We examined morphological differences between the sublingual and submandibular glands with special reference to their innervation. The sublingual gland contained abundant periodic acid Schiff-positive mucous acini: some lobules were composed of purely mucous acini, while others were purely serous or mixed. However, in the submandibular gland, the area of mucous acini was very limited. Notably, in the sublingual gland, immunohistochemistry for neuron-specific enolase demonstrated that the serous acini carried a higher density of nerve elements than the mucous acini. However, no such difference was evident in the submandibular gland, possibly due to the small areas of the mucous acini. In both types of gland, neuronal nitric oxide synthase-positive parasympathetic nerves as well as tyrosine hydroxylase-positive sympathetic nerves were observed in the interlobular tissue, but we were unable to trace these thin fibers to the acini. Myoepithelial cells expressed smooth muscle actin, but were negative for S100B protein, glial fibrillary acidic protein and neuron-specific enolase. However, antibody against S100A stained some of the myoepithelial cells and ductal cells in the sublingual gland. Cells positive for peripheral myelin protein 22 were seen in some of the ductal cells in the submandibular gland, but not in the sublingual gland. Therefore, with regard to the neurogenic features of the gland cells, S100B reactivity might disappear first in postnatal life, whereas S100A reactivity is likely to remain as aging progresses. The sublingual gland in elderly individuals seems to provide a good model for comparison of the nerve supply between mucous and serous acini.
Actins ; Aged* ; Aging ; Cadaver* ; Glial Fibrillary Acidic Protein ; Humans ; Immunohistochemistry ; Muscle, Smooth ; Myelin Sheath ; Neurons ; Nitric Oxide ; Periodic Acid ; Phosphopyruvate Hydratase ; Sublingual Gland* ; Submandibular Gland ; Tyrosine

In the developing human musculoskeletal system, cell death with macrophage accumulation occurs in the thigh muscle and interdigital area. To comprehensively clarify the distribution of macrophages, we immunohistochemically examined 16 pairs of upper and lower extremities without the hip joint (left and right sides) obtained from 8 human fetuses at approximately 10-15 weeks of gestation. Rather than in muscles, CD68-positive macrophages were densely distributed in loose connective tissues of the flexor aspects of the extremities, especially in the wrist, hand and foot. In contrast, no or fewer macrophages were evident in the shoulder and the extensor aspects of the extremities. The macrophages were not concentrated at the enthesis of the tendon and ligament, but tended to be arranged along other connective tissue fibers. Deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling revealed apoptosis in the hand lumbricalis muscles, but not in the area of macrophage accumulation. Likewise, podoplanin-positive lymphatic vessels were not localized to areas of macrophage accumulation. Re-organization of the connective tissue along and around the flexor tendons of the hand and foot, such as development of the bursa or tendon sheath at 10-15 weeks, might require the phagocytotic function of macrophages, although details of the mechanism remain unknown.
Apoptosis ; Cell Death ; Connective Tissue ; Deoxyuracil Nucleotides ; Deoxyuridine ; Extremities ; Fetus ; Foot ; Hand ; Hip Joint ; Humans ; Ligaments ; Lower Extremity ; Lymphatic Vessels ; Macrophages ; Muscles ; Musculoskeletal System ; Pregnancy ; Shoulder ; Tendons ; Thigh ; Wrist