CHAPTER I
A comparative study of the skin of some fresh water cat fishes
Introduction
Fish skin has been the subject of considerable interest from the
standpoint of comparative anatomy, and a review of literature yields several
monographs or collection of articles dealing with the dermatology of fishes.
But there are relatively few works on the skin of cat fishes and a few works
done concentrated mainly on the microanatomy of the epidermal cell types.
Fish epidermis though in some cases capable of synthesizing Keratin
(Mittal and Whitear, 1979; Mittal and Banerjee, 1980; Ralphs and Benjamin,
1992) is in general unkeratinized and is characterised by large number of
unicellular secretory glands, i e., mucous cells, succiform cells, club cells,
columnar cells, saccular cells and ionocytes interspersed between the main
structural component of the epidermis, the epithelial cells (Mittal and
Banerjee, 1980; Mittal et al., 1980; Mittal et al., 1981; Whitear and Mittal,
1983; Ahmed and Tan, 1991; Northcott and James, 1996; Ottesen and Olafsen,
1997); the superficial epithelial cells remain metabolically active and secrete
an extra cellular cuticular coat (Whitear, 1970).
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Various cellular components of the epidermis of fishes vary in
abundance arid dimensions, between species. This may be related to the mode
of living of the fish and its response to the environment.
Among the numerous functions of the skin, none is more important
than protecting the organism from environmental hazards even while
maintaining it in uninterrupted communication with the environment. The
remarkable ability of epidermis to adapt to its surroundings accounts not
only for the seemingly endless structural and functional differences behveen
the various species but for certain basic patterns common to all.
Variations occur in the skin of fishes, under various internal as well
as external factors, which will be dealt in later chapters.
The present report is a comparative study of the skin of some cat
fishes - Clarias barrachl~s,Heteropnetlstes fossilis and Mystus grrlio. It would
be useful as a preliminary study for further detailed analysis of the skin
structure in these fishes.
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Fig. 1-3
Fishes selected for the study
Fig. 1
Claias batrachus
Fig. 2
Heteropneustes fossiiis
Fig. 3
Mystus gulio
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Materials and Methods
Live specimens of Clarias batrachzis (Linnaeus) (Claridae,
Siluriformes), Heteropneustes fossilis (Bloch) (Heteropneustidae, Siluriformes)
and Mystzrs gulio (Hamilton) (Bagridae, Silurifomes) (figl, 2, 3) of average
length 18 cm, 16 cm and 12 crn respectively were collected during the premonsoon period from the ponds and rivers at Patbanamthitta (latitude
9"15'3OW,longitude 76O47'3OU),Kerala. Five fishes from each species were
sacrificed. Skin fragments (approximately 5
x
8 mm) were cut from the back
of the fish in between the anterior end of the dorsal fin and lateral line canal
(Fig. 4) and fixed in 10% neutral buffered formalin. Graded ethanol was
used as dehydrating agent and xylene for clearing. Paraffin sections were
cut at 5 pm and stained with Ehrlich's haematoxylin or Heldenhains Iron
haematoxylin and eosin for routine histological analysis (Pearse, 1961, 1985).
Fig. 4 Reglon of the body marked by * from where skin fragment was excised
G
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-
Dimensions of the skin layers and various cell types were made using
calibrated ocular micrometer. Since the epidermal cells are not uniformly
distributed they were accounted from the crowded sites. Counts were made
from 1 mm length and full depth of the epidermis. Standard statistical
methods, of mean and standard deviation, based on random sampling- of four
different sites on each tissue sample, from five fishes of each species were
talcen into consideration.
Observations
The skin of all the fishes investigated is devoid of scales and consists
of three principal layers- the epidermis, the dermis (corium) and the subcutis;
the thickness of which varies among the fishes as shown in Table 1.
Table I . Comparative thickness of the skin layers in the cat fishes
Cat fish
Thickness [mean (k S.D)p]
Length
of fish (mm)
Epidermis
Dermis
Subcuris
Clarias ha~rachtrs
180
97.6 (9.17)
306.5 (12.97)
60.65 (6.29)
Heleropnetrsres jossilfs
180
94.3 17.82)
280 (6.92)
55.31 (9.81)
Mysrtis gtrlio
120
48.5 (8.1;)
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136.95 (9.41)
18.65 (-1.41)
Table 2 . Terminology u s e d b y v a r i o u s workers f o r different Cellular
C o m p o n e n t s o f Fish
Terminology
used in the
present study
Terminology used
previously
Reference
Epithelial
cells
epidermis zellen
Filament containing cells
Leyding (1851)
Henrikson & Matoltsy (1968a)
Squamous cells
Brown & Wellings (1970)
Keratinocytes
Parakkal & Alexander (1972)
Principal epidermal cells
Albanese-Carmignani &
Zaccone (1 974)
Polygonal cells
Mittal & Banerjee (1974)
Malpighian cells
Bullock & Roberts (1975)
Robert & Bullock (1980)
Pavement cells
Iger & Abraham (1990)
Epithelial cells
Bhatti (1938); Junqueira,
Toledo & Porter (1 970);
Whitear (1971); Mittal &
Banerjee (1980); Mittal,
Whitear & Agarwal (1980);
Whitear (1986).
Kleinsten Schleirnzellen
Becherzellen
Leydig (1851)
Schultze (1861)
Cellules muqueuses
Bertin (1958)
Mucous
cells
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Club cells
Goblet cells
Whitear (1 986), Burton &
Burton (1989)
Mucous cells
Bhatti (1938), Henrikson &
Matoltsy (1968b),
Downing & Novalis (1971a),
Mittal & Banerjee (1980),
Mittal, Whitear & Agarwal(1980),
Zaccone & Lo Cascio (1981),
Imaki & Chavin (1 984),
Singh & Mittal (1990).
Struess mann, Nin & Takashima
(1994) Singh, Bhatt &
Bahuguna (1 995).
Grosseren schleimzellen
Leydig (1851)
Kolbenformige Zellen
Schultze (1861)
Kolbenzellen
Schulze (1867)
Leyding cells
Rauther (1907)
Cellules Sereuses
Claviformes
Goblet cells
Jakubowski (1958)
Schreckstoffzellen
or alarm substance cells
Pfeiffer (1960) Struessmann, Nin
& Takashima (1994)
Giant cells
Mittal & Munshi (1970)
Club Cells
Wright (1 984); Henrikson &
Matoltsy ( 1 9 6 8 ~ )Downing
:
&
Novalis (1971 b), Roberts &
Bullock (19SO);whitear& Mitta.l(l983);
Whitear (1986); Singh & Mittal(1990).
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Lymphocytes
Wanderzellen
Reid (1 894)
Small lymphocytes
Olmsted (1 920)
Leucocytes
Kann (1926)
Wandering connective
tissue cells or Fibroblasts
Bhatti (1938)
Spherical basal cells
Mittai (1 968)
Lymphocytes
Percy (1 970); Graupner &
Fischer (1 933); Mittal &
Munshi (1 971); Mittal,
Whitear & Agarwal (1980).
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0
Epidermis
The epidermis is separated from the underlying dermis by a thin noncellular basement membrane. The epidermis is a stratified epithelium which
may be divided roughly into three layers viz, basal layer or stratum
germinativum, middle layer and outer layer. The thickness of the epidermis
is mainly due to the middle layer. Mainly there are four types of cells present
in the epidermis which were variously named by various workers as shown
in Table 2.
Epithelial cells
Epithelial cells are very numerous, present in the three layers of the
epidermis. However they are more abundant in the outer layer of the
epidermis. These cells are, in general, polygonal in shape. In the outer layer
of the epidermis these cells are, however, vertically compressed or acquire
flattened shape (Fig.6,8,10). In the middle layer the epithelial cells are
vertically elongated due to the lateral pressure exerted by the club cells
(Fig.6,lO).
The basal layer of the epithelial cells in
".
investigated are generally columnar in shape and arrange&in single
restins on the basement membrane (pig.6,10).
11
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The average dimension of the epithelial cells in the three layers of
the epidermis in the fishes investigated is summarised in Table 3.
Table 3. Dimensions of epthelial cells in the cat fishes
Dimensions of epithelial cells [mean (i S.D)prn ]
Length of
Cat fish
fisn
jmm)
Middle layer
Outer la!.er
Height
Width
Height
Width
Basal layer
Height
Width
C. batrachus
180
4.45 (1.00) 8.95 (1.43) 11.15 (0.93) 5.6 (0.68) 6.5 (1.05) 5.2 (1.01)
ilf. gglllio
120
5.35 (1.45) 8.25 (0.98) 10.2 (0.86) 5.5 (0.79) 7.33 (1.12) 4.5 (0.74)
ht. ~ossilis
IS0
4.25 (0.71) 6.16 (0.83) 10.72 (0.96) 6.12 (0.85) 6.23 (1.22) 5.04 (0.96)
The cytoplasm is homogeneous and takes slightly eosinophilic colour
in haematoxylin-eosin.
The nuclei are oval, spherical or flattened and are centrally placed.
They, however, acquire pycnotic appearance at the outer free margins. They
stain blue in haematoxylin-eosln. On the outer surface the epithelial cells,
on the completion of their life cycle are exfoliated either singly or in small
flakes.
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Mucous Cells
The mucous cells, though distributed throughout the epidermis are,
in general, concentrated mainly in the outer layer of the epidermis often
releasing their secretory contents profusely at the surface by a small pore. In
C. batrachzrs and H. fossilis, the outer layer is densely populated with fully
differentiated well developed mucous cells which are often closely
approximated and are regularly arranged in single row. Here they appear to
be flask shaped.
In the middle layer of the epidermis, large, well differentiated and
rounded mucous cells, though observed in C. batracl~trsand H. fossrlzs,
concentrated mainly in the middle layer are relatively very few in number
and smaller in size in M. gzrlro Such cells could not be located in the basal
layer of the epidermis in any of the the fishes investigated.
The average density of mucous cells in the total thickness and lmm
length of the epidermis, their average diameter and volume are summarised
in Table 4.
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Table 4. Densib and diameter of mucous cells
Catfish
fish lenth
Density
Diameter
pm (+ S.D)
(mm)
C. batrachtrs
180
44.95 (6.13)
15.2 (1.67)
H.fossilis
160
38.18 (7.45)
13.8 (3.16)
M. gzrlio
120
18.7 (2.27)
9.4 (3.15)
These values are based on the micrometric measurements of the
middle layer mucous cells which appear spherical and do not open to the
surface to release their contents.
The mucous cells are filled with vacuolated basophilic contents which
push the nucleus and the cytoplasm at the periphery.The nucleus of each
mucous cell appears flat or crescenti'c in outline and occupies its basal part.
In general, the nuclei of these cells stain blue in haematoxylin-eosin.
Club Cells
The club cells, characterised by their unusually large size each having
a centrally placed nucleus, are one of the most conspicuous cells in the
epidermis of the cat fishes investigated. These cells characteristically show
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variation in their shape and size at different levels of the epidermis. The
club cells are in general, rounded or elongated in shape.
The contents of these cells appear homogeneous, finely granular and
are slightly eosinophilic in haemotoxylin-eosin and exhibits variable degree
of shrinkage and vacuolisation due to fixation.
The nuclei of the club cells are, in general, rounded, healthy and
blue in appearance. Sometimes they appear shrunken, irregular in outline
and pycnotic. The club cells of these fishes though uninucleate may
sometimes be found having two nuclei very close to each other (fig. 6.)
In all the cat fishes investigated, the club cells are distributed evenly
throughout in the epidermis and occasionally reach upto the basement
membrane as in C. barrachzrs. In Myst~rsthe club cells are restricted mainly
in the middle layer of the epidermis. In C. batrachus and H. fossilis they
occur also in the outer layer epidermis. The density of the club cells is more
in the epidermis of H.fossilis than M. gzrlio which is greater than that in C.
batrachzrs. The average density and dimensions of the club cells in the
epidermis are summarised in Table 5.
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Table 5. Density and dimensions of the club cells i n the epidermis
Catfish
C.batrachus
H. fossilrs
length of
Club cell
fish in mm
Density
180
40.60(4.24)
81.55(5.92)
65 (6.09)
160
56.55 (6.72)
76.15 (7.12)
52.04 (5.61)
120
48.9 (4.62)
37.2 (5.98)
24.5 (3.69)
Dimensions of Club cells
i
M. gulio
i
1
i
Lymphocytes
Lymphocytes, in general, are observed in large numbers enclosed
within irregular shaped lymphatic spaces in the epidermis of C. barrachz~s,
H. fossilrs and M. gzrlio (Fig.5,8,10). Generally one or two lymphocytes are
present inside each lymphatic space. They are, however, relatively few in
the epidermis o f M . gzrlio where lymphatic spaces are little or absent. These
are mainly restricted in the lower layers of the epidermis lying between the
basal layer epithelial cells. The average dimensions of the lymphocytes in
the cat fishes is approximately similar as in Table 6 .
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Table 6. Dimensions of the Lymphocytes in the epidermis
Length of
Cat fish
C. batrachus
H. fossilis
M. gulio
/
1
Mean Dimensions of Lymphocytes
fish in mm
Height [(*S.D)pm]
Width[(*S.D)pm]
180
4.675 (0.57)
3.725 (0.44)
160
120
1
1
4.51 (0.76)
4.85 (0.81)
1
1
3.625 (0.33)
3.575 (0.44)
I
I
The small amount of cytoplasm surrounding the darkly stained nuclei
of these cells, is homogeneous and takes faint eosinophilic colour in
haematoxylin-eosin.
The nuclei of these cells are rounded and centrally placed with densely
packed nuclear material.They stain dark blue in haematoxylin eosin.
Dermis
The dermis may be divided into two layers-the outer stratum laxum
(stratum vasculare) and the inner stratum compactum. Such a distinction is
very clear in C. batrachus, and in H. fossrl~s(Fig. 7) but very feeble in
M. g~rlio.In C'. batrachtrs where there is distinct stratum laxum and stratum
compactum. their thickness is not uniform. Hence the measurements of the
two strata are taken together in the three fishes (Table 1).
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Stratum laxum
The stratum laxum is not clearly differentiated from the under lying
stratum compactum. The part of the dermis lying immediately below the
basement membrane, composed of comparatively loosely arranged connective
tissue fibres richly supplied with fine blood capillaries and nerves, may be
termed as stratum laxum. Pigment cells are also discernible in this region of
the dermis. Dermal papillae of variable shape. length and thickness are very
often seen arising from the outer surface of this layer (Fig.7,9). The papillae
penetrate deep into the epidermis. They, however, do not break their way
through the basement membrane and the basal layer of the epidermis.The
dermal papillae are richly supplied with fine blood capillaries and are mostly
associated w ~ t hthe taste buds. Pigment cells are also present in the papillae.
The stratum vasculare are not clear in the skin of M. gulio.
Stratum compactum
The stratum compactuIn adds to the main thickness of the dermis. It
forms the main part of the dermis in M. grrlio. It is mainly composed of
coarse connective tissue fibre bundles, arranged parallel to the body. surface.
A few fibre bundles, arranged vertically at intervals are also frequently
observed in this layer. Branches from the main blood capillaries and nerves
in the subcutis traverse through this layer and supply the fine blood capillaries
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in the stratum laxum. But they are relatively less in H. fossilis and ver). lirrls
in M. gzrlro. Scattered in the stratum compactum, a few branched pi-ment
cells are discernible. This also is very little in M. grilio.
The dermis of C. barrachtrs of large size (above 240 mm in len-d)
contains fat cells arranged in small groups between the connective tissue
fibre bundles, towards the outer layer, in stratum compactum (mentioned in
chapter 11, fig. 13). These cells, however, could not be observed in the stratum
compactum of smaller fishes (180 mm length).
Subcutis
This is the innermost layer of the skin and is situated behveen the
stratum compactum and the muscle (fig.7 ). A large number of blood 1-essels
and nerves may be found in this layer. In routine haematoxylin eosin
preparations the subcutis layer invariably sllows some empty spacs n-hich
are occupied by fat cells. A few connective tissue fibre bundles arisinz from
the dermis pass through this layer and penetrate deep in between muscle
bundles at regular intervals as thick connective tissue strands-the myosepta.
While in C. batrachrrs and H. fossilis this layer is thick and disthct, it is
comparative1y thin in M. gzrlio (Table 1).
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Discussion
The integument of the fishes investigated comprise three principal
layers-the epidermis, the dermis and the subcutis. According to Rabl (193 1)
the subcutis is present in all fishes except in Amra calva. Bhatti (1938),
Becker (1941), Jakubowski (1960a,b) and Szabo (1965) made no reference
of this layer in their descriptions. Liem (1967) has recognised subcutis as
one of the principal layers of the skin ofMonopter~rsalbus. Mittal and Munshi
(1970a) found a poorly developed subcutis in B. bagarizrs. In H. fossilis and
C. batrachlrs this layer is well differentiated but in Mystzrs gzrlio this layer is
very thin and inconspicuous.
In the fishes investigated, the epidermis may further be divided into
three main layers, - the outermost epithelial coverage, the middle layer and
the basal layer (stratum germinativum) Jakubowski (1958, 1960a,b) while
studying the vascularisation of skin of different fishes has also recognised
these three layers. Sing11 and Mittal(1990) reported these three layers in the
skin of Indian major carps. Szabo (1965) has described four principal layers
of cells in the epidermis of certain electric cat fishes.
The surface of the body of the fishes investigated is found to contain
a layer of slime in which many nuclei of the dehisced epithelial cells may be
observed. This indicates that there is a continuous renewal of the epidermal
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cells at the surface. The epidermal cells at the surface of the fishes
investigated is composed of vertically compressed epithelial cells. It forms
a continuous covering of the surface. It is interspersed with mature mucous
cells opening to the surface.
The middle layer of the epidermis in the fishes investigated is mainly
composed of club cells and spherical mucous cells, in addition to vertically
elongated epithelial cells. The p r i m a ~ yfunction of the epidermis is protection
against environmental hazards. In fish, this function is generally attributed
mainly to the gland cells secreting their contents on the surface. A similarity
may be established between the overall density of the mucous cells and the
club cells in the three catfishes. In C. batrachzrs and H. fossilis the mucous
cells are relatively large and greater in abundance. In contrast in the epidermis
of M. gzrlio the mucous cells are much smaller and lesser in density and
restricted to the outer layer. It appears that high density of club cells in M.
gzrlio may compensate for the smaller and sparser mucous cells in providing
an effective defense mechanism. In C. batmchzls and H. fossilis club cells
are more or less equally abundant as mucous cells and are invariably large
in size, thus providing effective protection as well as defense. The defensive
function of the club cells has been established by Whitear and Mittal (1983),
Smith (1986) and Suzuki and Kaneko (1986). It is noteworthy that in Rita
rita epidermis, in which the mucous cells are very sniall and their overall
density very low, the club cells are observed in large numbers (Mittal, 1968).
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This condition is similar to the skin ofM. gzrlio in the present investigation.
Further Mittal et ul. (1976) observed that in Barbzrs sophor epidermis,in the
regions where the mucous cells are found in large numbers and enormously
developed, the club cells are either absent or are very few, where as in the
regions where mucous cells are few and smaller the club cells are well
developed and are present in appreciable numbers. But in C. batrach~rsand
H.jossilis both types of cells are abundant.
The mucous glands found in the epidermis of fishes investigated are
of various shapes and sizes. They are spherical as well as flask shaped in
Heteropnerrs/esjossilis and C l u r ~ batrachzrs.
s
According to Bertin (l95S),the
flask-shaped mucous cells situated in the outermost layer of the epidermis
principally develop from the cells of the basal layer. As they move towards
the outermost surface they become oval or round in shape and get filled with
mucus.Fina1ly they open directly outside and empty all the mucus at one
time. In H.jbssilis and C. burr~rchzrsthe flask-shaped and spherical mucous
nlands appear to be of same tvpe. It is possible that the spherical mucous
3
glands seen in the middle la!.ers of the epidermis are in different stages of
their migration towards the periphery and ultimately become flask-shaped
and open on the surface of the epidermis.
The large number of mucous cells in C. batrachus and
H.fossilis
suggests that the overall production of mucus in this fish is very high. This
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Inay be an adaptation to their peculiar bottom-scooping habit disturbing
bottom mud more frequently in search of food; requiring increased efficiency
in the fish keeping its surface clean; mucus has remarkable power to
precipitate mud held in suspension ( Hora, 1934). Thus the mucous secreted
by the skin in the air breathing fishes may also serve to keep the skin clear
for respiration.The abundance or dearth of the mucous cells in the epidermis
may also be correlated with their mode of life (Mittal and Banerjee, 1975).
Urawa (1992) suggested that epidermal mucus may contribute a protective
effect against pathogens. Mittal et al. (1994) Zander (1975) and Kotrschal
and Goldschmid (1983) suggested anti-viral, bactericidal and fungicidal effects
of the secretion. Chemical composition of the skin and its secretions have been
worked out by Al-Hassan et al. (1982,'1985, 1986, 1987) Ali, et al. (1987,
1989), Al-Lahham et al. (1987), Allen (1983), Belmeland et al. (1983) Harris et
al. (1973) and Summers et al. (1985, 1986) and found some role in defence and
wound healing. Clarias batrachzrs which is burrowing in habit and lives in
mud holes can survive for a considerable time out of water. It secretes copious
amount of mucus, lubricating heavily the surface of the body.This reduces
surface drag during burrowing and keeps the body surface wet, necessary
for cutaneous respiration.In contrast M. gzllio which is surface feeding and
where cutaneous respiration is not obvious, mucus production is less and
hence mucous cells are less abundant.
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It is interesting to note the presence of well defined lymphatic spaces
in the stratum germiantivum layer of the epidermis. These lymphatic spaces
are regularly arranged in between the cells of the stratum germinatvum and
are so small that only one or two small lymphocytes are able to move through
these spaces. Two functions may be assigned to this system of lymph spaces
of the epidermis, viz.,
1.
T h e supply of nutrients to the stratum germiantivum f o r cell
proliferation, and
2.
To protect the epiderm~sfrom micro-organisms or foreign proteins
(Bloom & Fawacett, 1968).
The relatively few lymphatic spaces and lymphocytes in M. gzrlio is
correlated with their habitat which is clear water containing comparatively
little pathogens than the muddy bottom.
The so-called spherical basal cells referred by Mittal (1968) and
blittal and Munshi (1970a) in the stratum germinativum layer of the epidermis
of Rita rlta and Bagnrlzrs bagarrs are nothing but lymphocytes. In wounded
skin these spaces increase in dimensions and literally become gorged with
lymphocytes (Mittal and Munshi, 1974).
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Eosinophilic granulocytes which were very common in the skin of
Rita rita (Mittal. 1968) could not be detected in the epidermis of the fishes
investigated.
Club cells were encountered in all the fishes investigated. Bertin
(1958) pointed out that these cells have derived their name as club cells
because in the first phase of their development they remain connected with
the basal membrane by a retractile peduncle. As they move towards the
surface of the epidermis they become pyriform and then oval. But studies on
the development of these cells in the skin of Rita rita (Mittal and Munshi,
1970 b) clearly show that even at their earliest phase of formation, they are
rounded and oval in shape and are not connected with the basal membrane
by retractile peduncles.
The sacciform glands reported by Mittal et al. (1980) in Monopterzrs
cuchia is not found in any of the fishes investigated.
The skin of C. batrach~rsis well vascularised in the dermis, it is less
in H. fossilis and very little in M. gulio. The extend of vascularisation of the
skin is also correlated with the habit of the organism. The well-vascularised
sltin of C. barrachlrs enable cutaneous respiration.
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Two distinct layers the stratum laxum and the stratum compactum,
may be distinguished in the dermis of C. batrachzrs and H. fossilis. such
s
1967), the
demarcation is feeble in M. gulio. In Monopterzis a i b ~ ~(Liem,
stratum laxum may further be divided into an outer papillary and an inner
reticular layer. No such differentiation is found in the fishes of the present
study, as there is no distinction for the presence of papille.
Earlier studies (van Oosten, 1957 ) revealed that there is an inverse
relationship between the thickness of the s t r a t u m compactum and
squamatum.Thus in the fishes of the present study where the scales are
entirely absent, the thickness of the stratum compactum is significantly
increased. In addition there is an increase in the thickness of the epidermis
and number of mucous cells and club cells; which also provide greater
protection as discussed earlier The compactly arranged collagen fibres in
the stratum compactum impart a leathery texture to the skin and protect the
body against stresses.
The pigment cells are confined to the dermal layers only. They are
more numerous in C. batrachlrs and H. fossilis, which live in the dark muddy
bottom, where the body colour merge with that of the substratum.
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Abbrevations used for figures in the thesis
Blood capillary
Basement membrane
CC
1,
.t
DER
Club cell
i
"7
OC
Dermis
Epithelial cells
EPD
Epidermis
GT
Granulation tissue
LC
Lymphocyte
MC
Mucous cell
MUS
Muscle
PG
Pigment cell
SC
Stratum compactunl
SCT
Subcutis
Stratum laxwn
Wound gap
Prepared by BeeHive Digital Concepts Cochin for Mahatma Gandhi University Kottayam
Fig. 5
Dorsal skin of Clarins bntrachus showing its laryers
Fig. 6
A psrt of the epidermis of Clarins batrach~rsshowing its cellular
components
Fig. 7
Dorsal skin of Heteropnez~stesfossilisshowing various layers
Fig. 8
A part of the epidermis of H. fossilis showing its cellular
components
Fig. 9
Dorsal skin of Mystus gzdio
Fig. 10
A part of the epidermis of M. gzilio showing its cellular
components
Scale
for fig. 5, 7, 9
Scale
for fig. 6, 8, 10
145P
32 P
Prepared by BeeHive Digital Concepts Cochin for Mahatma Gandhi University Kottayam
Prepared by BeeHive Digital Concepts Cochin for Mahatma Gandhi University Kottayam