Moreira J E, Ball W D, Mirels L, Hand A R
Clinical Investigations and Patient Care Branch, National Institute of Dental Research, National Institutes of Health, Bethesda, Maryland 20892.
Am J Anat. 1991 Jun;191(2):167-84. doi: 10.1002/aja.1001910204.
The seromucous acinar cells of the adult rat submandibular gland secrete a characteristic mucin glycoprotein and a family of unusual glutamine/glutamic acid-rich proteins (GRP). Monoclonal antibodies to the mucin and GRP localized in a very few Type III cells in glands of newborn and 1 day-old rats, using light and electron microscopic immunocytochemistry. Both mucin and GRP reactivities were present in the polymorphic Type IIIP granules during the 1st postnatal week. By 9 days after birth, the granules contained both mucin and GRP and were mucous-like in appearance. At earlier stages, however, cells containing only GRP or mucin could be found, indicating that the initiation of GRP and mucin biosynthesis may not be coordinately regulated. No reactivity was seen in the neonatal Type I cells or in duct cells at any age. Northern and Western blot analysis showed GRP mRNA and protein levels to be barely detectable at birth, with marked increases during the first 2 postnatal weeks. In contrast, Western blots of B1-immunoreactive proteins (B1-IP) showed levels highest in the 1st week and markedly decreased in the adult. Immunocytochemical colocalization, using gold particles of different sizes, showed that the B1-IP, mucin, and GRP colocalized in the granules. These results strengthen the hypothesis that the adult acinar cells develop from the neonatal Type III cells. No evidence was obtained for the involvement of Type I cells in the pathway of acinar cell development.
成年大鼠下颌下腺的浆液黏液性腺泡细胞分泌一种特征性黏蛋白糖蛋白和一族富含谷氨酰胺/谷氨酸的特殊蛋白质（GRP）。利用光镜和电镜免疫细胞化学技术，针对黏蛋白和GRP的单克隆抗体定位于新生大鼠和1日龄大鼠腺体中极少数的III型细胞。出生后第1周，多形性IIIP型颗粒中同时存在黏蛋白和GRP反应性。到出生后9天，颗粒中同时含有黏蛋白和GRP，外观呈黏液样。然而，在早期阶段，可以发现仅含有GRP或黏蛋白的细胞，这表明GRP和黏蛋白生物合成的起始可能未受到协同调节。在新生I型细胞或任何年龄段的导管细胞中均未观察到反应性。Northern印迹和Western印迹分析显示，GRP mRNA和蛋白水平在出生时几乎检测不到，在出生后的前2周显著增加。相比之下，B1免疫反应性蛋白（B1-IP）的Western印迹显示其水平在第1周最高，在成年时明显降低。使用不同大小的金颗粒进行免疫细胞化学共定位显示，B1-IP、黏蛋白和GRP在颗粒中共定位。这些结果强化了成年腺泡细胞由新生III型细胞发育而来的假说。未获得I型细胞参与腺泡细胞发育途径的证据。
