Essence of keratin in lips and associated structures of a freshwater fish Puntius sophore in relation to its feeding ecology: Histochemistry and scanning electron microscope investigation
There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.
Abstract
Morphological specializations in the lips and associated structures of Puntius sophore
were examined by scanning electron microscopy and histochemically. The upper lip (UL),
in P. sophore, is associated with the horny upper jaw sheath (HUJS) on its ventral
side and with the rostral cap (RC) on its dorsal side through a thin and extensive
fold of skin (FSUR). The lower lip (LL) is greatly enlarged, conspicuous and associated
with horny lower jaw sheath (HLJS) on the dorsal side and ventrally continues with
ventral head skin (VHS). On the lateral sides there is a thin and extensive fold of
skin (FSLS) between the lower lip and VHS. In contrast to the mucogenic epithelia
of the UL, LL, the RC and fold of skins, the horny jaw sheaths are keratinized in
nature and surface epithelial cells are characteristically modified into unculi. The
UL and the LL are equipped with epithelial cells (EC), mucous cells (MC) and taste
buds (TB) while in addition to these cells club cells (CC) are also present in the
RC. Keratin found in unculi is an extremely strong protein which is tough and insoluble,
they form the hard but un-mineralized structures. Keratin in unculi could be regarded
as an adaptation for browsing or scraping food materials from the substrate as the
fish grubs about the bottom. The elaboration of mucus is considered to lubricate the
surface and protect the epithelia from abrasions. Taste buds are associated to locate
and select palatable food and to trigger a 'pick-up' reflex.