ABSTRACT
omparative anatomy is the study of similarities and differences in the anatomy of different organisms. It is closely related to evolutionary biology and phylogeny.
This research work is aimed at making comparisms between two animals constantly in use in research primarily as models for various human medical conditions and even for production of antibodies for vaccines. The study is aimed at finding the differences and similarities of the guinea pig and wistar rat liver.
Guinea pigs and wistar rats are currently in use in laboratory research as models for various human medical conditions, for virology and toxicological studies just to mention a few. In this study a total number of 5 Guinea pigs and 5 Wistar rats all adult males were used. The mean body weights of the Guinea pigs were 481.4g and 90.80g for the wistar rat. The mean weight for the liver was 17.80g for the Guinea pig and 6.80g for the wistar rat. The mean length of the liver was 5.22cm for the Guinea pig and 1.88 cm for the wistar rat. A gross physical examination of the liver was carried out, the colour, texture, and number of lobes were observed and recorded. Histological study was done using routine (H and E staining) histological techniques. Findings are: Basic histology of the guinea pig and wistar rat liver are similar. Comparatively, the liver of the Guinea pig and Wistar rat studied showed that they are phylogenetically related. Histologically, liver of the experimental animals studied showed basic similar histo-architecture.
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TABLE OF CONTENTS
Title Page ………………………………………………………………………….. i
Declaration …………………………………………………………………………..ii
Certification …………………………………………………………………………iii
Acknowledgement …………………………………………………………………..iv
Abstract …….…………………………………………………………………………v
List of Figures …………………………………………………………………….. vi
List of Plates ………………………………………………………………………..vii
Table of Contents …………………………………………………………………..viii
CHAPTER ONE
1.0 Introduction ………………………………………………………………………1
1.0 The Aim and Objective of the study………………………………………………3
1.0 The Aim of the study ………………………………………………………………3
1.0 The Objectives of the study ……………………………………………………….3
1.0 Justification of the study ………………………….………………………………3
CHAPTER TWO
2.0 Literature Review …………………………………………………………………4
2.1 Comparative Anatomy …………………………………………………………….4
2.2 Guinea Pig…………………………………………………………………………5
2.2.1 Behaviour of Guinea Pigs ………………………………………………………6
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2.2.2Feeding In Guinea Pigs …………………………………………………………7
2.2.3 Habitat of Guinea Pigs………………………………….………………………8
2.3.4 Breeding in Guinea Pig…………………………………………………………8
2.2.5 Scientific Classification of Guinea Pig…………………………..………….…11
2.2.6 Economical Importance of Guinea Pig to Humans……….……………………12
2.3 Wistar Rat ………………………………..………………………………………12
2.3.1 Scientific Classification of Wistar rat ……………………………….…..…….13
2.4 Animals in Research…………………………………………………….…..……14
2.5 The Liver…………………………………………………………….……………17
2.5.1 Embryology of the Liver ………………………………………….……..……17
2.5.2 Gross Anatomy of the Liver…………………………………….……………..18
2.5.3 Hepatic Attachments …………………………………………………………..19
2.5.4 Hepatic Surfaces and Borders…………………………………………………..19
2.6 Histology of the Liver……………………………………………………….……20
2.7 Functions of the Liver……………………………………………….……………22
CHAPTER THREE
3.0 Materials and Methods…………..……………………………………….………25
3.1 Materials …………………………….…………………………………………..25
3.1.1 Study Animals ……………………………………………….…….….………25
3.1.2 Other materials ……………………………………………………………….25
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3.2 Methods ………………………………………………………………………25
3.2.1 Morphologic Studies……………………………………………..…….…..26
3.2.2 Morphometric Study ………………………………………….……………26
3.2.3 Histologic Study ………………………………………….…….…….……26
3.3 Statistical Analysis ………………………………………….…….…….……26
CHAPTER FOUR
4.0 Presentation of Results …………………………..…………….……………..28
4.1 Physical Observation …………………………………..…………….…………28
4.2 Body Weight of Study Animals …………………………………….……..……28
4.3 Gross Anatomical Features of Organs Studied …………………………….…..30
4.4 Morphometry of Organs Studied ………………………………………….……33
4.5 Histoarchitecture of the Liver Studied…………………………………….……34
CHAPTER FIVE
5.0 Discussion ……………………..……….…………..………………….………36
5.1 Physical Observation ………………… …………………………….…………36
5.2 Gross Anatomy ………………..……….………………………….……..……36
5.3 Histological Features …………………………………………………………..37
CHAPTER SIX
6.0 Summary, Conclusion and Recommendation…………….………..…………38
CHAPTER ONE
1.1 INTRODUCTION
Comparative anatomy is the study of similarities and differences in the anatomy of different organisms. It is closely related to evolutionary biology and phylogeny. Comparative anatomy has long served as evidence of evolution. It indicates that various organisms share a common ancestor. Also, it assists scientists in classifying organisms based on similar characteristics or diversity of their anatomical structures. A common example of comparative anatomy is the similar bone structures in the fore limbs of cats, whales, bats and human beings. Even though all these appendages consist of the same basic parts; yet they serve completely different functions (Campbell et al., 2002). The Guinea pig (Cavia porcellus) also called cavy, is specie of rodent belonging to the family caviidae and genus cavia. These animals which do not belong to the pig family originated from the Andes and earlier studies based on biochemistry and hybridization suggested they are domesticated descendants of a closely related specie of cavy such as cavia asperea, cavia tschundii and therefore do not exist naturally in the wild (Weir 1974, Nowak, 1999). Their domestication began around 5000 B.C and because of their popularity as pets and meat source they are now globally distributed. They are indigenous to South America, with fossil records extending as far back as 9000 B.C European colonization of South America lead to their introduction as pets in European and ultimately the world over (Morales, 1994; Vanderlip, 2003).
Biological experimentation on guinea pigs has been carried out since the 17th century. During the 19th and early 20th centuries, the Guinea pig was a popular experimental animal for studying prevalent bacterial diseases such as tuberculosis and diphtheria,
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(Padilla-carlin et al., 2008) resulting in the epithet ‗guinea pig‘ being used to describe a test subject. Guinea pigs are currently in use in research primarily as models for various human medical conditions, for virology and toxicological studies just to mention
Albino Wistar rat is the most common type of Laboratory rat, belonging to the species Rattus norvegicus. This strain was developed at the Wistar Institute in 1906 for use in biological and medical research, and is notably the first rat strain developed to serve as a model organism at a time when laboratories primarily used Musmusculus, or the common House mouse. It is a perfect reserve of all the qualities attributable to domestic rats which includes: tolerant of crowd, calmness, breed earlier, less likely to bite and produce more off-springs (Sharon et al., 1999). The Wistar rat is currently one of the most popular rats strains used for laboratory research. It is characterized by its wide head, long ears, and having a tail length that is always less than its body length. The rat can be feed with regular poultry feed and normal water. The cage does not require a complex construction. All that is needed is a feeding bottle-like source of drinking water, a feeding trough and an aerated environment.
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1.2 THE AIM AND OBJECTIVES OF THE STUDY
1.21 THE AIM OF THE STUDY
The aim was to study the comparative anatomy of the liver of Wistar rat and Guinea pig.
1.22 THE OBJECTIVES OF THE STUDY
i. To comparatively study the morphology and morphometric parameters of the liver, in male guinea pigs and wistar rats.
ii. To comparatively study the histology of the liver, in male guinea pigs and wistar rats.
1.3 JUSTIFICATION OF THE STUDY
i. The economic importance of guinea pig and wistar rat cannot be over emphasized as it serves a laboratory animal, pet and as meat source.
ii. Guinea pig and wistar rat are invaluable resources in biomedical research where they are used as laboratory subjects.
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