Devendra Pathak

Toxic effect of formaldehyde on the respiratory organs of rabbits: a light and electron microscopic study.

In this study, the effect of direct exposure of formaldehyde in different concentration was observed in 14 rabbits aged 3-6 months and weighing 1100-1200 g. The animals were divided into two groups with six animals in each group, and two animals were kept as control. The animals of group I were exposed to 10% formalin for 12 weeks and those of group II to 40% formalin solution for 6 weeks. After completion of the experimental periods, the animals were killed and the tissue samples were collected from the nasal cavity, trachea and lungs in 10% neutral buffered formalin and Karnovsky’s fixative to examine the histological and electron microscopic changes in the organs. The mucosal cells of nasal cavity showed loss of cilia and epithelial metaplasia was observed in places. There was vascular congestion and mild subepithelial odema. The tracheal epithelium was organized with hyperchromatic nuclei. There was subepithelial odema along with lymphomononuclear cellular infiltration. There was marked emphysema evident as bulla formation of air spaces due to rupture of interalveolar septum. An increased cellularity of alveolar wall was observed, resulting in its thickening. The epithelial lining of bronchioles showed loss of mucosal folds and hyperplasia of cells along with peribronchial lymphomononuclear cellular infiltration. Thickening of wall of blood vessels was evident. Congestion and haemorrhages were observed in places. It is concluded that the histopathological changes were more remarkable in the animals exposed to 40% formaldehyde for short duration than the animals exposed to 10% formaldehyde for longer duration with a more severe effect on the upper part of the respiratory tract than the lower one.

Light and scanning electron microscopy studies of quail tongues

The present study was conducted on the tongues of six Punjab white quails. The tissues from the apex, body and root of the tongue were processed for paraffin sectioning and scanning electron microscopy studies. The tongue was triangular in shape having an apex, body and root. The dorsal surface of the apex and body was smooth whereas large lingual conical papillae were located symmetrically and converging in median line between the body and the root. There was an additional layer of conical papillae composed of two large papillae behind the main row of papillae. The tongue was lined by stratified squamous epithelium which was keratinised at the apex. The anterior lingual salivary glands were mainly serous type whereas the posterior salivary glands were mucous type. There were topographical differences in the size, shape and appearance of the exfoliated superficial cells of the dorsal surface epithelium in the apex and body of the tongue.