Mieko Sashima

Harderianization is another sexual dimorphism of rat exorbital lacrimal gland.

The exorbital lacrimal glands (ELG) of rats were examined for both sexes to determine what degree of harderianization occurred as a function of age and after castration, and to investigate its time course and origin in ELG. Light microscopically, very small Harderian foci were seen in the ELG of both sexes at 3 weeks of age. As the male rats became older, the relative volume of the Harderian gland (HG) cells in the ELG increased. At age 6 months, the value was 1.25 +/- 0.31% in males and 0.13 +/- 0.05% in females (p less than 0.05). After castration, a significant decrease (0.21 +/- 0.01%, p less than 0.05) was observed in that of male ELG. In contrast, in female ELG, HG cells were inconspicuous and the relative volume of those did not vary during this experimental period or after castration. It appeared that the HG cells had developed from undifferentiated basal cells of the acini and the intercalated ducts in the ELG at age 2-6 months. Then, at age 22 months, they also probably developed from those of the excretory ducts of the ELG.

A sexual dimorphism of mucous cells in the submandibular salivary gland of rat

Submandibular glands of both sexes from one week to six months-old were serially sectioned, and mucous cells showing a strong positive stain to alcian blue pH 2.5, first detected at two weeks, showed a high degree of inter-sectional and inter-individual variability. In males, the percentage of animals having mucous cells increased with sexual maturation and attained 100 per cent at age six months. In females, the maximum (60 per cent) was reached by four weeks and then decreased with sexual maturation. Only 28.5 per cent of the glands of adult female rats contained mucous cells. In the six-month-old females, the percentage of female rats having mucous cells increased three-fold after injection of testosterone (total dose 17-21 mg; p less than 0.05, Fisher test). Mucous cells in testosterone-injected females displayed morphological features which suggest a transition from original seromucous cells to mucous cells.

Alveolar Bone Loss of Senescence-accelerated Mouse (SAM)

SAM-R/1/Iw (senescence-accelerated mouse, resistant) and Pl2/Iw (senescence-accelerated mouse, prone) under a conventional environment and eating standard pellets were examined for alveolar bone loss and the presence of periodontitis around maxillary and mandibular molars as a function of age. Neither SAM strain manifested a chronic periodontitis similar to that in humans, and no obvious plaque and calculus were observed. However, in both strains, 15% of M3 was lost after 13 months of age, and alveolar bone loss gradually increased with advancing age. Though there was no significant difference in the incidence of M3 loss between the two strains, P/2/Iw showed a higher alveolar bone loss around all molars than did Rl1/ Iw after one month of age throughout their life span. For Ml, the difference in alveolar bone loss between Pl2/Iw and Rl1/Iw was significant, and it was probably caused by the difference in degree of molar eruption. Other factors, such as occlusal trauma and gingivitis, may play some role in alveolar bone loss.

Glucocorticoid-induced growth inhibition with enhanced expression of ductal epithelium of human salivary gland adenocarcinoma cells transplanted into athymic nude mice.

The effect of glucocorticoid on growth and the histologic features of adenocarcinoma induced in nude mouse by the inoculation of neoplastic epithelial cells of salivary duct origin (HSG) were studied. Subcutaneous injection of dexamethasone (low‐dose group: 0.05 μg/g, high‐dose group: 0.25 μg/g) four times a week for 8 weeks significantly (P < 0.05) inhibited tumor growth, and in one mouse the tumor had almost completely disappeared by the middle of the sixth week of treatment. In addition, dexamethasone induced an apparent luminal structure in the tissue section of the tumor and enhanced the immunoperoxidase reaction to epithelial membrane antigen. The results indicate that dexamethasone inhibited the proliferation of HSG cells in the nude mouse transplantation system probably by inducing the cellular differentiation of the HSG cells toward the more differentiated ductal epithelia via glucocorticoid receptors.

Age-related changes of the granular intercalated duct cells of male rat submandibular gland.

The granular intercalated duct (GID) cells showed a progressive increase in number from two to four months of age (p less than 0.01). Their secretory granules also increased in number. Among all the age groups (2-22 months), the number of the GID cells in submandibular gland was highest of six months; they were then also most conspicuous with many electron-dense secretory granules in the cytoplasm. From 12 to 22 months, they showed regressive changes such as a decrease in cell number and in the number of secretory granules. The significance of these age-related changes of the GID cells is unknown.

Immunohistochemical detection of ras 21 in oral squamous cell carcinomas

The expression of the ras p21 in oral squamous cell carcinoma was examined immunohistochemically with the use of a monoclonal antibody NCC-RAS-001 with the avidin-biotin-peroxidase complex method. The expression of ras p21 product was detected in 65.7% (44 of 67 cases) of cancer patients. On the basis of the degree of histologic differentiation of the cancer cells, the incidence of ras p21 was found to be as follows: 63.4% (26 of 41 cases) were well differentiated; 86.7% (13 of 15 cases) were moderately differentiated; and 45.5% (5 of 11 cases) were poorly differentiated. The highest incidence was found in patients in their sixties--80.0% (16 of 20 cases). The incidence decreased to 40% in patients over 80 years of age. The incidence of ras p21 on the basis of location was as follows: 81.8% (9 of 11 cases) involved the buccal region, 70.6% (12 of 17 cases) were in the gingiva, and 55.0% (11 of 20 cases) were in the tongue.

Age-related Development of the Long-junctional Epithelium in the Senescence-accelerated Mouse

The mesial gingiva of the maxillary first molar of SAM-R/1/Iw (senescence-accelerated mouse, resistant/1/Iwate) and the P/2/Iw (prone/2/Iwate) were studied morphologically by quantitative and qualitative methods as a function of age (one-, two-, six-, 12-, and 16-month-old). In this region, neither plaque nor periodontitis has been found (Sashima et al., 1990a). Statistical analyses of the gingival tissues in this region in both strains showed that, with age, the length of the junctional epithelium (JED) increased, the depth of the gingival sulcus (GSD) did not change, and the height of the gingival crest (GCD) decreased. Therefore, long-junctional epithelium developed, and gingival recession occurred, since a periodontal pocket did not develop with age in either strain. In particular, there was a strong correlation between the JED and age in both strains (r = 0.84, p < 0.05 for the R/l/Iw, and r = 0.92, p < 0.05 for the P/2/ Iw). The JED, GSD, and GCD of the P/2/Iw were higher than each of those in the R/l/Iw after six months of age; however, there were no significant differences between the R/l/Iw and the P/2/Iw for any age group (one-, two-, six-, 12-, and 16-month-old).

Age-related changes in the d-aspartic acid content of the teeth of the senescence-accelerated mouse

It is known that D-aspartic acid increases with age in dentine. Here, age-related changes in the D to L-aspartic acid (D/L) ratios of the lower teeth of two different sublines of the senescence-accelerated mouse (SAM), SAMP2/Iw (SAM, prone 2/Iwate) and SAMR1/Iw (SAM, resistant 1/Iwate) were measured by gas chromatography. The D/L ratio of the molars increased with advancing age, whereas that of the incisors did not. In mice younger than 6 months of age the D/L ratio of the molars from SAMP2/Iw tended to be higher than that from SAMR1/Iw, whereas the converse applied to older mice. Racemization in the molars occurred significantly faster in SAMR1/Iw than SAMP2/Iw (p = 0.01-0.001). Analysis according to the kind of tooth showed that the D/L ratio increased gradually in the order incisors < third molars < second molars < first molars, indicating that the ratio was higher the earlier the molars formed. As racemization depends upon the environmental temperature, the rectal temperatures of the mice were also examined. The rectal temperature of SAMP2/Iw was highest when they were 2 months old, but declined rapidly thereafter, whereas the rectal temperature of SAMRI/Iw was highest when they were 6 months old, after which it declined gradually. These results indicate that the D-aspartic acid contents of the molars of SAMR1/Iw and SAMP2/Iw increase with age in a different fashion and suggest that the fashion was determined by the body temperature, but not by the senescence-accelerated age.