Abstract
Abstract: :
Purpose: Acute section of the parasympathetic preganglionic nerve produces a long lasting dry eye condition in the rabbit. The purpose of this study was to evaluate the effects of this surgery on the tarsal conjunctiva. Methods: The preganglionic input to the pterygopalatine ganglion was separated unilaterally in New Zealand white rabbits under deep anesthesia as described (ARVO 2001 nr 315). The structure of conjunctival lacrimal gland tissue was analyzed by transmission electron microscopy (TEM) and light microscopy (LM). To evaluate the status of the eye, Schirmer's test, fluorescein and Rose Bengal staining were carried out. At 3 months after surgery, cell proliferation and tarsal conjunctiva were studied. BrdU (200mg/kg) was injected intravenously 3 hours prior to sacrifice (n=3). A fluorescence method was used to detect BrdU-positive cells in the conjunctiva. Also, immunohistochemistry of the lower lid was carried out for FGF 10 and 7, and Pax 6. Results: At 1 week after surgery tear flow was reduced to 26% of normal compared to the contra-lateral side (p<0.005). Beginning at 3-4 weeks after surgery, tear flow on the denervated side gradually recovered, reaching about 60% at 3 months. Fluorescein and Rose Bengal staining of the cornea were less at 3 months when compared to 1 week. Using LM to analyze sections of the entire lower lid, new areas of lacrimal tissue were seen in the tarsal conjunctiva. By TEM these were found to contain well-developed lumen and acinar cells with light staining of the secretory granules. BrdU, FGF10 and 7, and Pax 6 were detected in the newly developing lacrimal gland-like acinar cell area. Conclusion: New conjunctival lacrimal tissue with characteristics different from accessory lacrimal gland appears to develop in response to the experimental state. The cellular origin of the additional lacrimal tissue is unclear, but does not appear to be the existing accessory lacrimal gland.
Keywords: 441 innervation: neural regulation • 365 conjunctiva • 452 lacrimal gland