Histochemical observations of protein-bound amino groups in human developing deciduous teeth

Summary Human developing deciduous teeth were studied by histochemical methods for protein groups; dinitrofluorobenzene (DNFB) H-acid stain for tyrosine histidine and tryptophan, coupled tetrazonium reaction with pre-iodination for histidine, diazotization and Millon's reaction for tyrosine revealed strong staining in the granular precursor of ameloblastic cytoplasma, pre- and young enamel layers. But only alloxan-Schiff stain showed a more intense stainability in the dentin matrix and pre-enamel than the young enamel matrix. The reaction of sulfhydryl and disulfide groups was observed in the matrix-forming ameloblast and Tomes' process with some variation of staining in the enamel matrix. The present histochemical results of protein groups in the enamel matrix were similar to those of the cornified layer of skin.Ameloblasts moderately stained with DNFB H-acid, coupled tetrazonium and alloxanschiff reaction were similarly stained in both matrix-forming stage and reduced stage. Increasing stainability of odontoblasts was limited in the matrix-forming stage.Pronounced changes of staining intensity in the enamel matrix for protein groups were found especially in the intra-rod organic substance with progress of mineralization and growth of deposited mineral crystallites, starting from the region of apex of cusp, parallel to the dentino-enamel junction.The stainability of the dentin matrix for protein groups increases following decalcification, and non-decalcified dentin was weakly stained for the alloxan-schiff method, coupled tetrazonium reaction, sulfhydryl and disulfide method.     

Histochemical studies of developing human fetal small intestine

Summary The histochemical characteristics of absorptive and mucus-producing cells have been described in 16 specimens of small intestine from human fetuses between 7 and 22 weeks of age. In the youngest specimens a slight to moderate reaction was found for all enzymes examined which included those known from biochemical or ultrastructural studies to be located predominantly in Golgi apparatus (thiamine pyrophosphatase), surface membrane (alkaline phosphatase, adenosine triphosphatase, leucine aminopeptidase), lysosomes (acid phosphatase), and mitochondria (succinic dehydrogenase). Mucus granules of somehat unusual location and staining properties were also found at this time. A progressive intensification of a majority of these histochemical reactions was observed between 3 and 6 fetal months.These findings indicate that the histochemical apparatus for degradation and absorption of nutrients and for elaboration of protein and mucus is already well established in the human fetus by the end of this 6 month period. It is not known, however, whether these activities occur in utero or whether they contribute significantly to fetal nutrition.     

Histochemical studies on the developing adrenal gland of Gallus domesticus

Summary The distribution of adrenaline, noradrenaline, aliesterases and non-specific cholinesterases in the cortical and medullary cells and that of ascorbic acid in the cortex have been studied histochemically in sections of adrenal glands from embryonic, juvenile and adult chicken. Both the catecholamines are secreted by the embryonic medulla from the 11th day of incubation but noradrenaline is the more abundant of the two hormones at all stages and it is secreted by the majority of chromaffin cells. There is a tendency for the adrenaline-secreting cells to predominate in the subcapsular layer of the medulla. Both types of chromaffin cells reveal considerable cholinesterase activity consistently from the second half of incubation period onwards.A high concentration of aliesterases and ascorbic acid are developed and maintained in the cortical cords from the time the cortex begins secretory activity, namely, the 10-day incubation stage. Lower concentrations of cholinesterases are also present in the cells of the cortex. The cords of the peripheral zone of cortex show higher concentrations of both the enzymes and ascorbic acid than those of the central zone.From a thesis submitted to McGill University, Montreal, Canada in 1963 in partial fulfillment of the requirements for the degree of Doctor of Philosophy. The work was done during tenure of a Canadian Commonwealth Scholarship.     

Histochemical and electron probe analysis of secretory ameloblasts of developing rat molar teeth

Calcium was not found in secretory ameloblasts and stratum intermedium cells when treated with OsO4-pyroantimonate or when surfaces prepared by fracturing fresh, rapidly frozen, developing molar tooth germs were subject to electron probe X-ray analysis. Pyroantimonate reaction product, considered to be calcium, was found in mitochondria of enamel organ cells which were first placed in a bath containing calcium and potassium. The plasma membrane was disrupted in cells ehich showed mitochondrial localization of reaction product. The results provide no data which indicates that enamel organ cells have a direct, active role in the movement of calcium into the enamel. Rather, it is suggested that the secretory enamel organ might serve as a selective barrier in regulating the initial mineralization of enamel.     

Histochemical and electron probe analysis of secretory ameloblasts of developing rat molar teeth

Summary Calcium was not found in secretory ameloblasts and stratum intermedium cells when treated with OsO₄-pyroantimonate or when surfaces prepared by fracturing fresh, rapidly frozen, developing molar tooth germs were subject to electron probe X-ray analysis.Pyroantimonate reaction product, considered to be calcium, was found in mitochondria of enamel organ cells which were first placed in a bath containing calcium and potassium. The plasma membrane was disrupted in cells which showed mitochondrial localization of reaction product.The results provide no data which indicates that enamel organ cells have a direct, active role in the movement of calcium into the enamel. Rather, it is suggested that the secretory enamel organ might serve as a selective barrier in regulating the initial mineralization of enamel.     

Histochemical distribution of hydroxysteroid dehydrogenases in kidney and liver

Summary Mouse, rat, hamster, guinea pig and sheep kidneys and foetal human, adult male and female human, mouse, rat, hamster and guinea pig livers were examined for hydroxysteroid dehydrogenase activity.3-Hydroxysteroids were utilised by all tissues, including neonatal mouse kidney, but the 5-configuration was a more suitable substrate than the corresponding 5-steroid. Both N.A.D. and N.A.D.P. were suitable cofactors.Only trace 3-hydroxysteroid dehydrogenase activity was demonstrable in renal tissue, however liver possessed a higher level of activity and lanosterol, a precurser of cholesterol, was an especially suitable substrate possibly indicating that the liver is capable of synthesising cholesterol.6-Hydroxyprogesterone was poorly utilized by renal and hepatic tissue and N.A.D. was found to be the only cofactor suitable for this reaction. All the tissues, possessed 11-hydroxysteroid dehydrogenase activity. In the kidney, this enzyme occurred in the collecting tubules. It was further noted that in mouse kidney 11-hydroxysteroid dehydrogenase was absent at birth but appeared within the first fourteen days. Activity with 11-hydroxysteroids was observed to be more prominent in the liver of male animals and this pattern was also found with 3-, 3-, 16- and 16-hydroxysteroids, all of which are confirmed by previous biochemical findings.Renal tissue was not capable of utilizing the 16-hydroxysteroid in contrast to liver which could use this substrate fairly well. 16- and 17-hydroxysteroid dehydrogenases were demonstrable in the livers of all species and in all kidneys. The 20-hydroxysteroid was only poorly utilized by hepatic tissue and not at all by renal tissue.Slight activity was demonstrable with 5- and 5-androstans as substrates in liver and the diformazan deposition was presumably due to the action of a steroid reductase.     

Histochemical localization of some hydroxysteroid dehydrogenases in the mouse epididymis.

The mouse epididymis was studied to localize histochemically a number of hydroxysteroid dehydrogenases in the various zones. The epithelium of the posterior half of the initial segment (head) and the anterior half of the middle segment (body) shows a strong reaction for delta5-3beta-, 3alpha,5alpha-, 3alpha,5beta-, 11beta, 16alpha-, 17beta, 20alpha-hydroxysteroid dehydrogenases. This activity attenuates posteriorly. Only the 11beta-hydroxysteroid dehydrogenase is present throughout the length of the epididymis. The luminal contents of the middle segment also show the histochemical utilization of a number of steroids.     

Cryopreservation of developing teeth

By using a slow rate of cooling, successful storage of developing teeth has been performed in liquid nitrogen. Dye exclusion tests indicate that 78 ± 8% of cells remain viable and transplantation to isologous hosts demonstrates that 86% of the stored developing teeth commence to grow and produce normal dental hard and soft tissue elements. The length of storage at −196 °C, for periods up to 3 months, appears to have no detrimental effect upon subsequent survival and development of tooth germs.     

Phosphoglucose isomerase in developing teeth

Summary The distribution of phosphoglucose isomerase in developing teeth of rats, using an indirect tetrazolium technique, is described. The demonstration of this enzyme, which occupies a position of considerable importance in carbohydrate metabolism, provides additional information regarding the biochemistry of odontogenic cells.     

Histochemical demonstration of some dehydrogenases and NAD-H diaphorase in cat Pacinian Corpuscles

Summary Using histochemical methods for G-6-P-DH, NAD-HD, M-DH, S-DH, L-DH and G-DH the author has examined the participation and distribution of these enzymes in Pacinian Corpuscles of male cats. The reactions for G-6-P-DH, L-DH, M-DH and NAD-HD show similarity regarding the intensity and the character of intrareceptoral distribution. The nerve fibre and its ending show the highest activity. Three other zones might be differentiated round them. The first zone situated in close proximity to the axon coincides with the inner core of the Corpuscles and shows higher activity than the others (second and third zones). The activity of the latter ones diminishes towards the periphery of the receptor.The reaction for S-DH is strongly expressed at the nerve fibre and its ending and weaker at the inner core of the Corpuscles.The reaction for G-DH is moderately expressed in the inner core whereas the nerve fibre and the outer core show the feeble activity.The author discusses the obtained results in relation to the necessity of energy and the ways it is obtained for the excitation of the axonal membrane.     

Plagiorchis elegans: Histochemical localization of dehydrogenases in the cercarial stage

Cercariae of Plagiorchis elegans Rudolphi 1802 collected from experimentally infected snails, Lymnaea palustris, were subjected to various histochemical tests for dehydrogenase systems. A high degree of activity was demonstrated for succinic dehydrogenase (EC 1.3.99.1), malic dehydrogenase (EC 1.1.1.37), isocitric dehydrogenase (EC 1.1.1.41), α-glycerophosphate dehydrogenase (EC 1.1.1.8), and glucose 6-phosphate dehydrogenase (EC 1.1.1.49). These enzymes were present in the tegument, tail, caudal pocket, excretory bladder, acetabulum, and oral sucker, particularly in the muscles around the stylet. Only moderate activity was obtained for lactic dehydrogenase (EC 1.1.1.27) and 6-phosphogluconate dehydrogenase (EC 1.1.1.44) at these sites, glutamic dehydrogenase (EC 1.4.1.2) was localized only in the tails of the cercariae and tests for alcohol dehydrogenase (EC 1.1.1.1) were completely negative. The cerebral ganglia and its commissures stained intensely in the tests for succinic, isocitric, α-glycerophosphate, and glucose 6-phosphate dehydrogenase systems. The results indicate the possibility that several energy-producing sequences may be available to these cercariae.