Julia Meyer

Characteristics of a Proteolytic Enzyme in the Submaxillary and Sublingual Glands of the Albino Rat

SALIVARY glands have long been known to produce amylase and mucin. Saliva, on the other hand, has been known to contain mucin and amylase, and also to show some proteolytic activity.5 Protease activity of the salivary glands had not been demonstrated until Junqueira, Fajer, Rabinovitch, and Frankenthal2 showed that extracts of the submaxillary glands of mice could degrade casein. A preliminary study showed that the submaxillary gland of the rat also had proteolytic activity. The present investigation is concerned with the characteristics of this enzyme system.

Age-related changes in the epithelial dimensions and capillaries of the oral mucosa of the rat.

Seven homologous regions of the oral mucosa were compared in rats 6, 18 and 30 months of age. Capillaries were visualized by their alkaline-phosphatase activity revealed by an azo-dye. Measurements on tracings of densely-spaced histological sections in two planes perpendicular to the epithelial surface showed epithelial thickness in masticatory mucosa decreased by 18 months, but increased by 30 months. In regions of lining mucosa, thickness increased by 18 months, but decreased by up to 13 per cent at 30 months. The size of the capillary bed increased substantially by 18 months and further increased by 30 months. Variability in the epithelial dimensions increased up to 18 months but not beyond; variability in the capillary measurements showed no change with age. The quantitative relationship between epithelial thickness and the size of the epithelial-connective tissue interface and the capillary bed remained unchanged with age.

Effects of zinc deficiency on developmental changes in alkaline phosphatase and carbonic anhydrase activities in the submandibular gland of the rat.

Abstract The alkaline phosphatase (AP) and carbonic anhydrase (CA) activities were studied in male rats placed at weanling age on a diet containing 0.4 parts/10 6 of zinc for periods of 9, 18 and 27 days. Weight-matched pair-fed rats were kept on the same diet supplemented with 40 parts/10 6 of zinc. The body weight of controls showed a continuous increase; body weight of zinc-deficient animals remained unchanged. Zinc concentration in submandibular gland was the same in all groups of control and zinc-deficient animals. AP activity, chiefly localized in the myoepithelial cells, progressively increased in controls from day 9 to 27. AP activity in the zinc-deficient animals did not increase. It was lower than in controls even at 9 days and further decreased with prolonged zinc deficiency. CA activity, chiefly localized in cells of the duct system, rose with age in the controls at twice the rate of AP activity, a rise attributed to the steep rise in proportion of duct cells reported for this age span. By contrast, CA activity in the glands of zinc-deficient rats remained constant at all periods of deficiency, accounting for the increasing difference from controls with prolonged zinc deficiency. Failure of CA activity to rise with age in zinc-deficient rats is attributed to failing proliferation of duct cells, reflecting the inhibition of cell proliferation reported for many tissues of the zinc-deficient animals, a view supported by the maintenance of unchanged body weight over a 4-week-period. Inhibition studies using acetazolamide showed identical degress of inhibition in homogenates from control and deficient animals over a wide range of inhibitor concentrations. Rats fed for 9 days on the zinc-supplemented diet after 27 days on the deficient diet doubled their weight and showed AP and CA activities of the same level as controls that were pair-fed for 27 days and given unrestricted food for the last 9 days.

Metaplastic Keratinization in the Human Buccal Mucosa

Unlike the skin, which is keratinized everywhere, the human oral cavity contains keratinized and unkeratinized regions. The unkeratinized mucosa as seen in the cheek differed in many ways from the keratinized mucosa as seen in the hard palate.1 Some of the differences were obviously related to keratinization and some to regional adaptation. It was not clear whether other differing traits of the palatal mucosa are the necessary corollaries of the keratinizing process or the expression of regional differentiation. The present study is concerned with metaplastic keratinization as it occurs in the mucosa covering fibromas and fibrous hyperplasias of the cheek. Surgical specimens which happen to include unchanged buccal mucosa, and thus contain unkeratinized and keratinized mucosa from the same region, provide a material which avoids the uncertainty of regional differentiation and that of individual variation as well. The differences between unkeratinized and keratinized buccal mucosa were found to be the same as those between unkeratinized buccal and keratinized palatal mucosa. Consistent changes had occurred in the lamina propria; epithelial configuration; epithelial thickness; and in size, shape, and composition of the basal and other epithelial cells. These differences appear to be related to the keratinizing process and not to regional adaptation. Materials and Methods

Dry weight and size of cells in the buccal epithelium of zinc-deficient rats: A quantitative study

Abstract A diet containing 1.3 mg Zn/kg was given to male weanling rats for a 4-week-period. Controls were given the same diet supplemented by 40 mg Zn/kg. After death, dry weight per volume of buccal epithelium was determined for successive histologic layers by methods of ultra-micro-assay and the relative size of granular cells by a comparison of the numbers of cell nuclei in controls and experimental groups. The buccal epithelium of the experimental animals showed parakeratosis and increases in epithelial thickness and in the number of dividing cells. Dry weight per volume was elevated over that of controls beginning in the basal cells, and the size of granular cells was increased. The relative dry weight of granular cells in the experimental group, calculated from increase in dry weight per volume and increase in cell size, was nearly twice that in the control group. Since the rate of production of granular cells is nearly three times that of controls, increased synthetic activity and cell hypertrophy occurred in conjunction with accelerated cell proliferation. The effects of zinc deficiency are compared with those of other conditions of accelerated rates of cell proliferation.

Regional differences in gradients of dry residue density in oral epithelia of the rat: A quantitative study

Grams of dry weight per cm3 of tissue (DRD) were determined on the successive histologic layers of rat buccal and palatal mucosa, both of which form thick layers of orthokeratin. The experimental animals were six young adult male albinos of Simonsen strain. Microdissection was used for isolation of tissue fragments from frozendashdried sections, a quartz fibre balance (according to Lowry) for weighing and a split-image microscope for measuring the dimensions of the fragments. The density of basal cells in both tissues was 0.26g/cm3 and both showed a rise of 12 per cent between basal and lower spinous cells. Succeeding layers of the palate showed a continuous rise, those of cheek a continuous decline. The greatest change in both tissues occurred between granular and keratin layer. Palatal keratin had a density of 0.63g/cm3, buccal keratin of 0.21g/cm3. Sample variability was 9–12 per cent of the average per layer per animal and greatest in cheek keratin. Individual variability was 2–6 per cent of the average for six animals. Taking changes in cell size into account, it was concluded that loss of water occurs between granular and keratin layers of the palate, but uptake of water between deeper and superficial keratin cells of the cheek. Different regions of oral orthokeratin thus showed opposite responses to their common fluid environment.

A Simple Two-Dye Basic Stain Facilitating Recognition of Mitosis in Plastic Embedded Tissue Sections

Semithin sections of buccal and palatal mucosa fixed in 2.5% glutaraldehyde followed by 1% osmium and embedded in Durcupan (an araldite-based resin) were stained with 2% malachite green in 50% ethanol at 80 C and poststained in 0.05% crystal violet in Sorensens phosphate buffer (pH 6.4) at 45 C. Nuclear envelopes and chromatin stain vivid purple in contrast to the surrounding green cytoplasm and cell borders. Chromosomes of dividing cells stain bluish violet. Nucleoli, depending on their level in the epithelium, stain differing shades of greenish blue. The distinct and differential staining of each of these components facilitates recognition of mitoses in oral epithelium, where the small size and crowding of cells in the proliferative compartment renders more conventional stains for plastic sections inadequate.

Early effects of smoking on surface cytology of the oral mucosa: II. Cell changes in smokers☆

Abstract The frequencies of seventeen cell types in smears taken in clinically healthy areas of ten regions of the oral mucosa were compared in thirty-seven nonsmokers and forty-one heavy smokers. The subjects were men between 30 and 50 years of age. Smears were processed by the Papanicolaou technique, and 100 serial cells per smear were classified. Smoking was found to affect the frequency of almost all cell types in each of the ten regions. In nine of ten regions, smokers showed a shift toward less mature cell types. In three keratinized regions and in two regions with intermediate degrees of keratinization, the frequency of cells with orange cytoplasm decreased. In four nonkeratinized regions, the frequency of cells with pink cytoplasm decreased. Balancing increases in the keratinized regions occurred in the less mature cells with only partly orange but partly still pink cytoplasm, while in the non-keratinized regions the greatest increases were seen in the least mature of the cell types with blue cytoplasm. Thus, by contrast to the hyperkeratotic lesions clinically associated with the use of tobacco, the earliest effects of smoking, preceding clinical changes, are a shift from cells with higher degrees of keratinization to cells with lower degrees.

Age-related changes in capillaries of rat oral mucosa. A quantitative electron microscopic study.

Ultrastructural age changes in capillaries of the buccal mucosa were examined in montages of cross sections made from electron micrographs at 37,500 x. Six rats aged 6 months and 6 aged 30 months were perfused with glutaraldehyde and conventional thin sections obtained. Two capillaries located within a connective tissue papilla were studied from each rat. Capillaries of the old group differed from those of the young group by statistically significant increases in several parameters. The endothelial cell was increased in thickness, especially in the vicinity of junctions. The frequency of pinocytotic vesicles/unit length of the cell circumference was nearly doubled. Junctions were of nearly double length and took a more oblique course. All parts of the basement membranes were thickened, though perhaps less than seems true in skin. In striking contrast to epidermis, the epithelium of oral mucosa undergoes no appreciable thinning with age. We suggest that the observed age increases in frequency of pinocytotic vesicles and in the length of junctions may facilitate blood/tissue exchange, thus compensating for impaired exchange due to the thickened basement membranes. These compensatory changes in conjunction with the unchanged size of the mucosal capillary bed in the aged rat (demonstrated previously) could explain the unchanged thickness of the oral epithelium.

Frequency and distribution of binucleate cells in oral epithelium of several species of laboratory rodents

Keratinocytes in certain regions of rodent oral epithelium have a tendency to form a peculiar type of binucleate cell. The nuclei, in contrast to those in binucleate cells in most other tissues, are closely apposed with a flat interface, tetraploid and of approx. equal size. Binucleate cells were absent from the oral epithelium of several unrelated non-rodent mammalian species, but they occurred in descending order of frequency in guinea pig, rat, hamster and mouse; they were in epithelia of the lining mucosa, but absent from epithelia of the masticatory mucosa. In buccal epithelium of the rat, they constituted 2.5 per cent of the basal cells and 8.2 per cent of the lower spinous cells. This frequency was maintained in the succeeding cell layers. Regions of stimulated epithelium in zinc-deficient rats showed a four-fold increase over controls in frequency in the germinative cell layers and persistently higher frequency in succeeding layers, including in parakeratin. The mode of formation of the cells is unknown, but it was not associated with a lag in cytoplasmic division.