1.1 BACKGROUND OF STUDY
The detailed structural studies on
different organ system of domestic animals are giving important in
contemporary biological science. These have implication on conservation
and propagation and also form data base of scientific information.The
present study describe the comparative histological study and of a
The cat is taxonomically in the kingdom animal, phylum chordate, class mammalian, order carnivore, family viverridae.
The cat is a smaller animal whose length is 3ft and has a tail size of 1ft. it weighs from 6-8ib.
The general colourare brownish or olive
grey to light grey. They are longitudinal dark stripes and rows of spots
along the body. Its main diet is rats, lizards, small birds, insects,
fruits and berries.
The comparative histology of the study
of the tongue would show the micro-anatomical and structural variation
that appeared to represent adaptations to their various feeding
pattern.The cat tongue has sharp spines,or papillae, useful for
retaining and ripping flesh from a carcass. These papillae are small
backward facing hooks that contains keratin whichalso assist in there
groom. The cat papillae contain tiny holes or pores that lead to tastes
bud consist of muscles. The bulk of the tongue consists of muscles
bundles mixed with connective (strong/ tough) and adipose (fat) tissues.
It has many blood vessels and bleed profusely when lacerated. The
tongue is surrounded by the openings of the duct of the salivary glands,
which pores there secretion (saliva) into the oral cavity.
The tongue (lingua) occupies the ventral
aspect of the oral cavity and oropharynx. It is involved with grooming,
lapping, prehension and manipulating food in the oral cavity. It is
also involved in the deglutition reflex and vocalisation. The tongue is
capable of vigorous and precise movements due to the apex being free of
attachments to the oral cavity.
The shape and structure of the
tongue differ significantly among animal species, reflecting the various
functions of each respective tongue (Iwasaki, 2002; Santos et al.,
2011). In the anatomy of the tongue, three parts may be distinguished:
the apex, the body and the root (Jackowiak and Godynicki, 2005;
Dehkordiet al., 2010). On the surface of tongue, there are various kinds
of lingual papillaeseach having different morphological structure and
shape. Distribution of these lingual papillae has been considered to be
related to species eating habits and vocalization (Fawcett, 1986; Park
et al., 2009). All the papillae are covered by stratified squamous
epithelium that differs by the thickness and keratinization only
(Iwasaki and Miyata, 1985; Wassif, 2001).
Notably, the tongue of carnivorous
animals have filiform, fungiform and Valliate but lacks foliate
papillae(Chamorro, De Paz, Sandoval et al., 1986);Kobayashi, Kamakura
and Takahashi, 1995;Qayyum and Beg, 1975).
1.1.1 FEEDING MECHANISM
The feeding mechanism is clearly an
important factor that determines the success of adaptation of
vertebrates to their environment and of their persistence through
procreation (Roth & Wake, 1989). In feeding, the tongue plays a
principal role, together with other organs within and near the oral
cavity, in particular in cat. The tongue has a characteristic form in
cat. Cat have a slight elevation of the mucosa on the floor of the mouth
this structure contain voluntary muscles.
According to Roth and Wake, (1989),
Darwish, (2012), the tongue is often considered a key innovation in the
evolution of a terrestrial lifestyle as it allows animals to transport
food particles through the oral cavity. Also, there are fairly strong
correlations between tongue anatomy and its functional roles (e.g., food
transport and manipulation), and the environmental conditions in which
animals use their tongues.
The tongue consists largely of skeletal
muscle, partly invested by mucosa. The lingual mucosa of the inferior
surface is then, smooth and like that in much of the rest of the oral
cavity. The mucosa of the pharyngeal part of the dorsum contains many
lymphoid follicles. In the oral part the dorsal mucosa is somewhat
thicker ventrally and laterally, it is adherent to muscular tissue and
covered by numerous papillae. It consists of connective tissue (Lamina
propria) and stratified squamous epithelium. Which also covers each
papilla, (Health et al., 1993).
The lamina propria is a dense fibrous
connective tissue; with numerous elastic fibres, united to similar
tissue which spreads between the lingual muscle fasciculi, it contains
the ramifications of numerous vessels and nerves from which the papillae
are supplied and also large lymph plexus and lingual glands. The
epithelium varies from parakeratinized stratified s squamous epithelium
posteriorly, to fully keratinized epithelium overlying the
filiformpapiliae more anteriorly, these features appears to be related
to the fact that the apex of the tongue is subject to greater
dehydration than the posterior and ventral parts and is more abraded
during mastication (Health et al., 1993).
STRUCTUREOF THE TONGUE A CARNIVOROUS CAT
The tongue is skeletal muscle dorsally
and structural fat surrounded by a cartilaginous sheath forming lyssa
(canids only) ventrally. It has an attached root and body with a free
apex. The frenulum (fold of mucosa) attaches the body of the tongue to
the floor of the oral cavity.The root of tongue is attached to the hyoid
bone. In the horse and dog, the tongue is 'u' shaped, becoming broader
towards the tip. The furrow in the centre of the canidtongue is called
the median sulcus.
FUNCTIONS OF THE TONGUE OF A CARNIVOROUS CAT
- The tongue is an important grooming tool for cat
- The tongue helps reduce body temperature in cat
- Its severs as ladle for lapping water and other liquids into the mouth during drinking
- The taste bud of the tongue are important in detection and sense of taste
- The tongue assist in chewing and swallowing of food
- The tongue is used mainly for guiding food and water into the throat
1.2 RATIONALE OF STUDY
The comparative histological study has never been undertaken by any student in Delta State University, Abraka.
The topic is aimed to compare the
histological and morphological structure of the tongue of the selected
vertebrates.The fundamental reason of the study to be carried out is to
compare the histological structure of tongues of carnivorous cat (Felixdomesica) and some other vertebrates in relation to their feeding habits.
1.3 SIGNIFICANT OF PROBLEM
Comparative gross anatomy have long been
used to compare the structural relationship between animals groups.
Details of the histological comparisons of tongue of various classes of
vertebrate need to be examined as similarities and differences in the
gross morphology of species may not totally explain species relatedness.
1.4 SIGNIFICANT OF STUDY
1 It helps provides data concerning the topics for further research
2 It helps relates the structure and feeding habits of cat and other vertebrates
1.5 OBJECTIVES OF THE STUDY
The general objective of this study is
to compare the histological structure of tongue of a carnivore, cat and
some other vertebrates in relation to their feeding habits.
The specific objective is to compare the histological feature and feeding habits of the vertebrae through experiment.
1.6 RESEARCH QUESTION
1 Is there a significant difference between feeding habits and structure of the tongue of cat some with other vertebrates?
2 What is the relationship between the feeding habit and structure of the tongue ofvertebrates?
1.7 LIMITATION OF THE STUDY/SCOPE
The scope of this research was to
compare the tongue of four (4) different vertebrates (cat, rat, rabbit
and lizard) in relation to their feeding habits. The study was
limited to the tongue of the vertebrate selected and did not study any
pathology of the tongue.
1.8 OPERATIONAL DEFINITION OF TERMS
- COMPARATIVE: This is the use of comparison as study method or founded on somethingusing it, (oxford dictionary).
- HISTOLOGICAL: This is the study of microscopic
structure, chemical comparison and function of tissues or system in
animals. (Oxford dictionary)
- VERTEBRATES: These are animals that have backbone. (oxford dictionary)
- TONGUE: This is a flexible muscular organ in the
mouth that is used to move foodaround for tasting and that is moved into
various positions to modify the flow of airfrom the lungs in order to
produce different sounds in speech.Speaking, etc
- CAT: These is a small animal commonly kept as a house pet