The checker keel back is also known as Asiatic water snake and it is non venomous snake. The snake is endemic to Asia. They are limbless reptiles. They move their body by lateral undulation. The Assamese name of this snake is Dhora sap where as the Bengali name of this snake is Jol Dhora. The body of the snake is stout, with rounded pupils. The dorsum of the snake is olive brown along with black spots arranged in 5-6 rows. The head of the snake is brown with black strip from eye to upper lip. They are found in wetlands in plains like flooded rice fields, ponds, marshes and rivers. They are aquatic as well as active in day and night time. They eat fish and frogs which help in maintaining the water ecosystem[4]. Meagre reports are existing on the histo-morphological observation on the Skin, Liver, Spleen, and Kidney of the Checkered keel back (Xenochrophis piscator) of Assam when compared with other snakes; hence the present study was designed to establish an anatomical norm on these organs of the integument, digestive, immune and urinary system.

MATERIALS AND METHODS

The present study was conducted on the Skin, Liver, Spleen, and Kidney of Checkered keel back (Xenochrophis piscator) (Fig.1) of Assam in Department of Anatomy & Histology, College of Veterinary Science, Assam Agricultural University, Khanapara, Guwahati, Assam, India for a period of six months. The snake was died in road accident near Amchang wild life sanctuary when cross the road. After death, the snake was brought to the Department of Anatomy &Histology, College of Veterinary Science, Assam Agricultural University, Khanapra, Guwahati, Assam, India and then, the body cavity of the snake was open by mid ventral incision. After the opening of the body cavity of the snake, the tissue of skin, liver, spleen, and kidney were collected. After collection, the tissue samples were fixed in 10% neutral buffered formalin solution and were processed as per the standard technique of procedure [8]. The paraffin blocks were sectioned in Shandon Finesse microtome at 5µm thickness and the sections were stained with Mayer’s Haematoxylin and Eosin staining technique for Cellular details as per the standard method of [8].

RESULTS

 Histologically, the skin of the Checkered keel back (Xenochrophis piscator) was lined by keratinized stratified squamous epithelium. Numerous melanophores were observed in the upper part of the dermis layer of the skin (Fig.2). The liver of the snake was covered by the Glisson’s capsule (Fig.3). The capsule of the snake was very thin. The hilus of the liver of the Chkeelbackeel back (Xenochrophis piscator) of Assam contained cross-section of blood vessels (Fig.4). The central vein of the liver was surrounded by number of hepatic cords (Fig.5). The hepatic cords were formed by hepatocytes. Hepatic sinusoids were found among the hepatocytes. Among the hepatic cords, very fine trabeculae were observed. The hepatic lobule is not distinct. Fibrous bundle (Fig.7) and aggregation of lymphocytes (Fig.8) was observed in the cross-section of the liver of the snake. The portal traid of the liver was comp osed of hepatic artery, bile duct and hepatic vein (Fig.9). The bile ducts were lined by simple columnar epithelium. Melanin pigments were also found in the liver of the checkered keelback snake (Fig.6). In the present study, it was observed that the spleen of the snake was surrounded by a thin capsule (Fig.10). The hilus of the spleen contained cross-section artery (Fig.11). The red pulp and white pulp of the spleen was not distinct (Fig.12). Sheathed artery was observed in white pulp (Fig.13). Melano-macrophages were also observed among of the lymphocytes of the spleen (Fig.14). The trabeculae of the spleen were not distinct. The kidney of the Checkered keelback (Xenochrophis piscator) of Assam contained a distinct cortex and medulla (Fig.15), and cortico-medullary junction (Fig.16). The cortex contained numerous renal corpuscles and proximal and distal convoluted tubules. Capsular space, urinary pole, and macula densa were observed in the renal corpuscles (Fig.17). The diameter of proximal convoluted tubules was larger than the diameter of distal convoluted tubules.

DISCUSSIONS

Histologically, the skin of the Checkered keelback (Xenochrophis piscator) was lined by keratinized stratified squamous epithelium. Numerous melanophores were observed in the upper part of the dermis layer of the skin.  These findings were in accordance with the findings of [2] in limbless squamates. The liver of the snake was covered by the Glisson’s capsule. Similar findings were reported by [1] in King Cobra. The capsule of the snake was very thin. The hilus of the liver of the Checkered keelback (Xenochrophis piscator) of Assam contained cross-section of blood vessels. The central vein of the liver was surrounded by number of hepatic cords. The hepatic cords were formed by hepatocytes. Hepatic sinusoids were found among the hepatocytes. Among the hepatic cords, very fine trabeculae were observed. The hepatic lobule is not distinct. Fibrous bundle and aggregation of lymphocytes were observed in the cross-section of the liver of the snake. The portal triad of the liver was composed of the hepatic artery, bile duct, and hepatic vein. The bile ducts were lined by simple columnar epithelium. Similar observations were reported by [7] in the liver of King cobra. Melanin pigments were also found in the hepatocellular parenchyma of the liver of the checkered keelback snake. Similar findings were reported by [3] in the liver of reptiles, amphibians and fish. In the present study, it was observed that the spleen of the snake was surrounded by a thin capsule. The hilus of the spleen contained cross-section artery. The red pulp and white pulp of the spleen was not distinct. A sheathed artery was observed in white pulp. Melano macrophages were also observed among of the lymphocytes of spleen. These findings were in total agreement with the findings of [5] in Egyptian Nile Monitor Lizard. The trabeculae of the spleen were not distinct. The kidney of the Checkered keelback (Xenochrophis piscator) of Assam contained a distinct cortex and medulla, and cortico-medullary junction. The cortex contained numerous renal corpuscles and proximal and distal convoluted tubules. Capsular space, urinary pole and macula densa were observed in the renal corpuscles. The diameter of proximal convoluted tubules was larger than the diameter of distal convoluted tubules. These findings were in accordance with the findings of [6] in the kidney of the snake Eryx gaculus gaculus.

CONCLUSION

Thorough knowledge of the histology of the skin, liver, spleen and kidney of the Checkered keel back (Xenochrophis piscator) of Assam is very essential in elucidating its role in physiology, histopathology, endocrinology, and surgical anatomy.In the current investigation, it was observed thatthe skins of the Checkered keelback contain numerous melanophores. Fibrous bundles, aggregation of lymphocytes, melanin pigments, very thin trabeculae, hepatic cord, hepatic sinusoids were found in the liver of snake. The parenchyma of the spleen of the snake composed of red pulp and white pulp. The red pulp and white pulp was not distinct. A sheathed artery was observed in a white pulp. The red pulp contained red blood cells. The kidney of the checkered keelback was contained distinct cortex and medulla, and a cortico-medullary junction. Numerous renal corpuscles and proximal and distal convoluted tubules were observed in the cortex of the kidney of the snake. The diameter of proximal convoluted tubules is large than the distal convoluted tubules. These studies will be helpful to wildlife veterinarians for diseases control regimes and forensics science.

ACKNOWLEDGEMENT: The authors are grateful to the Dean, College of Veterinary Science, Assam Agricultural University, Khanapara, Assam, India for providing the required facilities to conduct this experiment.

REFERENCES

1. AhmedYA, Abdelsabor-KhalafM and MohammedE(2018)Histological insight into the hepatic tissue of the Nile monitor (Varanus  niloticus).Journal of Experimental and Applied Animal Science.2:240-250.
2. AllamAA,DazaJ.D and EleneenR.EA (2016)Histology of the skin of three limbless squamates dwelling in mesic and arid environments. The anatomical record.299:979-989.
3. Aughey E and Frye FL(2001)Comparative Veterinary Histology with clinical correlates. Manson Publishing Ltd, 73 Corringham Road, London NW117DL, UK, Edn.1st.Pp 124-125.
4. Das A and DasA(2018) A naturalist’s guide to the reptiles of Indian, Bangladesh ,Bhutan, Nepal, Pakistan and Sri Lanka,Praksh books,2^nd Edn.131p.
5. Mohammed ESI,MadkourFA and RadeyR(2021)Histological features of the spleen and pancreas of the Egyptian Nile Monitor Lizard (Varanus niloticus).International Journal of Veterinary Science.4(4):22-32.
6. ShuwailiEHA,AbedWB, FartusyARA and AbidAB(2017)Study of Histological structure of kidney in snake Eryx gaculus gaculus. International Journal Science and Research.6(4):860-863.
7. SonaP,MayaS,ZiyaAM,AnnieVR,LucyKM,SreeranjiniAR, InduVR, SumenKB and SunilkumarNS(2020)Histomorphological overlook of liver in King Cobra (Ophiophagus hannah).Journal of Indian Veterinary Association.18(3):52-56.
8. Luna LG (1968) Manuals of histological staining methods of Armed forces institute of Pathology, 3^rd edn. Mc Graw Hill Book Co., London.

Fig.1: Photograph showing theCheckered keel back (Xenochrophis piscator)(A) of Assam.

Fig.2:Photomicrograph showing the keratinized stratified squamous epithelium (A) and melanophages (B) of skin of Checkered keel back (Xenochrophis piscator) of Assam.

Fig.3: Photomicrograph showing the Glisson’s capsule (Arrow) of liver of Checkered keel back (Xenochrophis piscator) of Assam.

Fig.4: Photomicrograph showing the hilus (A) of liver of Checkered keel back (Xenochrophis piscator) of Assam.

Fig.5: Photomicrograph showing the central vein (A) of liver of Checkered keel back (Xenochrophis piscator) of Assam.

Fig.6: Photomicrograph showing the melanin pigment (Arrow) of liver of Checkered keel back (Xenochrophis piscator) of Assam.

Fig.7: Photomicrograph showing the fibrous bundle (Arrow) of liver of Checkered keel back (Xenochrophis piscator) of Assam.

Fig.8: Photomicrograph showing the aggregation of lymphocytes (A) of liver of Checkered keel back (Xenochrophis piscator) of Assam.

Fig.9: Photomicrograph showing the bile duct (A), hepatic vein (B), hepatic artery (C) and hepatic cord (D) of liver of Checkered keel back (Xenochrophis piscator) of Assam.

Fig.10: Photomicrograph showing the capsule (Arrow) of spleen of Checkered keel back (Xenochrophis piscator) of Assam.

Fig.11: Photomicrograph showing the hilus (A) and artery (Arrow) of spleen of Checkered keel back (Xenochrophis piscator) of Assam.

Fig.12: Photomicrograph showing the white pulp (A) and red pulp (B) of spleen of Checkered keel back (Xenochrophis piscator) of Assam.

Fig.13: Photomicrograph showing the white pulp (A) and sheathed artery (B) of white pulp of spleen of Checkered keel back (Xenochrophis piscator) of Assam.

Fig.14: Photomicrograph showing the Melano macrophages (Arrow)of spleen of Checkered keel back (Xenochrophis piscator) of Assam.

Fig.15: Photomicrograph showing the cortico-medullary junction (A) of kidney of Checkered keel back (Xenochrophis piscator) of Assam.

Fig.16: Photomicrograph showing the cortex (A) and medulla (B) of kidney of Checkered keel back (Xenochrophis piscator) of Assam.

Fig.17: Photomicrograph showing the renal corpuscle (A), capsular space (B), urinary pole (C), proximal convoluted tubules (D), distal convoluted tubules (E) and macula densa (F)  of kidney of Checkered keel back (Xenochrophis piscator) of Assam.