Abstract
Purpose: :
To study the differences of the innervation between human accessory lacrimal glands and main lacrimal glands
Methods: :
21 accessory lacrimal glands(ALGs) and 10 main lacrimal gland(LG) were excised from 10 autopsy exenterations(aged 20~38,male 9,fema le 1),fixed with 2.5% glutaraldehyde in 0 .1 mol/L phosphate buffer (pH7.4),post-fixed in 1% osmic acid,and embedded in Epon 618.Stained with uranyl acetate and lead citrate,ultrathin sections from each accessory lacrimal gland and main lacrimal gland were examined with TEM-1200EX electron microscope.
Results: :
The same non-myelinated nerve fibers in great number were found in the stroma of ALGs and main LG.The synapse between axon terminals and myoepithelial cells in ALGs and main LG were also compared. The naked axons were seen between the basement membrane and acinar cells in both of them. Axons lay either deep within Schwann cells or ran along the periphery of Schwann cells.The diameters of axon varied 200nm~1µm.The axoplasmic organelles included mitochondria neurotubules and different kinds of vesicles.Some of fine single naked axons invaginated into myoepithelial cells and were identified forming the synapses directly with myoepithelial cells,while others penetrated the basement membrane of acinar cells to pass in between them.The distance between axons and target cells ranged from 10~30nm.In the varicosities of these axon terminals there were many small clear vesicles,with diameters 2 0~50nm,and a few larger granular vesicles,with diameters 80~100nm.The small clear vesicles are considered containing a cetylcholine (ACh) mainly while large granular vesicles containing neuropeptides .So,those axon terminals were considered typical of cholinergic parasympathetic nerve fibers morphologically.
Conclusions: :
Human accessory lacrimal glands are definitely innervated, and the histologic structure of ALGs and main LG are identical and both of them are innervated by nerves typical of cholinergic parasympathetic nerve fibers.
Keywords: lacrimal gland • innervation: neural regulation • eicosanoids