Functional anatomy of the lacrimal gland in African black ostrich Struthio camelus domesticus in the embryonic and postnatal period

The aim of the present study was morphological and histochemical analysis of the lacrimal gland (LG) in African black ostrich Struthio camelus domesticus in the embryonic and postnatal period. Studies were conducted on 50 ostriches aged between the 28th day of incubation until 7 months old. Tissue sections were stained with haematoxylin and eosin, Azan trichrome, periodic acid-Schiff, Alcian blue pH 2.5, aldehyde fuchsin and Hale's dialysed iron. The LG in ostrich was classified as a tubulo-acinar type. The primordia of the lobes were determined in the LG structure on the 28th day of incubation, whilst the weakly visible lobes with acini and tubules were observed on the 40th day of incubation. Morphometric studies of the LG showed steady growth, characterised by an increase in both length and width. Histometric measurements of lobe size showed little difference between the first, second and third age groups, whilst in the fourth age group a marked increase in size of lobes was observed. The study showed that, apart from morphological changes, during the growth of the LG the character of acid mucopolysaccharides changed. Sulphated acid mucopolysaccharides were indicated, particularly with aldehyde fuchsin (AF) staining in the fourth age group. The Hale's dialysed iron (HDI) staining showed a low concentration of carboxylated acid mucopolysaccharides in the first and second age groups and a higher concentration in the third and fourth age groups. Periodic acid-Schiff staining (PAS)-positive cells were observed in each age group, but only a small number of cells with a weakly PAS-positive reaction were demonstrated in the first age group.