Light and scanning electron microscopic study of the tongue in the Bali myna (Leucopsar rothschildi)

Abstract

Introduction: The aim of the present study was to investigate the light and electron
microscopic structure of the tongue in the Bali myna (Leucopsar rothschildi).
Materials & Methods: 6 adult Bali myna (3 males and 3 females) were used in the present
study. Tissue samples from the apex, body and root of the tongue were stained with
hematoxylin and eosin (H&E) and periodic acid Schiff (PAS) and studied using light
microscopy. For scanning electron microscopic studies of the lingual surface, the fixed
samples were rinsed with 0.1M phosphate buffer. Postfixation was made in 1% sodium
tetroxide solution for two hours at 4°C. After dehydration through ethanol and infiltration by
hexamethyl disilazin, the dried specimen was mounted on aluminum stabs and coated with
gold-palladium. The specimens were observed at various angles under a scanning electron
microscope.
Results: The tongue in Bali myna has an elongated structure and is wide and triangular in the
posterior part. Three parts are distinguished in the dorsal surface of the tongue: the apex, the
body and the root. The surface of the organ does not have a median groove. A large number
of needle-shaped processes with equal size and high density are located on both sides of the
apex and anterior part of the body of the tongue. Large caudally directed conical papillae with
a V-shaped arrangement are found between the body and the root of the organ. The surface of
the tongue has no gustatory and lingual papillae. At electron microscopic level, fine microgrooves
can be seen on the surface of the root of the organ. Salivary gland pores are clearly
found on the dorsal surface of the lingual root. The surface of the tongue is lined with
keratinized stratified squamous epithelium in the apex and body of the organ, and with nonkeratinized
stratified squamous epithelium in the root region. A unique feature of the lingual
structure in the Bali myna is that the tubuloalveolar PAS-positive salivary glands are found
only in the root of the organ, and lingual salivary glands are not present in the apex and body
of the organ. Morphological and morphometric features of the tongue do not show any sexual
dimorphism.
Conclusion: Overall, the results showed that the tissue structure of the tongue in Bali myna is
similar to birds such as white-tailed eagles, geese, owls, ostriches and woodpeckers and has
specific characteristics in the region of the apex and the distribution of salivary glands.