Skeletal Ultrastructure in some Tubuliporine Cyclostome Bryozoans

The ultrastructure of the calcareous skeleton is described in twenty–one species of recent tubuliporine cyclostome bryozoans, using field emission SEM. The succession of skeletal fabrics in interior walls may be classified into four different fabric suites. The first–formed part of the calcitic skeleton in all species for which it has been observed is a precursory fabric of tiny, wedge–shaped crystallites. This is succeeded in about half of the species studied by a fabric of transverse fibres, followed by foliated fabric and often semi–nacre (fabric suite 1). Most of the remaining species lack transverse fibres and have interior walls largely comprising semi–nacre (fabric suite 2). A few species have skeletons consisting of predominantly distally–oriented, irregularly or regularly foliated fabric (fabric suite 3). A single species has a skeleton of proximally–oriented foliated fabric (fabric suite 4). Basal exterior walls in all species have a precursory fabric of tiny wedge–shaped crystallites without a strong preferred orientation, deposited directly upon the organic cuticle, followed by a layer of planar spherulitic structure, which in turn is succeeded by a similar fabric to that developed in the interior wall of the species concerned. Outermost layers of frontal exterior walls exhibit one of the following combinations of three fabrics: an outer layer of (1) finely granular or wedge–shaped crystallites; a thin dense granular layer followed by (2) distally accreting planar spherulitic fabric., or (3) obliquely accreting planar spherulitic fabric growing partly towards the midline of the frontal wall. Terminal diaphragms usually have outer layers dominated by planar spherulitic ultrastructure with centripetal growth directions. The fabric suites present in tubuliporines encompass most known fabrics found in the other cyclostome suborders and support the notion that this species–rich suborder occupies a central position in cyclostome evolution.     

Ultrastructure of interstitial cells of Cajal at the gastro-oesophageal junction of the monkey (Macaca fascicularis)

The ultrastructure of the interstitial cells of Cajal (ICC) in the oesophagus of the monkey resembled that described in the oesophagus of other mammalian species but differed in their paucity and almost lack of smooth endoplasmic reticulum, caveolae and filaments. The plasmalemma of the ICC was in close contact (20- to 30-nm gaps) with that of smooth muscle cells. This may occasionally take the form of a desmosome, but gap junctions have not been observed. Vesiculated axon profiles, containing large granular or agranular vesicles were in close contact (20- to 30-nm gaps) with the plasmalemma of ICC. In a few vesiculated profiles a presynaptic density could be recognized. The intercalation of the ICC between the vesiculated axon profiles and the smooth muscle cells suggest a role in oesophageal motility. Between 3 and 21 days following bilateral vagotomy some ICC showed regressive changes such as increased electron density and shrinkage of the cytoplasm, crowding of the organelles and dissolution of the nuclear chromatin material. Axon profiles in the vicinity of the affected ICC contained glycogen granules suggesting injury. In late stages, the number of ICC and smooth muscle contacts was reduced. The results suggest that the vagus nerves exert a trophic influence on the ICC and that the intercellular relationships between ICC and smooth muscle cells possess a degree of plasticity. It is tentatively suggested that these vagal effects may be mediated via the oesophageal myenteric ganglia.     

A mechanism for passive mandibular depression

Retention of a retromandibular space has necessitated developing a system of mandibular protrusion in hominid species. It is possible that mandibular protrusion can be effected by a single muscle-the lateral pterygoid-and the motion controlled by the excentrically placed mandibular suspensory ligaments. The elasticity of the ligaments produces an integrity maintenance force between the articular condyle and eminence which is normally of minimal size. Excessive craniofacial flexion, or the retention of a juvenile configuration of the mandible, could result in increasing this integrity maintenance force and cause crepitation and clicking. Ajustment of the ligaments could reduce these pathological manifestations.     

Exocoelomic internal hernia: elucidation of Papez's concept.

Two internal herinias of the intestines were found in adult males. One was a large translucent avascular membranous sac contining the small intestine from the duodenojejunal flexure to a point 6 in. proximal to the ileocaecal junction. The other was a peritoneal sac enclosing the small intestine, appendix, caecum and 6 in. of the ascending colon. The mesenteric and colic vessels were normal. Both hernias conformed to PAPEZ's concept of the so-called paraduodenal hernia that the hernial sac is derived from the umbilical coelom. The authors suggest that most of the so-called paraduodenal hernias are derived from the embryonic umbilical peritoneal diverticulum rather than from the peritoneal recesses or mesentery of the colon.     

Effect of menthol on human temperature sensitivity

Application of 1% methol, which, along with cold, activates specific thermosensitive ionic channels, changes the number of functioning cold receptors on the skin of the forearm similarly to the cold exposure test; however, it does not affect the number of heat receptors and does not significantly change the threshold of cold sensation. Group variants of responses to menthol that indicate individual differences in the sensitivity of skin receptors to the effects of methol and cold have been found. The results obtained give grounds to suggest that, from the variant of response to menthol (a decrease, increase, or absence of changes in the number of functioning cold receptors 5 min after menthol application), it is possible to predict specific features of response to cold.     

New skeletal tuberculosis cases in past populations from Western Hungary (Transdanubia)

The distribution, antiquity and epidemiology of tuberculosis (TB) have previously been studied in osteoarchaeological material in the eastern part of Hungary, mainly on the Great Plain. The purpose of this study is to map the occurrence of skeletal TB in different centuries in the western part of Hungary, Transdanubia, and to present new cases we have found. Palaeopathological analysis was carried out using macroscopic observation supported by radiographic and molecular methods. A large human osteoarchaeological sample (n = 5684) from Transdanubian archaeological sites ranging from the 2nd to the 18th centuries served as a source of material. Spinal TB was observed in seven individuals (in three specimens with Pott's disease two of which also had cold abscess) and hip TB was assumed in one case. The results of DNA for Mycobacterium tuberculosis were positive in seven of the eight cases identified by paleopathology, and negative in the assumed case of hip TB. However, the molecular results are consistent with highly fragmented DNA, which limited further analysis. Based on the present study and previously published cases, osteotuberculosis was found in Transdanubia mainly during the 9th-13th centuries. However, there are no signs of TB in many other 9th-13th century sites, even in those that lie geographically close to those where osteotuberculous cases were found. This may be due to a true absence of TB caused by the different living conditions, way of life, or origin of these populations. An alternative explanation is that TB was present in some individuals with no typical paleopathology, but that death occurred before skeletal morphological features could develop.