Int. J. Aquat. Biol. (2016) 4(1): 17-24 

E-ISSN: 2322-5270; P-ISSN: 2383-0956

Journal homepage: www.ij-aquaticbiology.com 

© 2016 Iranian Society of Ichthyology 

Original Article 
A comparative study of the histoarchitecture of endocrine pancreas in Labeo bata (Hamilton, 

1822), Sperata aor (Hamilton, 1822) and Chitala chitala (Hamilton, 1822) 
 

Saroj Kumar Ghosh1, 2, Shrabani Barun1, 3, Padmanabha Chakrabarti*1 

 
1Fisheries Laboratory, Department of Zoology, The University of Burdwan, Burdwan-713104, West Bengal, India. 

2Department of Zoology, Bejoy Narayan Mahavidyalaya, Itachuna, Hooghly-712147, West Bengal, India. 
3Department of Zoology, Asansol Girls’ College, Asansol, Burdwan-713304, West Bengal, India.

 

 

 

 

 

 

 

 

 

Article history: 
Received 12 November 2015 

Accepted 6 January 2016 

Available online 2 5 February 2016 

Keywords:  
Histoarchitecture 

Endocrine pancreas 

Labeo bata 
Sperata aor 
Chitala chitala 

Abstract: The disposition and cellular organization of the endocrine pancreas were studied in three 
species of freshwater teleosts viz., Labeo bata (Hamilton, 1822), Sperata aor (Hamilton, 1822) and 

Chitala chitala (Hamilton, 1822) using histological techniques. In L. bata, the endocrine pancreas 

tissues were mainly distributed in the adipose tissue among the intestinal coils and adjacent to 

extrahepatic bile duct, while in S. aor and C. chitala, the endocrine pancreas predominantly attached 

with wall of the stomach along with exocrine pancreatic part. Histological analysis demonstrated that 

the endocrine components of all the three species were enclosed in a thin capsule provided with 

different cells, interspersed with blood sinuses. The cytoarchitectural analysis showed that in L. bata, 

β cells were usually arranged in groups while α cells were often interspersed with blood vessels. In 

S. aor and C. chitala, the rounded or oval α cells were usually arranged either in groups or scattered 

to the islets periphery and β cells which were densely granulated and typically stained with Aldehyde 

fuchsin (AF), Romies azan (RA) and Mallory’s triple (MT) were observed in the central areas of the 

islets and intercalated with blood vessels. The δ like cells were founded at a low frequency and 

intermingled with β cells and exhibited moderate cytoplasmic granules in L. bata, S. aor and 

C. chitala. Despite being the subject of extreme controversy, the nature and function of different islet 

cells were discussed. 
 

Introduction 

The endocrine pancreas present in different teleosts 

plays a momentous role in fish physiology. In fish, it 

exhibits various degrees of morphological, 

anatomical and cytological variations (Lazarow, 

1963; Kudo and Takahashi, 1973; Falkmer and 

Ostberg, 1977). Morphocytologically, the patterns of 

endocrine pancreas in fishes exhibits numerous 

species variations and quite often consists of several 

prominent knots of tissue, more or less segregated 

from the acinar parenchyma known as principal 

islets (Brinn and Epple, 1972). A compact terapod-

like organization of the pancreas with islets 

distributed throughout the exocrine parenchyma has 

been observed in Clarias batrachus (Khanna and 
Mehrotra, 1968), Mystus seenghala (Khanna and 

                                                           
* Corresponding author: Padmanabha Chakrabarti                                                                DOI: http://dx.doi.org/10.7508/ijab.2016.01.003 

E-mail address: dr.pchakrabarti@yahoo.in 

Gill, 1973) and Conger japonicas (Kobayashi and 
Takahashi, 1974).  

Tinctorial criteria, following granule staining and 

optical microscopic examination have usually been 

used for the identification of cells. Location of B and 

D cells tend to occupy the central part of the islet 

whereas the A and F cells are more numerous at the 

periphery. In Cottus scorpius and Channa punctatus, 
the B and D cells generally occupy central part of the 

islet whereas α and granular cells are mainly located 

at the periphery (Falkmer, 1961; Khanna and Singh, 

1971). In the goldfish Carassius carassius, B cells are 
usually arranged in groups or in cords which run 

irregularly or anastomose with each other to form a 

complicated network. The A and C cells are 

intermingled with these B cells cords of groups and  



18 
 

Ghosh et al./ Characterization of endocrine pancreas in L. bata, S. aor and C. chitala 

A cells often occur in small patches of few cells 

(Kobayashi and Takahashi, 1970). As regards the 

physiological role of the islet cells, ultimate proof 

have been obtained for the production of insulin by 

β cells in coho salmon, Oncorhynchus kisutch 
(Plisetskaya et al., 1985). The nature and function of 

A cell has been settled in favour of their being the 

source of glucagon in C. carassius (Kudo and 
Takahashi, 1973). Sayrafi et al. (2011) differentiated 

α and β cells by haematoxylin and eosin staining in 

the islets of Langerhans of Pangasius sanitwongsi. 
The aim of the present work is to characterize the 

cellular details and functional aspects of the 

endocrine pancreas in Labeo bata, Sperata aor and 
Chitala chitala having different feeding habits, by 
histological analysis. 

 

Materials and Methods 

Healthy fishes of L. bata (16.02±1.89 cm in total 
length; n=16), S. aor (31.35±2.43 cm in total length; 
n=12) and C. chitala (46.38±3.17 cm in total length; 
n=14) were collected from local freshwater fish farm 

of Burdwan (23.2333°N, 87.8667°E), West Bengal, 

India during February-August, 2015. Fishes were 

killed with an overdose of anesthetic (0.03% MS 

222; Tricaine methone-sulphonate, Sigma Chemical 

Co.) following the guidelines given by the 

Institutional Ethical Committee. 

For histological studies, the fishes were dissected 

and small pieces of the pancreas of S. aor and 
C. chitala and pancreatic tissues associated with 
adipose tissues among the intestinal coils of L. bata 
were removed and fixed in aqueous Bouin’s fluid for 

18 hrs. The tissues were then placed in 70% ethanol 

and subsequently dehydrated through the ascending 

series of ethanol, followed by acetone and cleared 

with xylene. Tissues were embedded in paraffin wax 

(56-58°C). Serial sections were cut at 4 µm 

thickness. Deparaffinized sections were brought to 

distilled water through descending series of ethanol 

and were stained with Delafield’s Haematoxylin-

Eosin (HE), Mallory’s triple (MT) (Mallory, 1936), 

Aldehyde fuchsin (AF) (Halami, 1952), and Romies 

azan (RA) stains. Sections were dehydrated through 

ascending series of ethanol, cleared in xylene, 

mounted in DPX, observed and photographed under 

LEICA EC3 compound microscope. 

 

Results 

The endocrine pancreas in L. bata (herbivore), S. aor 
(carnivore) and C. chitala (highly carnivore) exhibit 
a great deal of variations in relation to their 

occurrence as well as morpho-histological 

peculiarities. The endocrine pancreas in L. bata is 
associated with the adipose tissue located in between 

Figure 1. Endocrine pancreas in L. bata showing α cells at the 
periphery and β cells (arrow heads) in the central region. Arrow 

indicates blood vessel (MT, 100X). 

Figure 2. Acinar cells (AC) separated from islets of Langerhans by 

connective tissue septa (arrow heads) in L. bata. Note homogenous 
cytoplasm and deep nucleus in β cells (solid arrows) and deep 

nucleus in α cells (broken arrows). BV indicated blood vessels 

(MT, 1000X). 



19 
 

Int. J. Aquat. Biol. (2016) 4(1): 17-24 

 

coils of the intestine around the blood vessels and the 

bile duct within the mesentry. However, in S. aor and 
C. chitala, the pancreas is found to occur as a well-
developed compact organ situated in between the 

lobes of liver and seen to span from the border of the 

stomach to the anterior part of the intestine. The 

intrahepatic pancreatic tissue of hepatopancreas in 

L. bata is usually devoid of islets of Langerhans. 
Different cell types could be identified in the 

pancreatic islets, based mainly upon differences in 

the density of the cytoplasmic ground substance, in 

the shape and secretory granules. In L. bata, the 

pancreatic islet cells are separated from exocrine part 

by a thin capsule of connective tissue mainly of 

collagenous fibres. The distribution of α cells is 

restricted to the islet periphery facing towards acinar 

cells (Figs. 1, 2). The islet of α cells contained sparse 

cytoplasm and densely stained nucleus (Fig. 2). In 

the central portion of the islets the AF positive β cells 

exhibit rounded moderately dense cytoplasmic mass 

and direct contact with blood cells (Figs. 3, 4). 

Distinct granules of β cells are not seen in Mallory’s 

triple stain since the granules are soluble in ethanol. 

In S. aor, the pancreas is relatively more organized 

Figure 3. Showing α cells at the periphery (broken arrows) and 

inner β cells (solid arrows) adjacent to blood vessels (BV) and 

acinar cells (AC) in L. bata (RA, 400X). 

Figure 4. Endocrine pancreas in L. bata showing AF positive β 
cells, α cells (solid arrows) and vacuolated δ cells (broken arrows) 

encircling blood vessels (BV) (AF, 1000X). 

Figure 5. Comparatively light stained islet of Langerhans (IL) 

attached to the wall of the stomach (SW) and encircled by acinar 

cells (AC) in S. aor (HE, 100X). 

Figure 6. Scattered elongated islet of Langerhans (IL) positive to 

AF in between acinar cells (AC) and pancreatic duct (PD) in 

S. aor. Arrow heads indicate septa in between AC and IL (AF, 
400X). 



20 
 

Ghosh et al./ Characterization of endocrine pancreas in L. bata, S. aor and C. chitala 

in its structural architecture and patches of endocrine 

islets are surrounded by acinar cells (Figs. 5, 6). The 

rounded α cells are positive to Romies azan stain 

provided with conspicuous dense nucleus and 

homogenous cytoplasm which are situated at the 

surface of islets below the septa (Fig. 8) adjacent to 

blood vessels. The β cells are comparatively larger 

in size and ovoid in shape and clustered in the central 

portion of islets and are stained with Romies azan 

and Mallory’s triple stain (Figs. 7, 8). However, δ 

cells are solitary and few in number, provided with 

densely stained nuclei and scantly cytoplasm (Figs. 

7, 8). 

The small and large islet of Langerhans in C. 
chitala scattered as irregular elongated or oval 
masses of comparatively pale staining cells adjacent 

to rich blood vessels and acinar cells (Figs. 9, 10). α 

cells are at the periphery of the islet but occasional 

isolated cells may be found in its interior. β cells are 

numerous in the centre of the islets positive to AF 

having prominent nucleus and homogenous 

Figure 7. Islet of Langerhans (IL) separated from acinar cells (AC) 

by septa (arrow heads) in S. aor. Note peripheral α cells (solid 
arrows), intense red coloured β cells (broken arrows) and 

innermost δ cells adjacent to blood vessels (BV) (RA, 1000X). 

Figure 8. Islet of Langerhans (IL) in S. aor showing β cells with 
prominent nucleus and cytoplasm mass (broken arrows), α cells 

(solid arrows) and innermost δ cells in between acinar cells (AC). 

Arrow heads indicate septa (MT, 1000). 

Figure 9. Light stained small elongated or large oval islet 

Langerhans (IL) in C. chitala in between acinar cells (AC) and 
blood vessels (BV). Arrow heads indicate septa (RA, 150X). 

Figure 10. Higher magnification of islet Langerhans (IL) in 

C. chitala showing α cells at the periphery (solid arrows), β cells 
(broken arrows) and δ cells in central position. Arrow heads 

indicate septa in between IL and acinar cells (AC) (RA, 1000X). 



21 
 

Int. J. Aquat. Biol. (2016) 4(1): 17-24 

 

cytoplasm (Figs. 11, 12). Occasional isolated 

comparatively larger blue coloured agranular δ cells 

are scattered in between β cells (Fig. 10). 

 

Discussion 

In the present observation, the islet of Langerhans 

are dispersed throughout the pancreas in L. bata, 
S. aor and C. chitala. In all the fish species, the islet 
of Langerhans are enclosed in a thin capsule and 

consists of comparatively lightly stained fusiform 

cells with distinct nuclei and interspersed with blood 

sinuses. The endocrine portion of the L. bata is 
mainly distributed around intestinal bulb, intestine 

and bile duct. These descriptions resemble those 

given for islet aggregates in Salmoniformes (Wang 

et al., 1986). In S. aor and C. chitala, a number of 
lightly staining islet of Langerhans of different sizes 

and shapes occur in between exocrine acinar cells 

and around the pancreatic duct. Youson and Al-

Mahrouki (1999) considered the islet of Langerhans 

as principal islets of various sizes in fishes. They 

further opined that the intrahepatic pancreatic tissue 

is usually devoid of islets. 

In the present investigation in all the three fish 

species, the α cells are the most dominant cell types 

and most common on the periphery that appeared 

ovoid structure having oval nuclei and intense 

acidophilic cytoplasm. β cells are large in size, oval 

or rounded in shape with a granular or homogenous 

cytoplasm. On contrary, δ cells are solitary and few 

in number. Shyamsundari et al. (2006) reported that 

ovoid islets of Langerhans are usually with a central 

cluster of β cells and the α cells in the periphery in 

lizard fish Saurida tumbill. Mokhtar (2015) opined 
that the endocrine part of Ctenopharyngodon idella, 
the ovoid α cells are dominate, β cells are polyhedral 

and they grouped in small clusters while δ cells are 

small, fusiform and argyrophilic cells. Boquist and 

Patent (1971) by ultrastructural analysis noticed that 

in the islet of the teleost Scorpaena scropha the α 
cells are mostly abundant in the periphery of the 

islets and contained numerous secretory granules 

with electron dense core while β cells are central in 

position having medium sized rounded moderately 

dense secretory granules. In the present study, it has 

been observed that α, β and δ cells have contacts 

with the blood capillaries and sometimes the 

secretory contents of the cells are observed into the 

blood vessels. Therefore, it may be conjectured that 

after being secreted from the endocrine cells the 

hormones are carried out into the capillaries and 

thereby promoting movement of glucose. Iaglov 

(1978) emphasized that in C. carassius, Cyprinus 
carpio, Tinca tinca and Silurus glanis α, β and δ cells 

Figure 11. AF positive β cells (solid arrows), α cells (broken 

arrows) and fairly stained δ cells (arrow head) in the islet of 

Langerhans (IL) of C. chitala interspersed with blood vessels 
(BV). AC indicates acinar cells (AF, 600X). 

Figure 12. Higher magnification of AF positive β cells (solid 

arrows) adjacent to blood vessels (BV) in C. chitala. Note the 
presence of α cells (arrow heads) and solitary δ cell (broken arrow) 

(AF, 1000X). 



22 
 

Ghosh et al./ Characterization of endocrine pancreas in L. bata, S. aor and C. chitala 

are shoot shaped and all have contacts with the 

capillaries and the hormones from the endocrine 

cells is carried out via emiocytosis into the blood 

vessels. In the present investigation, in all the three 

fish species the most important hormones secreted 

by the islet of Langerhans are insulin from β cell and 

glucagon from α cells. Both play a role in proper 

metabolism of sugars and starches in the fish body. 

Insulin promotes the movement of glucose and other 

nutrients out of the blood and into cells. When blood 

glucose rises, insulin released from the β cells causes 

glucose to enter body cells to be used for energy. 

Also, it sometimes stimulates conversion of glucose 

to glycogen in the liver. Another hormone, glucagon 

from α cells promotes the movement of glucose into 

the blood when glucose levels are below normal. It 

causes the breakdown of stored liver glycogen to 

glucose, so that the sugar content of blood leaving 

the liver rises (Sorokin et al., 1982; Plisetskaya et al., 

1985; 1986). However, immunological analysis to 

endocrine cells of the aforesaid three species under 

study is further needed for detailed cellular structure 

and functions. 

 

Acknowledgements 

The authors are grateful to Dr. Sanjib Ray, Head of 

the Department of Zoology, The University of 

Burdwan, Burdwan for providing essential 

laboratory facilities. 

 

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Int. J. Aquat. Biol. (2016) 4(1): 17-24 

E-ISSN: 2322-5270; P-ISSN: 2383-0956

Journal homepage: www.ij-aquaticbiology.com 

© 2016 Iranian Society of Ichthyology 

 چکیده فارسی

 

 ی درون ریز پانکراس در ماهیانشناسی غدهای ساختار بافتمطالعه مقایسه

Labeo bata (Hamilton, 1822) ،Sperata aor (Hamilton, 1822)  وChitala chitala (Hamilton, 1822) 
  

 *1باراتیچ ، پادمانرا3 ،1شرابانی بارون ،2، 1کومار قوشساروج 

 .هندوستان غربی، بنگال ،411327 بوردوان بوردوان، دانشگاه جانورشناسی، گروه شیالت، مایشگاهآز1
 بنگال غربی، هندوستان. ، 232171 هوقلی ایتاچونا، ،بجوی نارایان ماهاویدیاالیا ،جانورشناسی گروه7

 بنگال غربی، هندوستان. ،214413 بوردوان ،آسانسول کالج دختران آسانسول، ،جانورشناسی گروه4

 

  چکیده:

 Labeo bata (Hamilton, 1822)، Sperata aorشامل شیرینریز پانکراس در سه گونه ماهی استخوانی آبی درونوضعیت و سازمان سلولی غده

(Hamilton, 1822) و Chitala chitala (Hamilton, 1822) شناسی مورد مطالعه قرار گرفت. در گونه های بافتتکنیکاستفاده از ا بL. bata 

ه در دو ک، در حالیدپراکنده شده بودن واقع در باالی پانکراسوی اصفر مجرایای نزدیک بین توده رودهعمدتاً در بافت چربی های غده پانکراس بافت

د کرد شناسی تائیریز پانکراس بود. تحلیل بافتبخش برونهمراه با به دیواره معده  چسبیده غالب طوربه غده پانکراس، C. chitalaو  S. aorگونه 
های خونی احاطه پراکنده شده در بین سینوسلف تهای مخلکه اجزای درون ریز هر سه گونه مورد مطالعه توسط یک کپسول نازک حاوی سلو

اغلب  αهای که سلولدر حالی داشتندصورت تجمعی آرایش به معموالً βهای سلول ،L. bataتحلیل ساختار سلولی نشان داد که در گونه شدند. می
صورت تجمعی یا پراکنده در به معموالً αهای گرد و بیضی شکل سلول C. chitalaو  S. aorهای. در گونهبودند های خونی واقع شدهبین رگ

های آلدئید فوشین، رومیز آزان و تریپل مالوری طور معمول با رنگکه بهمتراکم  مانند دانهدانه βهای ند و سلولشتاطراف جزایر النگرهانس آرایش دا

 تعداد اندک و آمیختهنیز به δهای شبیه های خونی مشاهده شدند. سلولو در اتصال با رگالنگرهانس ، در ناحیه میانی جزایر شوندمی یرنگ آمیز

نشان دادند. در ضمن در این مقاله  C. chitalaو  S. aorهایگونه های سیتوپالسمی میانه را درسیتوپالسمی یافت شدند و گرانول βهای سلولبا 

 مورد بحث قرار گرفت.  سهانرهای مختلف جزایر النگها، طبیعت و عملکرد سلولبه جای تاکید بیشتر بر تفاوت

 .Labeo bata ،Sperata aor ،Chitala chitalaی درون ریز پانکراس،ساختار بافتی، غده :کلمات کلیدی