A morphological and histochemical study of the developing tongue musculature in the mouse: its relationship to palatal closure.

Some question exists concerning the ability of the embryonic tongue to undergo reflex movements at the time of palatal closure (15.5 days of development). Functional motor endplates are prerequisite for such movements to occur. Light and ultrastructural cytochemical methods were employed to elucidate the morphology of neuromuscular relationships in the developing mouse tongue. The A/Jax mice used in the experiments demonstrated a 12-20% incidence (seasonal variation) of spontaneous cleft palate, allowing a correlation between normal and teratological processes. Organized myofibrils were first seen in tongues of normal and spontaneous cleft lip-cleft palate (SCL-CP) specimens at 14.5 days of development. The thiocholine technique of Karnovsky and Roots was used to demonstrate acetylcholinesterase (AChE) activity at the light microscope level. The Lewis and Schute method was used for ultrastructural localization of this enzyme. Tissues from normal and SCL-CP specimens from 12.5 to 20.5 days of gestation failed to show differences in amounts or distribution of AChE activity. AChE activity was seen as early as 14 day's gestation. Electron microscopic studies demonstrated reaction product in the endoplasmic reticulum and nuclear envelope of developing myoblasts. AChE activity at the developing neuromuscular junction and the occurrence of myofilaments preceded palatal closure by several days. Based on these morphological and histochemical findings the tongue of normal and SCL-CP embryos appears capable of responding to a neurogenic stimulus at the time of palatal closure. The findings suggest that the tongue of animals exhibiting a spontaneous cleft palate is not actively involved in the etiology of this condition.     

Taurodontism: A biometric study

This study has been carried out in order to clarify various aspects of the phenomenon known as taurodontism. Samples of both taurodont and non-taurodont teeth were measured and statistical analyses were performed on the resultant data from which various conclusions may be drawn. The most important conclusion is that this phenomenon may be defined metrically. The distributions have shown that the taurodont trait grades into the normal and it is quite difficult to make a subjective judgment at the low end of the taurodont range. It is for this reason that an accurate mathematical means for performing this task is so invaluable. The question of the nature of cuneiform single rooted molars was also investigated, and they were found not to be true taurodonts although the statistical procedure classed them as such. It was demonstrated that through the construction of simple plots these teeth could be eliminated from any group classed by analysis as taurodonts. Various metrical attributes were evaluated with respect to their ability to distinguish taurodonts, and two were found to be satisfactory for this purpose in most cases. Certain changes in molar morphology regarding caries and age were also investigated.     

Morphology of defense glands of the opilionids (daddy longlegs) Leiobunum vittatum and L. flavum (Arachnida: Opiliones: Palpatores: Phalangiidae)

Opilionid defense glands consist of 0.5 × 0.9-mm sacs attached to the underside of low tubercles located on the dorsal side of the cephalothorax, posterior to the first pair of legs. Each gland opens via an elongated slit, located in the posterior floor of a crater that is situated at the summit of the tubercle. The center of the sac, called the reservoir, is lined by a cuticle consisting of epicuticle and endocuticle which is continuous through the slit with the exoskeleton. The layers of cuticle vary in thickness with different locations in the gland. A hemocoelomic (basement) membrane, 0.5–1, μ thick, forms the boundary between glandular cells and hemocoel. The gland has a nonsecretory portion consisting only of cuticle-supporting cells and a secretory portion consisting of secretory and cuticle-supporting cells. The cuticle lining the reservoir in the secretory area is broached by many cuticle-lined ductules, each of which drains an isolated intercellular space called the intercalated cistern. This in turn drains microvilli-lined canaliculi located between and extending into secretory cells. The cisterns are devoid of microvilli. Secretory cell cytoplasm contains a Golgi apparatus, many free ribosomes, rough endoplasmic reticulum (RER), two types of granules (speckled and dense), and mitochondria. Speckled granules are partially filled with fairly large particles and are found in association with the Golgi apparatus. They also surround canaliculi into which they empty. Dense granules are packed with very small particles, have a gray homogeneous appearance, and are scattered throughout the cytoplasm. Mitochondria containing matrix granules tend to scatter throughout the cytoplasm but are concentrated around canaliculi.     

Tonerzeugung durch schwingenden Membranen bei Ameisen (Plagiolepis,Leptothorax, Solenopsis)

Ohne Zusammenfassung     

The ecology of the female Haematopota insidiatrix austen (Diptera, Tabanidae) in Southern Rhodesia

The habitat of H. insidiatrix, in the region of Main Camp, Wankie National Park, is considered briefly. The seasonal occurrence of the fly is studied and its activity throughout the day. Comparisons are drawn with previous work in colder climates.

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Zusammenfassung Die Heimat von H. insidiatrix, in der Nähe von Main Camp, Wankie National Park, wird kurz betrachtet. Das jahreszeitliche Vorkommen der Fliege und ihre Aktivität im Tagesverlauf werden untersucht. Die Resultate werden mit denen von früheren Untersuchungen in kälteren Klimaten verglichen.

     

Traditional treatment for mental illness in Africa: A review

The publication of The Quest for Therapy in Lower Zaire (University of California Press) by John M. Janzen (with the collaboration of William Arkinstall), and African Therapeutic Systems (Crossroads Press), edited by Z. A. Ademuwagun, John A. A. Ayoade, Ira E. Harrison and Dennis M. Warren, calls attention to recent research findings which indicate that mentally ill persons, particularly schizophrenics, may recover more rapidly and fully in non-industrialized societies than they do in industrialized ones. The books by Janzen and Ademuwagen et al. will be examined as contributions to a growing body of information on native African therapeutic practices. Evidence relating to the apparently benign course of psychosis in Africa will be examined, and various explanations for this pattern will be evaluated. Finally, some guidelines for future research will be suggested.     

Effects of glycerol on microtubule polymerization kinetics

Steady state and kinetic studies of polymerization of purified microtubule protein show little effect of glycerol on the steady state level of polymerization, as demonstrated by measurements of critical concentration. The rates of polymerization and depolymerization are slowed in the presence of glycerol. This data indicates that the stabilization of microtubules by high glycerol is largely a kinetic effect rather than a shift in equilibrium. However, the apparent critical concentration for microtubule polymerization from crude brain homogenate is substantially higher in the absence of glycerol, and glycerol appears to protect microtubule polymerization against the action of endogenous inhibitors.