The study of caries prevalence in children in a developing country.

This study has shown that prevalence of dental caries in a rural section of a developing country is related to age, socioeconomic status, and specific location. Caries prevalence is also directly correlated with family consumption of sugar. No correlation could be found, however, with regard to sex. Further study should be conducted on the relationship of individual practices (sugar consumption and hygiene) to caries-prevalence. In particular, data could be collected on practices in the communities where the school surveys were conducted in order to define the factors underlying the high prevalence of caries in some and lower prevalence in the others. The fluoride levels in the drinking water and the possible effect of hypoplasia on caries-prevalence in primary teeth are topics for further research. The latter condition should be investigated to determine the cause of its high prevalence, which might be an important consideration in future dental health interventions. Dental health education should be directed as soon as possible to communities, such as those in this study, where dental caries prevalence and sugar consumption are still low. It is usually more successful to encourage the adoption of new behaviors and attitudes or redirect them in a similar direction than to ask people to give up a valued behavior. In this situation, it would be preferable to encourage continuation and effective use of traditional hygiene methods and the current low levels of sugar consumption than to wait until sugar consumption is likely to become entrenched at high levels and traditional hygiene practices abandoned.

The structure and development of the pineal complex in the lanternfish Triphoturus mexicanus (family mycotphidae).

The pineal complex of the lanterfish Triphoturus mexicans was studied by light and electron microscopy. Receptor, supportive and ganglion cells were identified in the pineal end-vesicle. The presence of receptor cells and the prominent pineal window strongly suggest a photoreceptor function. Numerous unmyelinated nerve fibers were also found in the end-vesicle. These converge to form part of the pineal stalk. Two kinds of cells (Types I and II) were distinguished in the dorsal sac, which is very well developed. Type I cells are non-ciliated ependymal cells and contain large parcels of glycogen. Type II cells contain large lipid-like inclusions and a distinct band of filaments around the entire periphery of the cell. Receptor cells appear very early in the development of T. mexicanus. They seem to originate from ependymal cells lining the roof of the third ventricle.