in crypts of palatine tonsil. They are usually of small size. Large or giant tonsilloliths are rare. We report a case of giant tonsillolith in left palatine tonsil and literature is reviewed. Keywords: Tonsillolith, Tonsil stone.

We compared the covering behavior of four sea urchin species, Tripneustes gratilla, Pseudoboletia maculata, Toxopneutes pileolus, and Salmacis sphaeroides found in the waters of Malapascua Island, Cebu Province and Bolinao, Panagsinan Province, Philippines. Specifically, we measured the amount and type of covering material on each urchin, and, in several cases, the recovery of debris cover after stripping the animal of its cover.We found that Tripneustes gratilla and Salmacis sphaeroides have a higher preference for plant material, especially sea-grass, compared to Pseudoboletia maculata and Toxopneutes pileolus, which prefer to cover themselves with coral rubble and other calcified material. Only for Toxopneutes pileolus did we find a decrease in cover with depth, confirming previous work that the covering behavior serves UV protection. We found no dependence of particle size on either species or urchin size, but we observed that larger urchins carried more and heavier debris. We observed a transport mechanism of debris onto the echinoid body surface utilizing a combination of tube feet and spines. The transport speed of individual debris items varied between species.We compare our results to previous studies of urchin covering behavior, comment on the phylogeny of urchin covering behavior and discuss the interpretation of this behavior as animal tool use.

Background Three Nordic countries have national breeding programs to reduce the frequency of intervertebral disc disease in dachshunds. The programs include a radiographic examination of the vertebral column and dachshunds with more than four calcified discs visible on radiographs (CDVR) are discouraged from use in breeding. However, disc extrusion is also diagnosed in dachshunds without CDVR. The utility of the breeding programs is therefore questioned. Results A prospective study of 25 dachshunds surgically treated for disc extrusion was conducted. For all the dogs, preoperative radiographs were evaluated for detectable disc calcifications and preoperative computed tomography (CT) scans were evaluated for presence of calcified material in the vertebral canal. Postoperatively, extruded disc material was examined for degeneration and calcification by histology. Diagnostic imaging and histology were done independently. Radiographically visible calcification was identified in 17 (68.0%) of 25 extruded discs. Calcification was seen in the disc space for all these 17 discs, and for eight of the 17, there was also calcified material visible in the vertebral canal. Extruded material from all the 25 discs was found to be calcified, both by CT and histopathology. Conclusions In dachshunds with acute disc extrusion, radiographically visible calcification will frequently be found in the affected disc space, but not all affected disc spaces contain radiographically visible calcification. Using histopathology as the gold standard, a sensitivity of 0.3 (8/25) for radiography and 1.0 (25/25) for CT was found for detecting calcified disc material in the vertebral canal. Further, a sensitivity of 0.7 (17/25) was found for radiography for detecting remaining calcified material in the disc space. Thus, extruded disc material should be considered to be calcified, even in the absence of radiographically visible calcification.

Objective The aim of this paper is to provide information on the morphology and composition of gallstones based on clinical samples in order to assist paleopathologists and bioarchaeologists in recognizing their presence in archaeological contexts. Materials and Methods 270 gallstones were extracted and macerated from autopsies conducted at the Istituto di Medicina Legale in Milan (Italy) in order to simulate a dry bone recovered from archaeological contexts. Morphological, histological, and elemental variation was documented. Results Gallstones vary in size, shape, color and texture. The cross-sectional surface correlates with chemical composition and is a valuable tool for classification into subcategories of stones. Histological analysis can confirm the classification. Elemental analysis yielded a higher frequency of carbon, calcium and phosphorus. Conclusions Although identification of gallstones in archaeological contexts can be challenging, familiarity with morphological, histological, and elemental variation can assist researchers in the field and laboratory. Significance Identifying gallstones in archaeological populations will assist researchers in estimating their frequency in the past and the environmental, cultural, and biological conditions leading to their presence. Limitations Small sample size derived from a modern and limited autopsy population may minimize the types and degree of variation present in the past. Effects of climate, soil, and taphonomy were not evaluated. Suggestions for Further Research Examination of larger samples derived from diverse populations may reveal greater variation or more diagnostic aspects of stones.

Introduction: Clinical reports have been published using acellular dermal matrix (ADM) as a barrier for guided bone regeneration (GBR) procedures. To the best of the authors’ knowledge, this is the first known case report that demonstrates histologically in humans that it can successfully function in this capacity.Case Presentation: GBR, using tenting screws, bovine bone xenograft, cancellous allograft, and acellular dermal allograft as a membrane, was performed to augment a significant horizontal and vertical ridge deficiency in the area of teeth #7 and #8 of a 47-year-old female. At the time of reentry, a bone-like material was evident to the top of the screw heads. Before the placement of an implant in tooth site #8, a sample of the calcified material was removed from the edentulous ridge over tooth site #7 and was sent for histologic analysis.Conclusions: The histologic results confirmed that formation of new bone was evident, indicating that ADM likely functioned as a barrier and allowed for GBR duri...

A case of central odontogenic fibroma (COF) of the epithelium-rich type (granular cell variant) is reported. A 46-year-old female, demonstrated a multilocular, septated radiolucency below and between the roots of the teeth in 44–47 region. On microscopy the lesion revealed an odontogenic fibroma of the epithelium-rich type with areas characterized by lobules of spherical cells of varying size containing fine S-100 negative granules. In addition, scattered foci of cementoid/osteoid calcified material occurred. Based on several studies, the present authors entertain the hypothesis that supports a histiocystic origin the granular cells. Therapy consisted of curettage of the lesion. The defect was filled with spongeous bone. No recurrence occurred after follow-up of two years.

The rationale of debulking prior to stenting is to improve acute and long-term results of complex lesion angioplasty by reduction of plaque burden and/or reduction of calcified material prior to stenting, thus, allowing subsequent optimized stent-implantation and expansion. There are several registries analyzing the effect of various debulking-strategies prior to stenting in groups of selected patients and in high-risk subgroups. The majority of these studies performed DCA prior to stenting. In summary, these studies showed a reduction in restenosis rates and need for reintervention at long-term follow-up. The total TLR-rate (PCI, CABG) during a mean follow-up of 6 to 14 months is reported to be 4 to 14 %; the rate of restenosis is given as 7 to 14 %. However, until now, no large scale randomised “debulking prior to stenting” versus “conventional stenting without debulking” study has been published in detail. Several studies suggest benefit for debulking prior to stenting in complex lesion subsets, e. g., total chronic occlusions, ostial lesions, bifurcation lesions and saphenous vein grafts, but as of now, no convincing strategy has evolved.

Tumoral calcinosis (TC) is a rare condition named by Inclan in 1943 and is characterized by a large calcified mass occurring predominantly in the juxta-articular region of the extremity. This paper presents a 63-year-old man with TC of the gluteal region. Histopathological examination revealed deposits of amorphous calcified material surrounded by dense fibrous material. They were stained black with von Kossa stain. The diagnosis of TC was a source of confusion in the present research. Recently several reports reveal that the clinical and pathological features of the calcification of hemodialysis patients are quite typical of TC, but this is called calcification simulating tumoral calcinosis. We regard TC as a form of idiopathic calcification and should exclude the calcification of hemodialysis patients and small calcifications of the calcinosis cutis.

Objective: To correlate CT and MR patterns of ovarian mature cystic teratomas (MCT). Subjects and methods: CT and MR findings in 25 histologically proven ovarian MCT were retrospectively reviewed. MCT characterization at CT and MR was based on detection of fat and/or a Rokitansky protuberance. MR signal intensity and CT density numbers of fat were correlated. Results: At pathology, 24/25 tumors contained fat, 1/25 a water content, and 23/25 a Rokitansky protuberance. Twenty one MCT contained fat with a density number less than-20 HU (mean density: −95 HU) and a signal intensity superior or equal to sub-cutaneous fat on T1 images, however, only six of these had a signal intensity equal to sub-cutaneous fat on Tl and T2 images and 12 had a reversed chemical shift artifact. Three contained fat with a density number ranging from −13 to +8 HU and a signal intensity inferior to subcutaneous fat on T1 images. CT showed a Rokitansky protuberance in 21/23, containing adipose tissue in 16 and calcified structures in 21. Standard MR showed a Rokitansky protuberance in 14/23 and characterized adipose tissue in eight cases, and calcified material in six cases. Finally, CT characterized 24/25 (96%) MCT. Standard MR characterized 22/25 (88%) MCT, and standard MR with fat-suppression sequences characterized 23/25 (92%) MCT. Conclusion: Standard MR is less effective than CT in characterizing fat and has the same difficulty as CT in characterizing fat mixed with hair when its density is high. When fat cannot be identified by either technique, diagnosis of a Rokitansky protuberance is more easily made at CT than at MR.

Microliths in Araldite-embedded pieces of submandibular and sublingual glands of cat were stained in semithin sections by Methylene Blue and Azure II followed by Basic Fuchsin, and were examined in ultrathin sections by electron-microscopical X-ray microanalysis. Calcium and phosphorus were detected in substantial aggregates of crystals that were stained by Basic Fuchsin and appeared to be hydroxyapatite, but were not detected in granular material that was stained by Methylene Blue and Azure II and appeared to be organic. The polychromatic stain thus appears to be a useful indicator of calcified material. The majority of microliths in acini contained substantial aggregates of crystals, whereas the majority of those in ducts did not. This corresponds to the distribution of the glandular calcium, and suggests that microliths are variously enriched with calcium according to its local level.

Summary Freshly mixed polymerized Hydron root canal filling material, fully set AH26 and Teflon were implanted in the quadriceps muscle of guinea pigs and assessed his-tologically at 2 days, 1, 2, 3, 12 and 26 weeks after implantation. All materials were characterized by peri-implant fibrous connective tissue capsule formation. Von Kossa-positive calcific material was observed at the implant-tissue interface of Hydron implants. The amount of apparently calcified material increased with time. Inflammation was not a prominent tissue response for any of the test materials, nor was a foreign body giant cell response.

BACKGROUND AND OBJECTIVE To describe the sonographic features of senile scleral calcification using ultrasound biomicroscopy. PATIENTS AND METHODS Four patients in whom senile scleral calcifications were found incidentally on computed tomography studies underwent ultrasound biomicroscopy examination. RESULTS The senile scleral calcification was bilateral in three patients and unilateral in one patient. In all patients, the calcified material created the anterior shadowing typical of calcified lesions. The ultrasound biomicroscopy study localized the senile scleral calcification to the subconjunctival layer, superficially above the sclera, and anterior to the horizontal muscles. CONCLUSIONS This is the first description of the ultrasound biomicroscopy features of senile scleral calcification. Ultrasound biomicroscopy may serve as a good tool for the accurate localization of the plaque. [Ophthalmic Surg Lasers Imaging 2007;38:115-117.] AUTHORS From the Department of Ophthalmology (NG-C, IB, DB), Rabin Medical Center, Beilinson Campus, Petah Tiqva; the Sackler Faculty of Medicine (NG-C, IB, DB), Tel Aviv University, Tel Aviv; and the Department of Ophthalmology (EN) and the Section of Neuroradiology (YS, IIR-G), Department of Imaging, Sourasky Medical Center, Tel Aviv, Israel. Accepted for publication December 20, 2005. The authors thank Irith I. Reider-Groswasser, MD, for her contributions to this article. Address correspondence to Nitza Goldenberg-Cohen, MD, Department of Ophthalmology, Rabin Medical Center, Petah Tiqva, 49100 Israel.

Alkaline encrusted cystitis is a chronic inflammatory condition. It is rare now because of appropriate antibiotics. It is a challenging situation with regard to its diagnosis and management. We are presenting an interesting case of alkaline cystitis post transurethral resection of prostate. The management includes careful acidification of urine, curettage of calcified material, and appropriate antibiotics.

The ultrastructural features of calcification in a case of calcifying odontogenic cyst (COC) were studied. Scanning electron microscopic examination of the inner parts of the cyst wall revealed many short microvilli, and X-ray microanalysis of the high-density masses in the intercellular parts showed prominent calcium peaks, which meant that these masses were calcified materials. On transmission electron microscopic observations, many calcifications exhibited a distinctive ring formation around the periphery of a central core that consisted of an amorphous structure. These calcifications were observed with necrotic remnants of nuclear material and many identifiable mitochondria, thin fibers, and epithelial cells. The cytoplasm of ghost cells consisted of numerous short electron-dense tonofilament bundles. Needle-like structures were shown in the tonofilament bundles. X-ray diffraction analysis showed that the needle-like crystals were hydroxyapatite. It is suggested that calcification in a COC may be related to degenerative mitochondria and tonofilament bundles of ghost cells.

Pulp obliteration is a very rare occurrence that is most frequently caused by trauma. A 58-yr-old female patient had a generalized pulp obliteration that involved all maxillary and mandibular teeth. One tooth was extracted due to an extensive carious lesion and it was processed by a cutting-grinding technique. It was possible to observe the complete obliteration of the pulp chamber, which was filled in part by reparative dentin and in part by a calcified tissue with a concentric layers structure with no tubular pattern. The root canals were almost completely obliterated by an amorphous calcified material.

To the Editor: The recent article by Rockson, et al1 presents the results of a phase I trial of photodynamic therapy in patients with peripheral arterial disease. This report seems to be based on preliminary data that do not provide convincing evidence to support its conclusion, ie, that photoangioplasty holds promise as an alternative intervention for flow-limiting atherosclerosis. The lack of a control group and limiting the intervention to a single lesion that is not necessarily a flow-limiting stenosis are especially problematic. Smooth muscle cells constitute no more than 2% to 5% of the volume of the atherosclerotic plaque. Consequently, there is no basis for assuming that the cytotoxic effect of photodynamic therapy would reduce the plaque volume sufficiently to be hemodynamically significant. Even if these cells are killed and lysed, an explanation as to what happened afterward to the major extracellular components of the plaque (cholesterol deposits and fibrous and calcified material) seems necessary and important. Because there are …

The patterns on shells of mollusks display an enormous diversity and are frequently of great beauty. Shells consist of calcified material. The animals can increase the size of their shells only by accretion of new material along a marginal zone, the growing edge of the shell. Therefore, the formation of these patterns proceeds in most species in a strictly linear manner. The second dimension is a protocol of what happens as function of time. The shell patterns resemble, so to say, a space-time plot. They provide an unique situation in which the complete history of a highly dynamic process is preserved. They are thus very convenient to study general properties of pattern forming systems. Models for these patterns will be discussed. By computer simulations, it will be demonstrated that even fine details in the pattern can be faithfully reproduced.

This report describes a 31-year-old female patient with six impacted teeth. The crowns of the impacted teeth were surrounded with cyst-like lesions with a mixed internal structure and well-defined cortical borders. Microscopic examination of the specimen obtained from the follicle of the left mandibular third molar tooth revealed loose to moderately dense collagenous connective tissue with abundant calcified material and sparse epithelial islands. A diagnosis of multiple calcifying hyperplastic dental follicles was made. © 2013 by Korean Academy of Oral and Maxillofacial Radiology.

This paper presents artificial root therapeutics. The authors devised and applied clinically a new type of artificial root having different shapes according to the implanted jaw-site. We reported the results of basic studies in which fibrous tissue attached to the artificial root surface in an angled direction. We also observed by microanalyzer and Fourie-Transmitted-Infra-Red (FT-IR) analyses that cementum-like calcified material attached to the root surface (1). Two hundred nineteen artificial roots were implanted in 63 patients. The follow-up duration was from 12 to 49 months, after which favorable results were obtained.

A 35 year-old male presented with multiple asymptomatic, tense, cystic to firm, skin-colored nodules within the scrotal skin with a provisional clinical diagnosis of a sebaceous cysts of the scrotum. Fine needle aspiration cytology (FNAC) was performed and a diagnosis of idiopathic calcinosis of the scrotum was suggested as no epithelial cells were found around amorphous, basophilic, calcified material. Histopathological examination confirmed the diagnosis. We report this case for its rarity.

Seven cases of resorption in teeth have been described. Three had large internal cavities penetrating the dentine to or from the exterior. One had internal resorption in two separate locations and another had internal resorption which may have been precipitated by carious involvement of the pulp. Two cases of external resoprtion were quite dissimilar, one possibly a reaction to canal infection, the other idiopathic. Various types of calcified material were found in the areas of resorption and odontoclasts were found in one case.

The clinical and histological findings of our six cases of CEOT support the previously reported deta for this tumor. Regarding the ossification in this lesion it might be suggested that the degenerative calcified material induces dentinoid tissue formation.

A case of a high excitation threshold that occurred 2 years 5 months after the initial implantation of pacemaker electrodes is described in a girl 4 years 3 months of age. This complication was considered to be due to calcification of the platinum-iridium electrode spurs. The calcified material was shown to be a kind of apatite using the X-ray powder diffraction method. This complication is rare, but it must be kept in mind since battery longevity has markedly improved in recent years.

A case of adenomatoid odontogenic tumor involving the right upper cuspid region of a 17-year-old girl is described. In light microscopy, liminal structures and rosette-like structures were found in the parenchyma of the tumor. Electron microscopic observations revealed that the rosette-like structures were less organized than the luminal structures; the luminal structures are supposed to be associated with secretory activities including the formation of calcified material which show the apatite pattern by electron diffraction. The origin and differentiation of cells constituting the tumor are discussed.

THE ULTRASTRUCTURE of nondecalcified supragingival and subgingival calculus was studied in mature deposits. To facilitate sectioning of the embedded material, a thin reinforcing film of plastic was painted on the block. A new film was applied for each section. Light microscopy showed that supragingival calculus was heterogeneous with islets of calcified material within the covering plaque and with noncalcified areas within the calculus. Under transmission electron microscopy supragingival calculus was heterogeneous, dominated by microorganisms, small needle-shaped crystals and large ribbon-like crystals. In the covering soft plaque small crystals were often scattered in the intermicrobial matrix. In the supragingival calculus itself noncalcified microorganisms were surrounded with densely packed small crystals. There were also rosettes and bundles of large crystals. Subgingival calculus was homogeneous in light microscopy. The covering plaque contained no calcified material and only calcified material was seen within the calculus itself. Transmission electron microscopy of subgingival calculus revealed crystals of small size only. Subgingivally very few noncalcified microorganisms were seen within the calculus. The bacterial cell wall seemed to be the structure that was last calcified, both supragingivally and subgingivally.

Minor salivary gland sialolithiasis, while not common, may occur more frequently than the number of published cases suggests. An awareness of the features of this entity may aid in the differential diagnosis of submucosal masses. Because of the range of histologic findings reported, a thorough history and clinical description of the lesion should be sent to the pathologist along with the calcified material.

In seven new cases of cervical intervertebral-disc calcification of unknown etiology, all but one patient (Case 4) had an acute episode of pain in the neck, limitation of motion, and torticollis. The similarity to calcific tendinitis is suggested. Trauma or infection may initiate the symptomatic episode. Three of our patients also had calcified material in the prevertebral tissues; this did not alter the favorable prognosis. Very rapid regression of the calcification was noted in most of our patients. This syndrome is probably a much more common entity than the few reports in the literature would suggest.

Frozen sections of 75 decalcified human teeth with root surfaces exposed to the oral environment during periodontal disease were examined for the presence in cementum of “pathologic granules” (Bass 1951, Benson 1963). In 72 of these teeth granule-like formations were found in exposed cementum. In only one instance were the granules also found under an unexposed root surface. A possible explanation for this exception was presented. The cemental granules do not appear to be artifacts of fixation, decalcification, or freezing. Mineralized ground sections of exposed roots did not exhibit any structural changes resembling the granules. However, upon decalcification the granules appeared. This suggests that areas from which the granules arise are filled with calcified material.

1. 1. Nine cases have been presented in which the lesion fulfills the criteria of adenoameloblastoma. Adenoameloblastomas vary histologically from other ameloblastomas in that the epithelial component forms ductlike spaces. There is also a deposition of calcified material in all instances. 2. 2. Five occurred in females and four in males. 3. 3. Six were in the mandible and three were in the maxilla. 4. 4. Four of the patients were in a young age group—14 years of age or younger. The others were under 26 years of age, except for one, who was 43. 5. 5. There were no recurrences, metastases, or new tumor at the end of follow-up periods ranging from one month to fourteen years. 6. 6. All cases were treated by conservative surgical procedures and, according to the clinicians, the results were regarded as good.

A study was undertaken to demonstrate the apical development that occurs following debridement and filling of the root canal with a calcium hydroxide—camphorated parachlorophenol paste. Microscopic sections indicated that treatment of the teeth had stimulated the formation of granulation tissue to repair the bone destruction and soft-tissue damage effected by the use of files at and beyond the apices of the teeth. Instead of a continuation of normal root development, a repair process was observed at the apices of the treated teeth. The connective tissue in the apical area was proliferating and differentiating into a calcified material (osteodentine) which became continuous with the predentine at the apex. The repair process appeared to be attempting to seal off the apices of the treated teeth.

Thirty-one monkey teeth were subjected to surgical pulp exposures. The exposures were capped with one of four medicaments and covered with modified ZOE cement. The biologic analysis of the teeth suggests the following conclusions: 1. 1. Cresatin mixed with calcium hydroxide, used as a pulp-capping material, produced initial bridging after 1 week with only a small necrobiotic zone separating the medicament and the vital pulp. A period of 30 days was required to form a well-calcified dentine bridge covering the pulp exposure. 2. 2. Calcium hydroxide (mixed with sterile water) and Dycal resulted in similar pulpal reactions. The initial reaction was a large zone of necrosis separating the medicament and the vital pulp. The bridging that occurred at a later date was not consistent and varied from a thin fibrous barrier to a heavy amorphous calcified zone. 3. 3. Zinc oxide and eugenol cement stimulated very little bridge formation but was well tolerated by the vital pulp in direct contact with the medicament. When dentine chips were present, they would form a calcific barrier by being cemented with a calcified material. 4. 4. There was no apparent difference in the pulpal reactions of deciduous and permanent teeth.

Comparison of replica techniques and ultramicrotomy on the nacreous layer of specimens of the pelecypod Elliptio complanatus reveals marked differences in morphology. The ultrastructural differences can be induced by simple rotation of the chuck (with specimen) in the microtome and can be explained by the crystallography of the aragonite nacre. Interpretation of fine structure in ultramicrotomed densely calcified material without corroborative replica work is therefore considered extremely hazardous.

Brown patches and erosion pits were found on the inner surface of shells of Venerupis pullastra. The deformations were apparently caused by metacercariae of the trematode genus Gymnophallus. The brown calcified material seemed to be the result of unsuccessful attempts by the host to encapsulate the parasites, using calcium taken from the shell. The shells were classified into four categories according to the degree of deformation. 45.5% of the shells were deformed. Infection was found to commence when the shells were between one and two years old. 15% of the three year old shells were affected. Infection increased rapidly after the third year and reached 75% by the ninth year. Only the older specimens showed severe deformations. Infection did not affect growth of the host's shell. Two females out of 516 individuals showed probable parasitic castration caused by another type of cercariae.

Oxytalan fibers, identified by histochemical methods alone, were found embedded in the calcified material in 100 percent of the peripheral odontogenic fibromas examined. Since oxytalan fibers have been found embedded in bone in the periodontal ligament, the finding of these fibers in the calcified material of peripheral odontogenic fibromas adds considerable weight to the assumption that these lesions are of periodontal ligament origin.

A jaw tumour in a child presented diagnostic difficulties because of the presence of myxomatous elements and actively forming cementum-like calcified material. The 5-year follow-up suggests that this was an unusual benign odontogenic tumour.

Four blunt-snouted sandbar sharks (Carcharhinus plumbeus) were noted among 555 examined over a 13-yr period. Radiographs of one specimen revealed that the three rostral cartilage rods were abnormally short and failed to join at the anterior tip. The deformity appeared to be congenital. Four cases of vertebral lesions were noted in three species of shark (Carcharhinus plumbeus, Negaprion brevirostris and Odontaspis taurus). The vertebral columns had fused centra, ribs and neural arches, extra deposition and erosion of calcified material in the centra, and in one case, compression of centra. The causes of the vertebral lesions are unknown.

The literature on pulpal calcifications has been reviewed. The incidence of calcified bodies in human dental pulps is probably higher than most studies have suggested because of the problem of underreporting. Two possible modes of development exist: initial calcification of isolated pulp tissue components, which may occur anytime and anywhere in the pulp tissue, and epithelio-mesenchymal interactions during odontogenesis, which may occur only in the furcation areas and near the root sheath. The composition of the calcified bodies varies.They may be composed of “ortho” dentin, nontubular “fibro” dentin or irregular calcified material. Frequently the calcified bodies are conglomerates of these different tissues. The traditional classification of true and false denticles, based on histological characteristics, is difficult to maintain in view of this complexity of composition. Clinically, pulpal calcifications most likely are symptoms, not the cause of pathosis.

Four cases are described of a lesion affecting the lower end of the femur related to the fibrous cortical defect, but differing in that symptoms occur and radiographs show calcified material outside the line of the periosteum. A theory is put forward to account for the lesion, which is benign and will resolve without interference.

Cortical calcifications, seen on X-ray in the brain of a child suffering from leukaemia, were submitted to morphological and chemical analysis. The morphology was studied by a combination of low temperature ashing and microscanning. The calcification principally affected axons and capillary walls and consisted of spherules amalgamated into hollow cylinders. The results of chemical analysis of the calcified material were compared to those obtained in a case of Fahr's disease. The mineral composition and structure of both types of calcification were similar, but the Mn concentration was higher in the case of Fahr's disease. X-ray diffraction showed that the calcification consisted of amorphous calcium phosphate and acid calcium orthophosphate, most probably precursors of hydroxyapatite.

The process of repair in rat incisor dental pulp has been studied in 150 animals with light and electron microscopy over a period of 14 days following pulp exposure and capping with calcium hydroxide. Within the zone of injury created in the pulp by the operative procedure, inflammatory cells were present until the fifth post-operative day. The repair process had commenced by the second day with mitotic proliferation of pulp cells surrounding the wound, and over the next 2 days many of these cells migrated into the wound, displaying considerable morphological differentiation. Collagen fibrils appeared within the wound on the third day, and by the fourth day an extensive meshwork of irregularly arranged fibrils was present in the spaces between the cells. In sections of undecalcified tissue, small clusters of crystals were observed on the third day in intimate relationship to collagen fibrils at various sites throughout the wound. With progressive deposition of crystals, large expanses of calcified material of uniform appearance were formed. Decalcified sections revealed the demineralized substructure of these crystal aggregates. The earliest foci took the form of spherical structures less than 2 μ dia., having an amorphous electron-lucent peripheral zone around an electron-dense central region. By the fourth day large numbers of these foci were present throughout the wound. Growth and fusion of these small globules produced irregular masses which continued to expand by growth of the dark central region, the peripheral light layer remaining approximately the same width. Within the dark central region, collagen fibrils again became visible, and these resembled the collagen of mature dentine.

A contribution to the Discussion which followed the preceding papers. The rontgen is a unit of radiation exposure and the rad a unit of energy absorption. Biological effects of radiation are dependent on energy absorbed and so the rad is a more logical unit than the rontgen to use for the purpose of correlating biological effects with dose. As Dr. Gray said, the rad should influence our thinking and not be regarded merely as a conversion factor: for instance in connection with the relationship of dose absorbed to biological effect in bone for 250 kV radiation the “rontgen” exposure is virtually unaffected by the presence of bone but the dose in rads may be much higher numerically than what we at present think of as the dose in rontgens because of the presence of calcium. The effect of the radiation in which we are interested is on the soft tissues in the bone rather than on the calcified framework. The Haversian canals are lined by endothelial cells which lie adjacent to calcified material, and osteoblast...

Summary Nephrocalcinosis was diagnosed as an incidental histopathological finding in 2 Sprague-Dawley rats of ISO g bodyweight, The calcified material was located along the entire corticomedullary junction. Dietary and other causes of nephrocalcinosis are discussed. Nephrocalcinosis is commonly found in older rats, but only infrequently reported in young ones, although the lesions have been seen in animals as young as 2-3 months of age (Casey, Ayers & Robinson, 1978; Paterson, 1979). This report describes the incidental finding of nephrocalcinosis in young Sprague-Dawley rats.

My purpose in this paper is to stress' and reemphasize the danger of using calcium gluconate for intramuscular injection in infants. In 1936 there were two reports which recorded the effects of calcium deposition in the tissues of 2 infants who had received the calcium intramuscularly. Tumpeer's case 1 was that of an infant who weighed 6 pounds 13 ounces (3.1 Kg.) and received 9 cc. of 10 per cent calcium gluconate intramuscularly on the third day of life. At the age of 5 weeks x-ray examination demonstrated a radiopaque substance in the thigh and buttocks where the injection had been made. A week later there was a slough of the tissue, with the extrusion of calcified material which was identified as calcium phosphate. By the fourth month of life an x-ray of the region was normal. Von Hofe 2 reported the case of an infant who had received