Fine structure of differentiating ameloblasts in the kitten

The fine structure of differentiating ameloblasts was studied in the lower second molar of 1-week-old kittens after perfusion fixation with and without subsequent decalcification. The differentiation zone was divided into three phases. In Differentiation 1, ameloblasts are about 27 μm long and face an uninterrupted basal lamina. The predentin adjacent to the basal lamina contains a few collagen fibrils oriented mainly at right angles to the ameloblast surface. This specialized predentin forms a well-defined layer, up to 1.5 μm thick, referred to as the junctional layer. In Differentiation 2, ameloblast processes extend through the basal lamina and the thickness of the junctional layer. The processes consist of cytoplasmic sheets forming a honeycomb-like network. Dentin starts to calcify after process-formation is underway. Two distinct types of odontoblast processes, having different shapes and contents, come in contact with the ameloblasts and push into the ameloblastic layer. In Differentiation 3, stippled material appears in the extracellular spaces between ameloblasts. Later, stippled material-like substances appear in the predentin close to the ameloblast apex and close to odontoblast processes within the dentin. Ameloblasts now are up to 40 μm high. Enamel secretion starts in small circumscribed areas which gradually enlarge, leading to the disappearance of the ameloblast processes. These findings are compared with results obtained in other species, including man, and their possible functional significance is discussed.     

Regeneration of acini in submandibular gland autografts

Regeneration of submandibular gland (SMG) secretory parenchyma is remarkably impaired in salivary gland diseases and under experimental conditions such as in tissue culture and after isografting. In our study acinar regeneration was found to depend on the site where the SMG tissue was implanted. Implantation of several 2-3 mm3 fragments of SMG subcutaneously in the back of the same donor adult male rat resulted in initial necrosis and mononuclear cell infiltration of the autograft. Then there was epithelial proliferation with the appearance within 28 days of lobules which contained numerous duct-like structures and only a few or no acini. In contrast, implanting SMG fragments in the anatomical bed of the donor gland resulted in the appearance of a more differentiated autograft. Although the initial tissue changes were similar to those seen in the autografts in the subcutaneous tissues of the back, the SMG autograft in the neck also contained numerous acini by 42 and 56 days after implantation. These data support the view that the implantation site influences the course of cytodifferentiation in SMG autografts.     

Fine structure of oncocytes in human salivary glands

Summary Oncocytes, cells displaying marked cytoplasmic acidophilia and granularity, are present in the acini and ducts of normal human salivary glands. These cells apparently originate by a process of sequential transformation of normal epithelial cells. In the early forms, there is a great increase in the number of mitochondria, which are typical in morphology. In later oncocytes, these organelles undergo striking changes in form and size. These mitochondrial changes are accompanied by the gradual disappearance from the oncocyte of other cytoplasmic membrane systems and of plasmalemmar specializations. It is suggested that the structurally modified mitochondria are biochemically deficient.

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Die Feinstruktur der Onkocyten in Speicheldrüsen der Menschen

Zusammenfassung Onkocyten finden sich sowohl in den Acini wie in den Ausführungsgängen normaler Speicheldrüsen. Sie besitzen ein eosinophil granuliertes Cytoplasma und sind wahrscheinlich Abkömmlinge normaler Drüsenzellen, aus denen sie sich über eine Reihe von Zwischenstufen entwickeln. Die Frühformen zeigen eine starke Zunahme der Mitochondrien. In den späten Stadien erfahren die Mitochondrien charakteristische Veränderungen in bezug auf Form und Größe, begleitet von einem Schwund der cytoplasmatischen Membransysteme und weiterer plasmacellulärer Spezialorganellen. Die geschädigten Mitochondrien dürften auch in ihrer biochemischen Leistung beeinträchtigt sein.

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The author acknowledges the expert technical assistance of Mr.Roy R. keppie and Mrs.Mona Brandreth.

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This work was supported in part by grants from the Max C. Fleischmann Foundation of Nevada and the Henry Spenadel Trust, and by N. C. I. grant CA 08748.     

糖尿病大鼠下颌下腺内肥大细胞的形态学观察

目的观察糖尿病大鼠下颌下腺内肥大细胞形态和数量变化。方法SD雄性大鼠30只,随机分为实验组12只(4周、12周各6只)、治疗组12只(4周、12周各6只)及对照组6只,用链脲佐菌素复制糖尿病动物模型,应用HE和甲苯胺蓝(Toluidineblue,TB)染色观察并记数肥大细胞。结果对照组大鼠下颌下腺内肥大细胞呈圆形。卵圆形及不规则形,细胞内颗粒密集,平均肥大细胞数为(6.55±4.02)个/HP。实验组大部分肥大细胞胞内颗粒稀疏,有脱颗粒现象。4周平均肥大细胞数为(15.44±5.92)个/HP,12周为(46.67±7.78)个/HP,差异有统计学意义(P<0.01),而治疗组肥大细胞形态结构与对照组比较无明显区别,4周平均肥大细胞数为(12.33±1.67)个/HP,12周为(21.71±6.25)个/HP。结论糖尿病可导致下颌下腺内肥大细胞脱颗粒活跃、数量增多,提示肥大细胞可能参与糖尿病发生与发展病理过程。     

甲状腺功能减退症大鼠下颌下腺形态学及超微结构的改变

目的:观察甲状腺功能减退症(甲减)大鼠下颌下腺形态学及超微结构的变化。方法:将成年SD大鼠随机分为对照组、甲减组、甲状腺素治疗组。成模后,称重,取血检测三碘甲状腺激素(T_3)、甲状腺素(T_4)、促甲状腺素(TSH);取下颌下腺组织,H-E染色及电镜观察。结果:造模后对照组、甲减组、甲状腺素治疗组体质量分别为(444.50±19.42)g、(292.25±17.40)g、(340.50±27.65)g,后两组与对照组比较、后两组间比较差异均有统计学意义。对照组、甲状腺素治疗组与甲减组T_3、T_4、TSH比较均有统计学意义。甲减组下颌下腺腺泡萎缩,排列不规则,颗粒曲管数目减少,直径变小,胞质淡染;甲状腺素治疗组明显好转。甲减组腺细胞核固缩、染色质致密,线粒体空泡变性,粗面内质网扩张,核糖体脱颗粒。甲状腺素治疗组少数细胞有核固缩现象,线粒体少量空泡变,粗面内质网轻度扩张,没有明显的核糖体脱颗粒现象。结论:甲减可引起下颌下腺形态学及超微结构异常,甲状腺素治疗有效,推测甲减的病理生理机制可影响下颌下腺的形态结构。     

糖尿病大鼠下颌下腺内水通道蛋白-3和-8的表达变化及意义

目的观察水通道蛋白-3(AQP3)和水通道蛋白-8(AQP8)在糖尿病大鼠下颌下腺内表达变化。方法 SD大鼠随机分为对照组、糖尿病组和治疗组,每组10只;糖尿病组和治疗组大鼠腹腔注射2%链尿佐菌素(35 mg/kg)复制Ⅱ型糖尿病模型,治疗组予以胰岛素(3u/d)处理;8周后,取下颌下腺,分别进行HE和免疫组织化学染色。结果与对照组比较,糖尿病组下颌下腺腺泡轻度萎缩,细胞排列紊乱,导管数目减少,直径变小。AQP3表达在三组间无明显差异;与对照组比较,糖尿病组AQP8表达下降,治疗组AQP8表达较糖尿病组有所上调。结论糖尿病大鼠下颌下腺内AQP8低表达可能与糖尿病患者口渴的发病机制相关。     

糖尿病大鼠下颌下腺内水通道蛋白-1和5表达变化及意义

目的:观察水通道蛋白-1(AQP1)和水通道蛋白-5(AQP5)在糖尿病大鼠下颌下腺内表达变化,探讨糖尿病患者口渴症状的发生机制.方法:SD大鼠随机分为对照组、糖尿病组、治疗组.取大鼠下颌下腺,分别进行H-E染色、免疫组织化学显色(SP法)和计算机图像分析.结果:对照组和治疗组的血糖分别与糖尿病组血糖比较,均有差异;与...     

Fine structure of excretory ducts of human salivary glands

Excretory ducts of human major salivary glands are lined by an epithelium consisting of principal cells and by a discontinuous row of basal cells. The principal cells are tall and columnar with mitochondria, large lipofuscin granules and a central nucleus. Just beneath the plasmalemma bordering the lumen, their cytoplasm contains a number of small granules and vesicles similar to those observed in cells of striated ducts. Both in TEM and SEM, these cells also show large apical protrusions devoid of cytoplasmic organelles that may represent a kind of apocrine secretion. The cytoarchitecture of the principal cells seems to be at variance with that of cells of striated ducts. First, the cell body remains unique and does not split into major basal processes. Second, these cells usually lack the long laminated basal folds, housing vertically aligned mitochondria, that are typical of striated ducts. Instead, below the smooth area occupied by the junctional complexes, the lateral cell surfaces are completely covered by a great number of short irregular processes. These organelle-free folds are apparently involved in the mechanism of ion transport since, at their level, there is a strong reactivity for the transporting enzyme K(+)-pNPPase. The basal cells, which are small and cuboidal, have a dense and filamentous cytoplasm. Their functional role is still uncertain.     

Mouse uterine glands during the peri-implantation period: Fine structure

Mouse uterine glands, obtained during the peri-implantation period of pregnancy, were investigated using light and electron microscopy. From day 4 to day 6 of pregnancy, there was a progressive luminal dilation and an accumulation of dense homogeneous material in the gland lumina. Although numerous large electron-lucent vesicles were present in the apical portion of the glandular cells on day 4, their number decreased by days 5 and 6 of pregnancy. Dense granules were present along the apical border of many glandular cells on day 6. In addition, there was an increase in the number and more orderly arrangement of RER cisternae by day 6 of pregnancy. Cytochemical studies on days 4, 5, and 6 of pregnancy, using the periodic acid-thiocarbohydrazide-silver proteinate method for the ultrastructural localization of carbohydrate material, showed specific staining of the multivesicular bodies and the saccules of the concave surface of the Golgi complex, but not the dilated saccules of the convex surface. Specific staining was also observed over both the luminal material and apical granules present on day 6 of pregnancy. The cytochemical evidence suggests that the secretory product of the uterine glands has carbohydrate components and that carbohydrate material accumulates in the Golgi complex. In addition, the morphological changes observed imply increased secretory activity of the uterine glands during the peri-implantation period. Thus, the uterine glands must be considered an important source of uterine fluid components during the peri-implantation period.     

Isolation of acini from nasal glands of the guinea-pig

A procedure for isolating the acinar cells of the serous gland in the mammalian nasal septum has been developed. This technique is characterized by meticulous and selective isolation with minimal contamination by the surface epithelial cells and employs enzymatic treatment with collagenase. The isolated cells were confirmed to be serous gland acini as shown by negative staining with Alcian blue and a high electron density of the granules. The acini were more than 90% viable as judged by trypan blue exclusion. Ultrastructural integrity of the cells was well maintained following the isolation procedure. Application of acetylcholine to the isolated acini induced an inward current in a whole-cell patch clamp and increased intracellular Ca²⁺ concentration measured by fura-2. These acetylcholine responses were completely blocked by atropine. These physiological findings directly demonstrated that nasal gland acini possess muscarinic-activated receptors as previously suggested. These isolated cells hold promise for the in vitro study of secretory mechanisms in the mammalian nasal gland.     

大鼠下颌下腺内自分泌运动因子及其受体的定位

目的:探讨自分泌运动因子及其受体在大鼠下颌下腺中的表达特点,为进一步研究自分泌运动因子及其受体对下颌下腺是否有功能意义提供依据。方法:应用HE和免疫组织化学SABC法染色。结果:大鼠下颌下腺颗粒曲管、纹状管及小叶间导管上皮细胞呈自分泌运动因子及其受体免疫反应阳性。免疫反应产物分布于胞质,胞核为免疫反应阴性。下颌下腺的腺泡上皮细胞均呈自分泌运动因子及其受体免疫反应阴性。结论:正常大鼠下颌下腺仅导管上皮有自分泌运动因子及其受体的分布,提示下颌下腺产生的自分泌运动因子对下颌下腺及机体可能有重要调节意义。     

Radioprotective effect of heat shock protein 25 on submandibular glands of rats

Irradiation (IR) is a fundamental treatment modality for head and neck malignancies. However, a significant drawback of IR treatment is irreversible damage of salivary gland in the IR field. In the present study, we investigated whether heat shock protein (HSP) 25 could be used as a radioprotective molecule for radiation-induced salivary gland damage in rats. HSP25 as well as inducible HSP70 (HSP70i) that were delivered to the salivary gland via an adenoviral vector significantly ameliorated radiation-induced salivary fluid loss. Radiation-induced apoptosis, caspase-3 activation, and poly(ADP-ribose) polymerase cleavage in acinar cells, granular convoluted cells, and intercalated ductal cells were also inhibited by HSP25 or HSP70i transfer. The alteration of salivary contents, including amylase, protein, Ca+, Cl-, and Na+, was also attenuated by HSP25 transfer. Histological analysis revealed almost no radiation-induced damage in salivary gland when HSP25 was transferred. Aquaporin 5 expression in salivary gland was inhibited by radiation; and HSP25 transfer to salivary gland prevented this alteration. The protective effect of HSP70i on radiation-induced salivary gland damage was less or delayed than that of HSP25. These results indicate that HSP25 is a good candidate molecule to protect salivary gland from the toxicity of IR.     

Effect of estradiol on ultrastructure of granular ducts in submandibular glands of female rats

The effects of estradiol on the granular ducts in submandibular glands of female albino rats were studied. Twenty-five-milligram pellets of 17 beta-estradiol were implanted subcutaneously in the experimental animals, and their glands, as well as controls, were examined after 2, 4, 7, and 10 wk using light and electron microscopy. During the course of the experiment an increasing proportion of the granules in the granular ducts appeared more lightly stained in the experimental animals. In the estradiol-treated rats the granular ducts increased in relative cross-sectional area at a faster rate than in the controls, which exhibited maturation changes. In addition, the average number of granules per granular duct cell decreased significantly in the treated animals. Our results indicate that estradiol caused a change in the cytology of the granular ducts suggesting an alteration in protein synthesis. These results might occur through a change in structural proteins or in other hormones and growth factors which are known to influence the submandibular gland.     

The fine structure of secretory granules in submandibular glands of the rat during early postnatal development

The secretory end-pieces of the submandibular gland of rats during the first week of postnatal development are studied with regard to the fine structure of the secretion granules in these end-pieces. The terminal ends of the secretory ducts during this period consist of two types of cells; one cell is an acinar-type and the other is a duct-type found in the gland of adult rats. The secretion granules of the acinar-type cells are similar in appearance to those of the acinar cells in the gland of adult rats, and the structure of these granules remains the same throughout the week. However, granules widely different in appearance are present in the duct-type cells, and their structure varies in different cells as well as within a single cell at different stages of development. These granules contain unusual substructures which are not found in the secretion granules of adult rats, suggesting that the granules are transitory. Granules containing short tubular profiles are predominant in the gland of one day-old rats. A large number of granules in three day-old rats contain elongated tubules. More granules of widely different substructures are present in the gland of seven day-old rats than in the gland of younger rats. The matrix of the granules in seven day-old rats is of higher density than that of the granules in younger rats. In the dense matrix of these granules, less dense tubules form fingerprint-like or somewhat more irregular patterns.