An unusual sexually dimorphic mosaic distribution of a subset of kallikreins in the granular convoluted tubule of the mouse submandibular gland detected by an antibody with restricted immunoreactivity

The granular convoluted tubule of the mouse submandibular gland contains a wide variety of biologically active proteins, including several kallikreins . The tubule is under multihormonal regulation, and is sexually dimorphic, being larger in males than in females. Correspondingly, levels of its vario us protein secretory products are more abundant in males than in females. H owever, isoelectric focussing studies show that the true tissue kallikrein, mK1, is more abundant in the female than in the male submandibular gland. In this study, an antiserum was prepared with restricted immunoreactivity f or mouse mK1, and possibly other kallikrein family members of low abundance in the mouse submandibular gland, and used for the immunocytochemical stai ning of the granular convoluted tubule cells in the submandibular gland of adult male and female mice, by indirect enzyme-labeled and immunogold-label ed antibody methods for light and electron microscopy, respectively. The di stribution of immunoreactive tubule cells showed an unusual sexual dimorphi sm. In males only a few scattered slender tubule cells were strongly staine d, while the more typical large tubule cells were only occasionally weakly positive, and many of them were not stained. By contrast, in females slende r tubule cells were not seen, and about two thirds of the more typical tubu le cells showed moderate to strong immunostaining. Immunoelectron microscop y revealed that immunostaining was confined to the secretion granules in gr anular convoluted tubule cells in both sexes. The slender tubule cells of m ales had many strongly stained small apical secretion granules and occasion al basal infoldings; in the weakly positive larger more typical tubule cell s not all secretion granules were positive, and there was intergranular var iation in the intensity of staining of positive granules. In females, altho ugh more tubule cells were stained, intergranular variations in staining in tensity were also noted. In both sexes, many tubule cells did not contain a ny secretion granules that showed immunogold labeling for kallikreins. Thes e findings establish that, in contrast to the situation for the majority of granular convoluted tubules proteins, mK1 and possibly other minor kallikr ein family members are more abundant in the granular convoluted tubules of female mice, and that there is considerable variation in the content of the se kallikreins not only between different tubule cells, but also in individ ual secretion granules in any given tubule cell in either sex.The granular convoluted tubule of the mouse submandibular gland contains a wide variety of biologically active proteins, including several kallikreins. The tubule is under multihormonal regulation, and is sexually dimorphic, being larger in males than in females. Correspondingly, levels of its various protein se cretory products are more abundant in males than in females. However, isoel ectric focussing studies show that the true tissue kallikrein, mK1, is more abundant in the female than in the male submandibular gland. In this study , an antiserum was prepared with restricted immunoreactivity for mouse mK1, and possibly other kallikrein family members of low abundance in the mouse submandibular gland, and used for the immunocytochemical staining of the g ranular convoluted tubule cells in the submandibular gland of adult male an d female mice, by indirect enzyme-labeled and immunogold-labeled antibody m ethods for light and electron microscopy, respectively. The distribution of immunoreactive tubule cells showed an unusual sexual dimorphism. In males only a few scattered slender tubule cells were strongly stained, w hile the more typical large tubule cells were only occasionally weakly posi tive, and many of them were not stained. By contrast, in females slender tu bule cells were not seen, and about two thirds of the more typical tubule c ells showed moderate to strong immunostaining. Immunoelectron microscopy re vealed that immunostaining was confined to the secretion granules in granul ar convoluted tubule cells in both sexes. The slender tubule cells of males had many strongly stained small apical secretion granules and occasional b asal infoldings; in the weakly positive larger more typical tubule cells no t all secretion granules were positive, and there was intergranular variati on in the intensity of staining of positive granules. In females, although more tubule cells were stained, intergranular variations in staining intens ity were also noted. In both sexes, many tubule cells did not contain any s ecretion granules that showed immunogold labeling for kallikreins. These fi ndings establish that, in contrast to the situation for the majority of gra nular convoluted tubules proteins, mK1 and possibly other minor kallikrein family members are more abundant in the granular convoluted tubules of fema le mice, and that there is considerable variation in the content of these k allikreins not only between different tubule cells, but also in individual secretion granules in any given tubule cell in either sex.