The effect of ageing on the morphology and physiology of the lacrimal gland

Abstract

Tears are formed by a group of glands and ocular epithelia collectively named the lacnmal gland system. The lacrimal glands are paired orbital structures which in the rat consist of an intraorbital and exorbital component. The exorbital gland is responsible for secreting the aqueous components of the tear film, consisting of water, electrolytes and proteins which are responsible for keeping the cornea buffered, lubricated, nourished and protected. Ageing has been associated with lacrimal gland dysfunction, resulting in reduced aqueous tear production, which is associated with dry eye conditions.
However, very little is known about ageing effects on the lacrimal gland and in particular the lacrimal gland acinar cells.
This study employed light and electron microscopy, immunohistochemical, radiobiological and physiological techniques to investigate ageing changes in the morphology and function of the lacrimal gland and acinar cells. In all experiments animals of 3-5 months were considered normal, control.
The light microscopical studies revealed that with ageing to 28 months the gland underwent progressive morphological changes, including; thickening and deposition of the interlobular connective tissue, inflammatory cell infiltration, inflammation, necrosis, enlargement of ducts, patchy destruction of acinar, vascular and ductal tissues and luminal swelling of the acini. These changes were most apparent at 20, 24 and 28 months, only changes to the interlobular connective tissue was observed at 12 months and very little was observed at 9 months. However, in all age groups there was a change in the
type and distribution of the acinar cell. Three distinct types of acinar cells were observed in the lacrimal glands; serous, seromucous and mucous (Draper et aL, 1998; 1999).