Pregnancy and progeny in rats treated with the pyrrolizidine alkaloid fulvine

The pyrrolizidine alkaloids are naturally-occurring plants toxins which are considered significant in the etiology of certain liver diseases, particularly in some tropical and sub-tropical regions. Fulvine, a hepatotoxic alkloid present in the medicinal herb Crotolaria fulva, was observed to be fetotoxic and highly teratogenic in rats. The occurrence of fetal resorptions showed a dose-effect relationship. The highest incidence of developmental defects was induced by fulvine at a dose-level of 80 mg/kg which in other studies produced significant chromosomal damage. Microscopic examination of fetal liver, following maternal exposure of fulvine, did not reveal hepatic lesions.(Summary)

Gliomatous teratoma of the tongue: report of a case

A tumor measuring 21/2 x 1 x 1 cm in the tongue of a 6 week-old child and present from birth proved historically to be a teratoma with pre-dominantly glial tissue. The authors have found only one similar case described previously (AU)

Osteoclasts in bone resorption: an experimental model

Osteoclasts are frequently, perhaps invariably, associated with resorbing surfaces of bone. Studies have been carried out in animals stained intra-vitally with alizarin red, supravitally with neutral red, and in controls, to determine criteria for resorption and the frequency of association of osteoclasts with this process. In these experiments, a constant association was found between the presence of osteoclasts may be utilised as "target areas" in order to test factors affecting osteoclast function (AU)

Alizarin red in the study of the apposition and resorption of bone

Alizarin red is given intraperitoneally in dosages of 50-200 mg per kg. It stains visibly only one generation of bone. Its deposition is studied in gross specimens and in undecalcified sections, and is controlled by comparison with serial decalcified sections. Apposition of white bone can be followed in relation to red bone on periosteal surfaces (where it presents appearances corresponding to different growth rates), on endosteal surfaces, in osteons, and in the interstitial compaction of cancellous bone. Red surfaces may be sites of deposition, stasis, or resorption. Measurements may be made from red lines, provided microscopic control is available. Removal of red bone implies resorption. It is closely correlated with the presence of osteoclaasts in control sections and with areas of surface pitting grossly. Resorbing surfaces may be precicely delimited by studing a graded series of animals. Whole surfaces or zones of stained bone are seen to drift to other situations, undergoing resorptive dissolution or consolidating anew as they move relative to the newer layers. The usefullness of the dye lies in its simplicity of administration, its ready visibility, and the fact that its persistence in bone enables the fate of areas of bone to be followed over long periods. The preparation of undecalcified sections is a problem common to many other techniques

Wolff's law and the problem of muscle attachment on resorptive surfaces of bone

During the growth of a bone, outer (periosteal) surfaces in many areas undergo normal remodeling processes involving resorptive removal. Attachments of muscles commonly occur on such outer resorptive surfaces.The cortex in these regions grows in an inward direction by bone deposition on endosteal surfaces. In some areas of a bone, a portion of muscle can be inserted onto adepository surface, but other parts of the same muscle may be attached on to an adjacent resorptive surface. It has been generally assumed that the pull of a muscle acts to directly stimulate deposition of new bone, and that attachments of muscle are thereby responsible for determining the gross morphology of a whole bone. In view of the foregoing considerations, a re-evaluation and an expansion of this concept is now needed. Muscle pull, in many regions of a bone, can be associated with normal cortical recession (involving surface resorption) as well as with outward bone deposition. (AU)

The role of soft tissues in skull growth in rabbits

The vault is said to expand centrifugally, following expansion of the brain or of an equivalent fluid mass. The bones are carried passively outwards. However, the frontal bone shows, simultaneously, sutural growth: resorption in parasutural areas endocranially and in the olfactory fossa: stasis or slow erosion ectocranially over the eminence, differential endocranial and estocranial deposition, and differential deposition and resorption on the orbital plate; and a pronounced postolfactory ridge of endocranial deposition. Cartilage is said to act as "pacemaker", its interstitial growth and turgidity enabling it to thrust bones in particular directions. Pressure on bone familarly leads to resorption. Two areas on the frontal bone in contact with the enlarging cartilaginous ethmoid show, respectively, resorption and deposition. The response to thrust is not simple. Can muscular pressure affect the form of the braincase? The squamosal bone forms a bed for muscles: (1) the temporalis (a) attached to its postzygomatic surface above, fibres nearly horizontal: (b) attached to its orbital surface, fibres vertical; (c) its tendon related to the upper aspect of the zygomatic process root; and (2) the lateral pterygoid related to the paracondylax fossa and inferior margin. Surface (1) (a) shows deposition; (1) (b) marked resorption; (1) (c) shows stasis early, slow deposition later - a rate of deposition increased by temporalis section. Surface (2) shows resorption above, with continuous osseous drift inwards, and below, deposition. Further experiments are needed to elucidate the cause-effect relationships between muscle and bone. The contribution of the sense capsules to the overall form of the cranium has been neglected. The cribriform plate is displaced endocranially, as is the posterior part of the orbit, where it forms neurocranial wall. The circumferential growth of the ear capsule causes periotic encroachment upon the cranial cavity. Thus brain growth must be compensated for at areas other than these (AU)