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Full Research Article

Age-wise Cellular Identification and Morphometry of the Endocrine Pancreas in Post-hatched Ducks

A
Anil Kumar Safi1
M
Manoj Kumar Sinha1
A
Avnish Kumar Gautam1,*
0000-0002-5696-3856
S
Sudhanshu Kumar1
1Department of Veterinary Anatomy, Bihar Veterinary College, Bihar Animal Sciences University, Patna-800 014, Bihar, India.

ABSTRACT

Background: The pancreas is a vital gland with both exocrine and endocrine functions and its structural organization varies among avian species and during postnatal development. Understanding the age-related histological organization of the pancreatic endocrine tissue in ducks is essential for establishing baseline morphological data and for comparative anatomical studies.

Methods: A total of forty ducks were procured from a certified duck farm and divided into four age-based groups, with ten birds in each group: post-hatched (Group I), one month old (Group II), three months old (Group III) and six months old (Group IV). Pancreatic samples, including the dorsal, ventral and splenic lobes, were processed for routine histological examination. Gomori’s staining technique was employed for the identification and differentiation of endocrine cell types within the pancreas.

Result: Histological examination revealed that the dorsal, ventral and splenic lobes of the pancreas exhibited a similar structural organization across all age groups. In all groups, the pancreatic parenchyma consisted predominantly of exocrine tissue, with a relatively small proportion of endocrine tissue. The endocrine component was embedded within the exocrine tissue and appeared as the islets of langerhans, which were irregularly distributed throughout the exocrine portion of each pancreatic lobe. Using Gomori’s staining technique, three distinct types of pancreatic islets were identified: alpha islets, beta islets and mixed islets.

INTRODUCTION

Ducks (Anatidae) are widely distributed waterfowl adapted to diverse ecological habitats worldwide. The popularity of duck is increasing in many areas of the world as ducks are one of the most versatile and useful of all domesticated animals and birds (Deka, 2024). In recent years, they have gained importance as an alternative poultry species due to their high-quality meat and eggs, adaptability and disease resistance (Pingel, 2011).  Ducks have innate potential to produce eggs and meat at considerable quantity with lesser input and they are a good dietary source of proteins (Veeramani, 2023 and Kalita, 2023). Consequently, detailed anatomical and histological studies of ducks have become increasingly relevant.
       
The avian digestive system exhibits marked structural and functional specializations in comparison to mammals, reflecting unique feeding habits and metabolic demands (King and McLelland, 1984). Among avian visceral organs, the pancreas plays a crucial role in digestion and carbohydrate metabolism through its dual exocrine and endocrine functions and is located within the duodenal loop (Dellmann and Eurell, 1998). In birds, the pancreas is composed of dorsal, ventral and splenic lobes, each showing distinct histological organization (Nickel et al., 1977). The exocrine portion produces digestive enzymes, whereas the endocrine component, represented by the Islets of Langerhans, regulates glucose homeostasis through hormones such as insulin and glucagon (Banks, 1993). Due to its specialized functions, even minor structural alterations may adversely affect pancreatic activity.Despite its physiological importance, detailed histological and histochemical information on the pancreatic lobes of ducks at different post-hatching stages remains limited. Therefore, the present study was undertaken to elucidate the microscopic architecture and histochemical characteristics of the pancreatic lobes in ducks, with particular emphasis on the distribution and identification of endocrine components.

MATERIALS AND METHODS

The present investigation was conducted during the year 2024-25 in the Department of Veterinary Anatomy, Bihar Veterinary College, Patna, on pancreatic samples collected from forty ducks of both sexes procured from a registered duck farm. The birds were divided into four age-based groups, with ten ducks in each group. Group I comprised newly hatched ducklings, Group II included ducks aged one month, Group III consisted of ducks aged three months and Group IV comprised ducks aged six months. Immediately after collection, the pancreas along with its respective lobes (dorsal, ventral and splenic) was carefully excised, washed thoroughly in normal saline to remove blood and debris and fixed in 10% buffered neutral formalin for histological examination. After adequate fixation, tissue samples from each lobe were processed routinely through paraffin embedding. Serial sections of appropriate thickness were cut and stained with Haematoxylin and Eosin (Luna, 1968) for general histoarchitecture. In addition, special staining techniques were employed to demonstrate specific tissue components, including Gomori’s stain, Masson’s trichrome stain (Bancroft and Stevens, 1996) and Toludine blue (Luna, 1968). Micrometric measurements were performed wherever necessary using an ocular micrometer. The data obtained were subjected to statistical analysis and interpreted according to the standard procedures described by Snedecor and Cochran (1994).

RESULTS AND DISCUSSION

General histomorphology of pancreas
 
The current study discovered that the dorsal, ventral and splenic lobes of the duck pancreas had the same histological composition across all age groups. Each pancreatic lobe was found to be made up of three parts: the capsule, the exocrine section and the endocrine part.
 
Endocrine
 
Based on the present findings, the parenchyma of the pancreatic lobes in ducks of all age groups contained only a small endocrine component. The endocrine areas, embedded within the exocrine tissue, were identified as the islets of langerhans. These islets were found to be irregularly distributed throughout the exocrine portion of each pancreatic lobe. Variation in the size and shape of the islets was also noted in the ducks examined (Fig 1). The findings of the present study were consistent with the observations reported by Abou-Zaid et al. (2010) in pigeons; Saadatfar et al., (2011) in palm doves; Hamodi et al. (2013) in guinea fowls and common gulls; Mobini (2013) in pigeons; Al-Sharoot (2016) in geese; and Suresh (2018) in Japanese quail. These researchers similarly described endocrine islets of varying sizes and shapes distributed within the exocrine portion of the pancreas.

Fig 1: Photomicrograph showing oval in oval marked area and spherical form in rectangular marked area of endocrine portion of pancreas of group II. (Gomori’s trichrome, ×100).


       
In the current investigation, the endocrine component of the pancreas was occasionally observed in group I of experimental ducks. However, in group II and onward, the endocrine part was commonly observed. The study also found that in all experimental ducks, the splenic lobe of the pancreas had a higher occurrence of islets than the dorsal and ventral lobes of the pancreas. The current findings were somewhat consistent with those of Yadav et al., (2018) in chabro chicken, Tomita et al., (1985) in chickens, Parchami and Kusha (2015) in native chicken and Smith (1974) in Coturnix quail.

Islets of langerhans
 
In the present study, Gomori’s pancreatic islet staining demonstrated the presence of three types of pancreatic islets in the experimental ducks: alpha, beta and mixed islets (Fig 2). Alpha islets were found to have a higher concentration of alpha cells and fewer beta cells and these cells stained light pink to light red. Beta islets were found to have a higher concentration of beta cells and fewer alpha cells and these cells stained purple to blue, whereas mixed islets contained both types of alpha and beta cells. In keeping with current findings, Saadatfar and Asadian (2009) discovered in Mynah that there were alpha cells,  delta cells and a few beta cells inside the alpha islets. Additionally, there were a few delta cells in the beta islets but no alpha cells. Alpha cells showed red staining, while beta cells showed blue staining from Gomori’s stain. According to Madhavi et al., (2000b), ducks possess alpha and beta islets, which are predominantly composed of alpha and beta cells, respectively, along with a few delta cells in each type of islet. They also observed that Gomori’s Chrome-Alum Hematoxylin stained alpha cells red to pink after application, but beta cells stained blue after receiving the same treatment. Suresh, (2018) in Japanese quail found reddish in colour for alpha cells with Gomori’s method and stained reddish blue to bluish in colour for beta cells.

Fig 2: Photomicrograph showing different alpha islets (B) and beta islets (A) of endocrine portion of pancreas of group IV. (Gomori’s method ×100).


       
In all age groups of experimental ducks, the mean diameter of islets in all pancreatic lobes were recorded and found as 187.39±8.73 µm, 324.55±11.69 µm, 385.67±6.45 µm and 479.95±16.65 µm in dorsal lobe pancreas of ducks in group I, II, III and IV respectively (Fig 3 and Table 1). In ventral lobe of pancreas, it was 128.83±7.12 µm, 251.88±8.77 µm 281.05±13.92 µm and 346.87±4.88 µm in group I, II, III and IV respectively, on other hand in splenic lobe the diameter of islets were measured as 301.09±7.12 µm, 456.83±8.77 µm, 575.66±13.92 µm and 597.87±4.88 µm respectively in group I, II, III and IV (Fig 4-5 and Table 1). As the age of the experimental ducks progressed, it was noticed that the mean diameter of the islets in all of the pancreatic lobes increased (p<0.05). In dorsal lobe significant change was noticed in group I and IV. In ventral lobe significant change was observed in group I, II and IV. In splenic lobe of pancreas significant changes were observed in between group I and III and in group II and IV. Yadav et al., (2018) obtained average islets diameters of 41.42±2.77 μm, 35.89±2.44 μm and 54.87±3.31 μm in the dorsal, ventral and splenic lobes, respectively, in chabro chicken, which was consistent with the results of our investigation. Mahmood et al., (2022) in native ducks recorded average diameter of islets as 55.55±11.12 μm, 74.75±5.03 μm and 86.47±6.02 μm in dorsal, ventral and third lobe of pancreas respectively. These values were less than the present observations; it may be due to species variation.

Table 1: Showing mean diameter of islets, alpha cells and beta cells in different lobes of duck pancreas (µm).



Fig 3: Photomicrograph showing diameter of islets of dorsal lobe of pancreas of group IV. (Gomori’s method ×400).



Fig 4: Photomicrograph showing diameter of islets of ventral lobe of pancreas of group II. (Masson’s trichrome method ×100).



Fig 5: Photomicrograph showing diameter of islets of splenic lobe of pancreas of group IV. (Gomori’s method ×400).


 
Alpha cells
 
The current study discovered alpha cells in the endocrine section of the pancreatic lobes in all experimental ducks, regardless of age. The alpha cells were observed to be mostly columnar to elongate in form, with one or two discrete nucleoli (Fig 6 and 7). These findings were somewhat compatible with those reported by Madhavi et al., (2000b) in ducks, Rajendran et al., (2010) in emu, Das et al., (2003) in ducks and Suresh (2018) in Japanese quail.

Fig 6: Photomicrograph showing alpha cells (arrow) and beta cells (zigzag arrow) of dorsal lobe of pancreas of group II. (Gomori’s method ×1000).



Fig 7: Photomicrograph showing alpha cells (arrow) and beta cells (zigzag arrow) of pancreas of group IV. (Toluidine blue ×400).


       
Under present experiment, the mean diameters of alpha cells were recorded in all pancreatic lobes of all experimental ducks. The present findings for mean diameter of alpha cells in dorsal lobe were 66.93±1.51 μm, 72.49±1.31 μm, 79.01±1.83 μm and 84.1±3.02 μm for group I, II, III, IV respectively (Fig 8 and Table 1). The mean diameter of alpha cells in ventral lobe of pancreas was 69.95±0.82 μm, 76.84±2.10 μm, 85.42±2.21 μm and 86.88±4.09 μm in group I, II, III, IV respectively (Table 1). However, in splenic lobe of pancreas it was 72.69±1.42 μm, 80.51±1.73 μm, 91.24±1.38 μm and 95.02±4.28 μm in group I, II, III, IV respectively (Fig 9 and Table 1). The findings of the current observation revealed that the average diameter of alpha cells was found to be increased with the advancement of age(p<0.05). In dorsal lobe significant change was noticed in group I and IV. In ventral lobe significant change was observed in group I and II. In splenic lobe of pancreas significant changes were observed in between group I and III and in group II and IV. In support of present findings Madhavi et al., (2000a), documented the average alpha cell diameter in local ducks was 100±0.59 μm, 114.33±5.4 μm and 138±4.2 ìm in dorsal, ventral and splenic lobes respectively.

Fig 8: Photomicrograph showing diameter of alpha and beta cells of dorsal lobe of pancreas of group III. (Gomori’s method ×1000).



Fig 9: Photomicrograph showing diameter of alpha and beta cells of splenic lobe of pancreas of group IV. (Hematoxylin and eosin ×1000).


 
Beta cells
 
According to the current study’s findings, beta cells were found in the endocrine component of every pancreatic lobe in all experimental duck age groups. The current results revealed that the bulk of beta cells were polygonal to oval in shape (Fig 10). The nucleus of beta cells was identified using numerous stained slides. The results of the current investigation show that beta cells have one to two nuclei in their cytoplasm.The present studies were in accordance with descriptive of Hussein and Bargooth (2022) in ducks that beta cells were mostly spherical, occasionally rectangular in form. Rajendran et al., (2010) found that beta cells in emu had a polygonal morphology. In ducks, Das et al., (2003) found that the beta cells had a rounded, oval, or ellipsoidal form. The nucleus of ducks was spherical to ovoid with one or two nucleoli and the beta cells were polygonal, according to Madhavi et al., (2000b).

Fig 10: Photomicrograph showing polygonal to oval form of beta cells of pancreas. (Gomori’s method ×400).


       
The mean diameters of all the pancreatic lobes’ beta cells were measured in experimental ducks of all ages. The mean diameter of beta cells in the dorsal lobe was determined to be 38.81±1.07 μm in group I, 41.90±0.52 μm in group II, 43.99±0.89 μm in group III and 45.81±0.77 μm in group IV under the current investigation (Fig 8 and Table 1). The mean diameter of beta cell in the pancreatic ventral lobe was 39.05±1.13 μm for group I, 43.35±0.62 μm, 45.26±0.78 μm and 48.12±1.44 μm for groups II, III and IV, respectively (Table 1). However, the mean diameter of beta cells in the splenic lobe was 40.27±0.91ìm in group I, 48.13±0.95 μm in group II, 55.41±1.14 μm in group III and 58.43±1.35 μm in group IV (Fig 9 and Table 1). 
       
In local ducks, Madhavi et al., (2000) measured the beta cells in the dorsal, ventral and splenic lobes of the pancreas to be 44.6±6.3 μm, 62.66±1.85 μm and 67±5.4 μm, respectively in support of present findings. The average diameter of the beta cells in the pancreatic islets increased with age, according to the current study (p<0.05). In dorsal lobe significant change was noticed in group I and IV. In ventral and splenic lobe significant change was observed in group I, II and III.

CONCLUSION

The study of the duck pancreas across various age groups revealed a consistent histological structure in the dorsal, ventral and splenic lobes. Each lobe featured a thin fibrous capsule containing collagen and some elastic fibres, with the exocrine portion being predominant. Endocrine components appeared as small islets scattered within the exocrine tissue. Gomori’s staining identified three islet types: alpha, beta and mixed, with islet size increasing with age. Alpha cells, characterized by their columnar to elongated shape and one or two nuclei, were present in all ducks, as were oval or polygonal beta cells with distinct nuclei. The mean diameters of both cell types increased as the ducks aged.

ACKNOWLEDGEMENT

The present study was supported by Bihar Animal Sciences University, Patna.
 
Disclaimers
 
The views and conclusions expressed in this article are solely those of the authors and do not necessarily represent the views of their affiliated institutions. The authors are responsible for the accuracy and completeness of the information provided, but do not accept any liability for any direct or indirect losses resulting from the use of this content.
 
Informed consent
 
All ducks procured for experiments were approved by the Committee of Experimental Animal Care and Handling techniques were approved by the University of Animal Care Committee.

CONFLICT OF INTEREST

The authors declare that there are no conflicts of interest regarding the publication of this article. No funding or sponsorship influenced the design of the study, data collection, analysis, decision to publish, or preparation of the manuscript.

REFERENCES


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  2. Al-Sharoot, H.A. (2016). Anatomical, histological and histochemical architecture of pancreases in early hatched goose (Anser anser). Kufa Journal of Veterinary Medical Sciences. 7(1): 147-153.

  3. Bancroft, J.D. and Stevens, A. (1996). Theory and Practice of Histological Techniques. Churchill Livingstone, New York.

  4. Banks, W.J. (1993). Applied Veterinary Histology. 3rd Edn., Mosby- Year Book, St. Louis, Missouri.

  5. Das, A., Das, R.K., Parida, S., Mishra, U.K. and Solank D. (2003). Histomorphological study on pancreas of duck (Anas boscas). Indian Journal of Animal Sciences. 73: 598- 599.

  6. Deka A., Talukdar M. and Talukdar D.J. (2024). Histochemical studies on post natal development of gut associated lymphoid tissue (GALT) of intestine of pati duck (Anas platyrhynchos domesticus) of Assam. Indian Journal of Animal Research. 58(6): 978-981. doi: 10.18805/IJAR.B-4533.

  7. Dellmann, H.D. and Eurell, J.A. (1998). Textbook of Veterinary Histology. 5th Edn., Lippincott Williams and Wilkins, Baltimore.

  8. Hamodi, H.M., Abed, A.A. and Ameer, M.T. (2013). Comparative anatomical, histological and histochemical study of the pancreas in two species of birds. Research and reviews in Bioscience. 8(1): 26-34.

  9. Hussein, A.A. and Bargooth, A.F. (2022). Histological and immunohistochemical study of the endocrine pancreas of duck (Anas platyrhnchos). International Journal of Health Sciences. 6(S6): 7962-7973.

  10. Kalita, K., Rajkhowa, J., Sarma, K., Talukdar, M. and Sinha, S. (2023). Gross morphological, histological and histochemical studies on liver of pati ducks (Anas platyrhynchos domesticus) of Assam. Indian Journal of Animal Research. doi: 10.18805/IJAR.B-5095.

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  13. Madhavi, G., Rao, T.S.C., Kumar, P.D., Nagamalleswari, Y. and Sreenu, M. (2000a). Histological studies on the exocrine portion of pancreas of the domestic duck (Anas boschasdomesticus). Indian Journal Animal Science. 70(2): 126-128.

  14. Madhavi, G., Rao, T.S.C., Kumar, P.D., Nagamalleswari, Y. and Sreenu, M. (2000b). Histological studies on the endocrine portion of pancreas of the domestic duck (Anas boschasdomesticus). Indian Journal Animal Science. 70(2): 129-132.

  15. Mahmood, S.K., Ahmed, N.S., Sultan, G.A. and Yousif, M.J. (2022). Histomorphological and carbohydrate histochemical study of the pancreas in native ducks (Anas platyrhynchos). Iraqi Journal of Veterinary Sciences. 36(4): 1103-1110.

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  22. Saadatfar, Z., Asadian, M. and Alishahi, E. (2011). Structure of pancreas in palam dove (Streptoplia selegalensis). Iranian Journal of Veterinary Science and Technology. 3(2): 25-32.  

  23. Smith, P.H. (1974). Pancreatic islets of the coturnix quail. A light and electron microscopic study with special reference to the islet organ of the splenic lobe. Anatomical Record. 178: 567-585. 

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    Full Research Article

    Age-wise Cellular Identification and Morphometry of the Endocrine Pancreas in Post-hatched Ducks

    A
    Anil Kumar Safi1
    M
    Manoj Kumar Sinha1
    A
    Avnish Kumar Gautam1,*
    0000-0002-5696-3856
    S
    Sudhanshu Kumar1
    1Department of Veterinary Anatomy, Bihar Veterinary College, Bihar Animal Sciences University, Patna-800 014, Bihar, India.

    ABSTRACT

    Background: The pancreas is a vital gland with both exocrine and endocrine functions and its structural organization varies among avian species and during postnatal development. Understanding the age-related histological organization of the pancreatic endocrine tissue in ducks is essential for establishing baseline morphological data and for comparative anatomical studies.

    Methods: A total of forty ducks were procured from a certified duck farm and divided into four age-based groups, with ten birds in each group: post-hatched (Group I), one month old (Group II), three months old (Group III) and six months old (Group IV). Pancreatic samples, including the dorsal, ventral and splenic lobes, were processed for routine histological examination. Gomori’s staining technique was employed for the identification and differentiation of endocrine cell types within the pancreas.

    Result: Histological examination revealed that the dorsal, ventral and splenic lobes of the pancreas exhibited a similar structural organization across all age groups. In all groups, the pancreatic parenchyma consisted predominantly of exocrine tissue, with a relatively small proportion of endocrine tissue. The endocrine component was embedded within the exocrine tissue and appeared as the islets of langerhans, which were irregularly distributed throughout the exocrine portion of each pancreatic lobe. Using Gomori’s staining technique, three distinct types of pancreatic islets were identified: alpha islets, beta islets and mixed islets.

    INTRODUCTION

    Ducks (Anatidae) are widely distributed waterfowl adapted to diverse ecological habitats worldwide. The popularity of duck is increasing in many areas of the world as ducks are one of the most versatile and useful of all domesticated animals and birds (Deka, 2024). In recent years, they have gained importance as an alternative poultry species due to their high-quality meat and eggs, adaptability and disease resistance (Pingel, 2011).  Ducks have innate potential to produce eggs and meat at considerable quantity with lesser input and they are a good dietary source of proteins (Veeramani, 2023 and Kalita, 2023). Consequently, detailed anatomical and histological studies of ducks have become increasingly relevant.
           
    The avian digestive system exhibits marked structural and functional specializations in comparison to mammals, reflecting unique feeding habits and metabolic demands (King and McLelland, 1984). Among avian visceral organs, the pancreas plays a crucial role in digestion and carbohydrate metabolism through its dual exocrine and endocrine functions and is located within the duodenal loop (Dellmann and Eurell, 1998). In birds, the pancreas is composed of dorsal, ventral and splenic lobes, each showing distinct histological organization (Nickel et al., 1977). The exocrine portion produces digestive enzymes, whereas the endocrine component, represented by the Islets of Langerhans, regulates glucose homeostasis through hormones such as insulin and glucagon (Banks, 1993). Due to its specialized functions, even minor structural alterations may adversely affect pancreatic activity.Despite its physiological importance, detailed histological and histochemical information on the pancreatic lobes of ducks at different post-hatching stages remains limited. Therefore, the present study was undertaken to elucidate the microscopic architecture and histochemical characteristics of the pancreatic lobes in ducks, with particular emphasis on the distribution and identification of endocrine components.

    MATERIALS AND METHODS

    The present investigation was conducted during the year 2024-25 in the Department of Veterinary Anatomy, Bihar Veterinary College, Patna, on pancreatic samples collected from forty ducks of both sexes procured from a registered duck farm. The birds were divided into four age-based groups, with ten ducks in each group. Group I comprised newly hatched ducklings, Group II included ducks aged one month, Group III consisted of ducks aged three months and Group IV comprised ducks aged six months. Immediately after collection, the pancreas along with its respective lobes (dorsal, ventral and splenic) was carefully excised, washed thoroughly in normal saline to remove blood and debris and fixed in 10% buffered neutral formalin for histological examination. After adequate fixation, tissue samples from each lobe were processed routinely through paraffin embedding. Serial sections of appropriate thickness were cut and stained with Haematoxylin and Eosin (Luna, 1968) for general histoarchitecture. In addition, special staining techniques were employed to demonstrate specific tissue components, including Gomori’s stain, Masson’s trichrome stain (Bancroft and Stevens, 1996) and Toludine blue (Luna, 1968). Micrometric measurements were performed wherever necessary using an ocular micrometer. The data obtained were subjected to statistical analysis and interpreted according to the standard procedures described by Snedecor and Cochran (1994).

    RESULTS AND DISCUSSION

    General histomorphology of pancreas
     
    The current study discovered that the dorsal, ventral and splenic lobes of the duck pancreas had the same histological composition across all age groups. Each pancreatic lobe was found to be made up of three parts: the capsule, the exocrine section and the endocrine part.
     
    Endocrine
     
    Based on the present findings, the parenchyma of the pancreatic lobes in ducks of all age groups contained only a small endocrine component. The endocrine areas, embedded within the exocrine tissue, were identified as the islets of langerhans. These islets were found to be irregularly distributed throughout the exocrine portion of each pancreatic lobe. Variation in the size and shape of the islets was also noted in the ducks examined (Fig 1). The findings of the present study were consistent with the observations reported by Abou-Zaid et al. (2010) in pigeons; Saadatfar et al., (2011) in palm doves; Hamodi et al. (2013) in guinea fowls and common gulls; Mobini (2013) in pigeons; Al-Sharoot (2016) in geese; and Suresh (2018) in Japanese quail. These researchers similarly described endocrine islets of varying sizes and shapes distributed within the exocrine portion of the pancreas.

    Fig 1: Photomicrograph showing oval in oval marked area and spherical form in rectangular marked area of endocrine portion of pancreas of group II. (Gomori’s trichrome, ×100).


           
    In the current investigation, the endocrine component of the pancreas was occasionally observed in group I of experimental ducks. However, in group II and onward, the endocrine part was commonly observed. The study also found that in all experimental ducks, the splenic lobe of the pancreas had a higher occurrence of islets than the dorsal and ventral lobes of the pancreas. The current findings were somewhat consistent with those of Yadav et al., (2018) in chabro chicken, Tomita et al., (1985) in chickens, Parchami and Kusha (2015) in native chicken and Smith (1974) in Coturnix quail.

    Islets of langerhans
     
    In the present study, Gomori’s pancreatic islet staining demonstrated the presence of three types of pancreatic islets in the experimental ducks: alpha, beta and mixed islets (Fig 2). Alpha islets were found to have a higher concentration of alpha cells and fewer beta cells and these cells stained light pink to light red. Beta islets were found to have a higher concentration of beta cells and fewer alpha cells and these cells stained purple to blue, whereas mixed islets contained both types of alpha and beta cells. In keeping with current findings, Saadatfar and Asadian (2009) discovered in Mynah that there were alpha cells,  delta cells and a few beta cells inside the alpha islets. Additionally, there were a few delta cells in the beta islets but no alpha cells. Alpha cells showed red staining, while beta cells showed blue staining from Gomori’s stain. According to Madhavi et al., (2000b), ducks possess alpha and beta islets, which are predominantly composed of alpha and beta cells, respectively, along with a few delta cells in each type of islet. They also observed that Gomori’s Chrome-Alum Hematoxylin stained alpha cells red to pink after application, but beta cells stained blue after receiving the same treatment. Suresh, (2018) in Japanese quail found reddish in colour for alpha cells with Gomori’s method and stained reddish blue to bluish in colour for beta cells.

    Fig 2: Photomicrograph showing different alpha islets (B) and beta islets (A) of endocrine portion of pancreas of group IV. (Gomori’s method ×100).


           
    In all age groups of experimental ducks, the mean diameter of islets in all pancreatic lobes were recorded and found as 187.39±8.73 µm, 324.55±11.69 µm, 385.67±6.45 µm and 479.95±16.65 µm in dorsal lobe pancreas of ducks in group I, II, III and IV respectively (Fig 3 and Table 1). In ventral lobe of pancreas, it was 128.83±7.12 µm, 251.88±8.77 µm 281.05±13.92 µm and 346.87±4.88 µm in group I, II, III and IV respectively, on other hand in splenic lobe the diameter of islets were measured as 301.09±7.12 µm, 456.83±8.77 µm, 575.66±13.92 µm and 597.87±4.88 µm respectively in group I, II, III and IV (Fig 4-5 and Table 1). As the age of the experimental ducks progressed, it was noticed that the mean diameter of the islets in all of the pancreatic lobes increased (p<0.05). In dorsal lobe significant change was noticed in group I and IV. In ventral lobe significant change was observed in group I, II and IV. In splenic lobe of pancreas significant changes were observed in between group I and III and in group II and IV. Yadav et al., (2018) obtained average islets diameters of 41.42±2.77 μm, 35.89±2.44 μm and 54.87±3.31 μm in the dorsal, ventral and splenic lobes, respectively, in chabro chicken, which was consistent with the results of our investigation. Mahmood et al., (2022) in native ducks recorded average diameter of islets as 55.55±11.12 μm, 74.75±5.03 μm and 86.47±6.02 μm in dorsal, ventral and third lobe of pancreas respectively. These values were less than the present observations; it may be due to species variation.

    Table 1: Showing mean diameter of islets, alpha cells and beta cells in different lobes of duck pancreas (µm).



    Fig 3: Photomicrograph showing diameter of islets of dorsal lobe of pancreas of group IV. (Gomori’s method ×400).



    Fig 4: Photomicrograph showing diameter of islets of ventral lobe of pancreas of group II. (Masson’s trichrome method ×100).



    Fig 5: Photomicrograph showing diameter of islets of splenic lobe of pancreas of group IV. (Gomori’s method ×400).


     
    Alpha cells
     
    The current study discovered alpha cells in the endocrine section of the pancreatic lobes in all experimental ducks, regardless of age. The alpha cells were observed to be mostly columnar to elongate in form, with one or two discrete nucleoli (Fig 6 and 7). These findings were somewhat compatible with those reported by Madhavi et al., (2000b) in ducks, Rajendran et al., (2010) in emu, Das et al., (2003) in ducks and Suresh (2018) in Japanese quail.

    Fig 6: Photomicrograph showing alpha cells (arrow) and beta cells (zigzag arrow) of dorsal lobe of pancreas of group II. (Gomori’s method ×1000).



    Fig 7: Photomicrograph showing alpha cells (arrow) and beta cells (zigzag arrow) of pancreas of group IV. (Toluidine blue ×400).


           
    Under present experiment, the mean diameters of alpha cells were recorded in all pancreatic lobes of all experimental ducks. The present findings for mean diameter of alpha cells in dorsal lobe were 66.93±1.51 μm, 72.49±1.31 μm, 79.01±1.83 μm and 84.1±3.02 μm for group I, II, III, IV respectively (Fig 8 and Table 1). The mean diameter of alpha cells in ventral lobe of pancreas was 69.95±0.82 μm, 76.84±2.10 μm, 85.42±2.21 μm and 86.88±4.09 μm in group I, II, III, IV respectively (Table 1). However, in splenic lobe of pancreas it was 72.69±1.42 μm, 80.51±1.73 μm, 91.24±1.38 μm and 95.02±4.28 μm in group I, II, III, IV respectively (Fig 9 and Table 1). The findings of the current observation revealed that the average diameter of alpha cells was found to be increased with the advancement of age(p<0.05). In dorsal lobe significant change was noticed in group I and IV. In ventral lobe significant change was observed in group I and II. In splenic lobe of pancreas significant changes were observed in between group I and III and in group II and IV. In support of present findings Madhavi et al., (2000a), documented the average alpha cell diameter in local ducks was 100±0.59 μm, 114.33±5.4 μm and 138±4.2 ìm in dorsal, ventral and splenic lobes respectively.

    Fig 8: Photomicrograph showing diameter of alpha and beta cells of dorsal lobe of pancreas of group III. (Gomori’s method ×1000).



    Fig 9: Photomicrograph showing diameter of alpha and beta cells of splenic lobe of pancreas of group IV. (Hematoxylin and eosin ×1000).


     
    Beta cells
     
    According to the current study’s findings, beta cells were found in the endocrine component of every pancreatic lobe in all experimental duck age groups. The current results revealed that the bulk of beta cells were polygonal to oval in shape (Fig 10). The nucleus of beta cells was identified using numerous stained slides. The results of the current investigation show that beta cells have one to two nuclei in their cytoplasm.The present studies were in accordance with descriptive of Hussein and Bargooth (2022) in ducks that beta cells were mostly spherical, occasionally rectangular in form. Rajendran et al., (2010) found that beta cells in emu had a polygonal morphology. In ducks, Das et al., (2003) found that the beta cells had a rounded, oval, or ellipsoidal form. The nucleus of ducks was spherical to ovoid with one or two nucleoli and the beta cells were polygonal, according to Madhavi et al., (2000b).

    Fig 10: Photomicrograph showing polygonal to oval form of beta cells of pancreas. (Gomori’s method ×400).


           
    The mean diameters of all the pancreatic lobes’ beta cells were measured in experimental ducks of all ages. The mean diameter of beta cells in the dorsal lobe was determined to be 38.81±1.07 μm in group I, 41.90±0.52 μm in group II, 43.99±0.89 μm in group III and 45.81±0.77 μm in group IV under the current investigation (Fig 8 and Table 1). The mean diameter of beta cell in the pancreatic ventral lobe was 39.05±1.13 μm for group I, 43.35±0.62 μm, 45.26±0.78 μm and 48.12±1.44 μm for groups II, III and IV, respectively (Table 1). However, the mean diameter of beta cells in the splenic lobe was 40.27±0.91ìm in group I, 48.13±0.95 μm in group II, 55.41±1.14 μm in group III and 58.43±1.35 μm in group IV (Fig 9 and Table 1). 
           
    In local ducks, Madhavi et al., (2000) measured the beta cells in the dorsal, ventral and splenic lobes of the pancreas to be 44.6±6.3 μm, 62.66±1.85 μm and 67±5.4 μm, respectively in support of present findings. The average diameter of the beta cells in the pancreatic islets increased with age, according to the current study (p<0.05). In dorsal lobe significant change was noticed in group I and IV. In ventral and splenic lobe significant change was observed in group I, II and III.

    CONCLUSION

    The study of the duck pancreas across various age groups revealed a consistent histological structure in the dorsal, ventral and splenic lobes. Each lobe featured a thin fibrous capsule containing collagen and some elastic fibres, with the exocrine portion being predominant. Endocrine components appeared as small islets scattered within the exocrine tissue. Gomori’s staining identified three islet types: alpha, beta and mixed, with islet size increasing with age. Alpha cells, characterized by their columnar to elongated shape and one or two nuclei, were present in all ducks, as were oval or polygonal beta cells with distinct nuclei. The mean diameters of both cell types increased as the ducks aged.

    ACKNOWLEDGEMENT

    The present study was supported by Bihar Animal Sciences University, Patna.
     
    Disclaimers
     
    The views and conclusions expressed in this article are solely those of the authors and do not necessarily represent the views of their affiliated institutions. The authors are responsible for the accuracy and completeness of the information provided, but do not accept any liability for any direct or indirect losses resulting from the use of this content.
     
    Informed consent
     
    All ducks procured for experiments were approved by the Committee of Experimental Animal Care and Handling techniques were approved by the University of Animal Care Committee.

    CONFLICT OF INTEREST

    The authors declare that there are no conflicts of interest regarding the publication of this article. No funding or sponsorship influenced the design of the study, data collection, analysis, decision to publish, or preparation of the manuscript.

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