[Prevalence of non carious dental lesions in the department of Dakar]. / Prevalence des lesions dentaires non-carieuses dans le departement de Dakar.

Non carious dental lesions are destructions of dental external surfaces originating from non bacterial cause in opposition to dental caries. We distinguish 5 types of non carious dental lesions: attrition, abrasion, abfraction, erosion and demastication. These lesions may be pathological or physiological. Data dealing with them are not very numerous in the literature. Their study shows a real interest in conservative dentistry because of problems both aesthetic and functional they set We carried out an epidemiological trial in the department of Dakar with as aim providing data on the prevalence of these lesions. Our results have disclosed the following rates of prevalence: 60% of attrition, 25,55% of abrasion, 7,22% of abfraction, 5,55% of demastication and 1,68% of erosion. The results indicate once more the importance of the need for clinical evaluation of those dental lesions.

The role of luteal steroid hormones in the regulation of the estrous cycle of high fecundity Olkuska sheep.

The study was undertaken to investigate the steroid hormone production by sheep luteal cells. Corpora lutea were collected from 30 Olkuska sheep on Days 3, 6, 9, 12 and 15 of the estrous cycle during the reproductive season. In Experiment 1, steroid hormone concentration was estimated in extracts of CL. In Experiment 2, luteal cells were cultured in vitro for 24 h. Luteal cells isolated on Days 9 and 12 secreted high amounts of progesterone and androgens but smaller amounts of estradiol. Concentration of these steroids in CL extracts collected on the same days showed the same trend. In CL harvested on Day 15, a decrease in androgens and progesterone as well as a significant increase in estradiol were observed in culture media and in extracts. Judging from the high amounts of estradiol and low amounts of androgen observed at the end of the luteal phase, we speculate that the steroid hormones secreted by the regressing CL may play an active role in the regulation of the estrous cycle in the Olkuska sheep with autocrine influence on the luteal activity or a possible paracrine action on follicular growth. In the third Experiment, the possibility of heterogeneity in the multiple corpora lutea population of prolific Olkuska sheep was investigated. Differences were found in the level of progesterone and estradiol secretion by individual corpora lutea recovered from the same animal, which also varied in terms of weight. This is the first study which shows the existence of intra-ovarian and individual heterogeneity between corpora lutea recovered from ewes during the normal estrous cycle.