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Biomedical subjects

J Merzel

Publications and source records attributed to J Merzel.

16 recordsLinked to original sources
PubMed1991

In vitro penetration of 125I-amelogenin into the enamel and enamel organ of rat incisors.

This work attempted to introduce pre-labelled intact amelogenins into developing rat enamel in vitro. The intention was ultimately to trace the fate of such proteins in the developing enamel matrix and to examine the effect of these and other molecules on ameloblast behavior. The penetration of 125I-amelogenin (25 KDa) directly into the young enamel of rat incisors, in vitro, keeping the enamel organ intact is described. The enamel (an extension approximately 8 mm from the apical end of the tooth) together with the enamel organ, was separated from the underlying dentine and placed over a strip of filter paper covering a well of micro-culture slide filled with Eagle's medium containing 125I labelled amelogenin and incubated at 37 degrees C. The enamel faced the strip of filter paper and so was adjacent to the medium. After 1 h pieces were either washed in cold medium, fixed and embedded in Epoxy-resin, or incubated in cold medium for another 1 to 10 h at 37 degrees C before embedding. One-micron thick sections were processed for autoradiography and the results showed a decreasing gradient of silver grain concentration from the dentino-enamel junction towards the enamel organ. It is expected that by determining the nature of the labelled material incorporated into the enamel and enamel organ the fate of amelogenins could be better understood.

Ameloblasts↗
PubMed1989

[Histochemical detection of glycoproteins and glycosaminoglycans in the respiratory mucosa of albino rats during estrous cycle, pregnancy and puerperium].

In this work we attempted to detect, with histochemical methods, the possible modifications in the mucus of the respiratory mucosa of albino female rats during estral cycle, pregnancy and puerperium. Based on its results, it was possible to conclude that: a--There were no modifications in the nature of the epithelial and supraepithelial mucus during the studied periods: b--The Alcian Blue staining from lamina propria is absent during pregnancy and present during puerperium.

Animals↗
PubMed1988

The effects of cerebral hemidecortication on the eruption rate and uptake of [3H]-glycine by the periodontal ligament of the rat incisor.

Hemidecortication, which consists of removing one cerebral hemisphere, leaving intact the thalamus and hypothalamus, affects the hypothalamus-hypophyseal axis producing hypothyroidism. Hemidecorticate rats showed a significant decrease in the weekly eruption rate of the upper incisors and partial recovery after the administration of thyrotrophin-releasing hormone (TRH). The uptake of [3H]-glycine, 1 and 4 h after a single injection, shown by radioautography, was 25 to 50 per cent higher in the periodontal ligament of the experimental animals. Most of the labelled material was non-collagenous proteins because only 20 to 30 per cent was removed by collagenase.

Animals↗
PubMed1988

Thyroid function in hemidecorticate rats.

1. Thyroid function was evaluated in hemidecorticate (HD) and control (C) rats by determining serum T3 and T4 levels and the development of incisors and mandibles and through analysis of various histological features of the thyroid such as follicle size, colloid droplet content and [3H]-glycine uptake by follicular cells. 2. HD animals presented normal levels of circulating T3 but significantly lower T4 levels. 3. There was slight atrophy of the gland in HD animals and fewer colloid droplets were present in the cytoplasm of the follicular cells in this group, indicating a reduction in the breakdown of thyroglobulin. [3H]-glycine uptake by HD indicated that the rate of thyroglobulin biosynthesis was not altered in the experimental animals. 4. The growth of mandibles (weight) and incisors (weight and length) was reduced in HD compared to the control animals. 5. These results suggest that hemidecortication causes mild hypothyroidism (trophoprivic type) probably by affecting hypothalamic function.

Animals↗
PubMed1985

Effect of vinblastine on the cell cycle and migration of ameloblasts of mouse incisors as shown by autoradiography using 3H-thymidine.

The effects of vinblastine on the cell cycle and the migration of ameloblasts were studied in the lower incisors of mice by labelling the cells with 3H-thymidine ([3H]TdR) and radioautography. A group of mice received 2 micrograms/g of body weight vinblastine intraperitoneally and 6 hr after these animals and those of a control group were injected with 1 microCi/g body weight of [3H]TdR, and sacrificed at time intervals from 0.75 hr to 15 days. The generation time of ameloblasts in the progenitor compartment was 14.8 hr in animals treated with vinblastine and 17 hr in the controls, using the FLM curve method; with the grain dilution method the duration was respectively 29.25 hr and 25.96 hr. The thymidine labelling index of the treated animals was 50% higher than the controls. The velocity of ameloblast migration, determined either by the displacement of the most incisally labelled cell or by the grain dilution method, was lower in the experimental group (2.48 cell positions/hr and 9.18 microns/hr respectively) as compared with the control (3.21 cell positions/hr and 18.88 microns/hr respectively). The results on the ameloblast production rate are contradictory but the slowing down in the velocity of cell migration is compatible with a decrease of the rate of cell production in the progenitor compartment as a vinblastine effect.

Ameloblasts↗
PubMed1977

Distribution of epithelia and glands of the nasal septum mucosa in the rat.

A histotopographic study of the nasal septum mucosa in rats was made using semi-serial sections stained with PAS-hematoxylin, reconstructed in form of maps representing the structure in a sagittal plane. The stratified squamous, respiratory and olfactory epithelia and Masera's organ cover 14.8, 43.6, 41.6 and 1.8%, respectively, of the septal surface (117.1 mm2). In the vestibular region, only ducts of PAS-negative glands of the respiratory region are found, and below the septum there is the infraseptal gland with PAS-negative acini. In the respiratory region, PAS-negative acinous glands form two groups: the superior and the inferior one occupying 10.5 and 1.5%, respectively, of the septal area. PAS-positive acinous glands are in the inferior half of the respiratory region and in a small anteroinferior portion of the olfactory region. Besides goblet cells broadly distributed, the respiratory epithelium presents scattered intraepithelial PAS-positive glands which are concentrated in the anterior portion and close to the nasopharyngeal duct. In the olfactory region prevail Bowman's PAS-positive glands which are also present in the mucosa of Masera's organ, but are not seen in the olfactory mucosa of Jacobson's organ. In the latter, PAS-positive glands are found in the respiratory mucosa. Globular leukocytes, cells of connective tissue origin, are constantly infiltrating the superior regions of the respiratory and olfactory epithelia, being more numerous in female rats.

Animals↗
PubMed1976

Homogenous and heterogenous bone implants preserved by formaldehyde: a histologic study.

Small bone sticks from a rat and a dog, fixed in formaldehyde from one to several weeks, were used as homografts and heterografts in defects created in the mandibles of rats. The animals were killed 30, 60, 90, and 150 days after the graft implantation procedure. Histologic study showed that although the homografts induced a distinct osteogenic activity and were incorporated by the host in less than 90 days, the heterografts behaved as foreign bodies and became encapsulated by connective tissue and remained unresorbed up to 150 days. Therefore, the clinical applicability of formaldehyde-fixed homografts should be considered.

Animals↗