Marfurt C F, Ellis L C
Northwest Center for Medical Education, Indiana University School of Medicine, Gary 46408.
J Comp Neurol. 1993 Oct 22;336(4):517-31. doi: 10.1002/cne.903360405.
The sympathetic innervation of the mammalian cornea is thought to play an important role in the regulation of epithelial ion transport, mitogenesis, and wound healing following corneal injuries. Anatomically, the three-dimensional organization and relative density of corneal sympathetic innervation in many species remains inadequately described. In the present study, the sympathetic innervation of five different mammals (guinea pig, rat, mouse, hamster, and human) was studied in corneas sectioned parallel to the main axis of fiber orientation by labeling the fibers immunohistochemically with antiserum against tyrosine hydroxylase and an avidin-biotin-diaminobenzidine technique. The results showed that each species displayed a distinctive pattern and density of tyrosine hydroxylase immunoreactive (TH-IR) corneal innervation that was unique to that species. The overall level of TH-IR innervation was highest in the guinea pig, moderate in the human, hamster, and rat, and lowest in the mouse. In all species examined, TH-IR nerves were most numerous in the corneoscleral limbus where they either formed intimate associations with blood vessels or coursed through the connective tissue matrix apparently unrelated to vascular elements. Other TH-IR nerves entered the cornea proper in radially directed stromal nerve bundles to give rise to subepithelial plexuses of varying complexity. Occasional intraepithelial penetrations were observed in the guinea pig, human, and rat. Removal of the superior cervical ganglion resulted in the total loss of TH-IR staining from guinea pig and hamster corneas and in the substantial but incomplete loss of TH-IR staining from rat and mouse corneas, thus demonstrating their predominantly sympathetic origin. Combined sympathetic and sensory ocular denervation in the rat eliminated almost all corneal and limbal TH-IR immunostaining, thus suggesting a minor TH-IR sensory component in this species. In agreement with this conclusion, small numbers of TH-IR sensory neurons and an abundance of TH-IR fibers were observed in the trigeminal ganglia of the rat and guinea pig. Removal of the rat main ciliary ganglion resulted in the loss of additional TH-IR fibers from the chamber angle and iris, thereby confirming a partial parasympathetic contribution to the rat iridial TH-IR innervation. Following unilateral removal of the superior cervical ganglion in rats and guinea pigs, the contralateral cornea contained increased numbers of TH-IR nerves, suggesting an upregulation of tyrosine hydroxylase (TH) expression in some contralateral axons.(ABSTRACT TRUNCATED AT 400 WORDS)
哺乳动物角膜的交感神经支配被认为在角膜上皮离子转运、有丝分裂以及角膜损伤后的伤口愈合调节中发挥重要作用。从解剖学角度来看，许多物种角膜交感神经支配的三维组织结构和相对密度仍未得到充分描述。在本研究中，通过使用抗酪氨酸羟化酶抗血清和抗生物素蛋白-生物素-二氨基联苯胺技术对纤维进行免疫组织化学标记，研究了五种不同哺乳动物（豚鼠、大鼠、小鼠、仓鼠和人类）在平行于纤维取向主轴切片的角膜中的交感神经支配。结果表明，每个物种都呈现出独特的酪氨酸羟化酶免疫反应性（TH-IR）角膜神经支配模式和密度，该模式和密度是该物种所特有的。豚鼠中TH-IR神经支配的总体水平最高，人类、仓鼠和大鼠中的水平中等，小鼠中的水平最低。在所有检查的物种中，TH-IR神经在角膜缘最为密集，它们要么与血管形成紧密联系，要么穿过明显与血管成分无关的结缔组织基质。其他TH-IR神经以放射状的基质神经束进入角膜实质，形成不同复杂程度的上皮下丛。在豚鼠、人类和大鼠中偶尔观察到上皮内穿透。切除颈上神经节后，豚鼠和仓鼠角膜中的TH-IR染色完全消失，大鼠和小鼠角膜中的TH-IR染色大量但未完全消失，从而证明它们主要起源于交感神经。大鼠中交感神经和感觉性眼神经联合去神经支配几乎消除了所有角膜和角膜缘的TH-IR免疫染色，因此表明该物种中存在少量TH-IR感觉成分。与该结论一致，在大鼠和豚鼠的三叉神经节中观察到少量TH-IR感觉神经元和大量TH-IR纤维。切除大鼠主要睫状神经节后，房角和虹膜中的额外TH-IR纤维消失，从而证实副交感神经对大鼠虹膜TH-IR神经支配有部分贡献。在大鼠和豚鼠单侧切除颈上神经节后，对侧角膜中TH-IR神经数量增加，表明一些对侧轴突中酪氨酸羟化酶（TH）表达上调。（摘要截于400字）
