Abstract
Purpose: :
Carbons and enormous amounts of energy are required for the synthesis of extremely long fatty acids and fatty alcohols by the meibomian gland. Given that the maturing acinar cells are progressively displaced from their scanty blood supply, easy access to carbon sources and oxygen for energy is not apparent. Ultrastructural studies have been carried out to resolve this conundrum.
Methods: :
Rat meibomian glands were fixed in buffered aldehydes, embedded in plastic, and sectioned for electron microscopy.
Results: :
Between the apical region of the basal cells and maturing acinar cells was a large space with fingerlike cytoplasmic projections. This appears to be due to lipid vesicles being transported from the basal cells into the intercellular space and then being taken up by the more mature acinar cells. Large desmosomes between the basal cells and maturing acinar cells maintain the structural integrity. There did not appear to transfer of lipids between mature acinar cells.
Conclusions: :
Our results suggest that lipids produced by the basal cells are being transported via the apical region to more mature acinar cells located more centrally in the acinus. In these cells, the lipid vesicles fuse into larger vesicles and it is likely that the lipids are further modified in these acinar cells. Such a mechanism means that the lipid production mainly occurs in the basal cells which have easy access to carbons and oxygen.
Keywords: lipids • microscopy: electron microscopy