Gross morphology, morphometry and histomorphology of the adrenal gland in lactating and non-lactating Kosali cow

Introduction

Livestock play an important role in the agricultural and rural economy of India by providing milk, manure, draught power and employment to farming communities. India possesses a rich diversity of livestock genetic resources with nearly forty recognized breeds of cattle. In the state of Chhattisgarh, livestock rearing is an integral component of the mixed farming system and is closely associated with the socio-economic and cultural life of rural people (Jain et al., 2018) [1] . Kosali cattle represent the first registered indigenous breed of Chhattisgarh and have been recognized as the 36th cattle breed of India (Accession No. INDIA CATTLE 2600 KOSALI 03036). The breed derives its name from "Kowshal," the ancient name of the central region of Chhattisgarh. Kosali cattle have evolved over generations under the local agro-climatic conditions and are known for their heat tolerance, adaptability and resistance to diseases (Jain et al., 2017) [2] . They are mainly distributed in the Central Plain Region of the state, covering about 68.49 lakh hectares across fifteen districts, with an estimated population of about 31.32 lakh animals (Jain et al., 2018) [1] . The breed is traditionally maintained by farming communities such as the Yadava and Rawuth. Endocrine glands play a vital role in regulating various physiological processes through the secretion of hormones directly into the bloodstream. These hormones regulate metabolism, growth, reproduction and maintenance of homeostasis in animals (Kumar et al., 2018) [3] . Among these glands, the adrenal glands are of particular importance as they produce hormones essential for metabolic regulation, stress response and electrolyte balance. The adrenal cortex secretes mineralocorticoids, glucocorticoids and androgens, which regulate electrolyte balance, carbohydrate metabolism and protein metabolism, respectively, while the adrenal medulla produces catecholamines such as adrenaline and noradrenaline that influence cardiovascular activity and stress adaptation (Hullinger and Andrisani, 2006 [4] ; Greco and Stabenfeld, 2007 [5] ). These hormones are closely associated with physiological processes such as parturition, lactation and stress response in farm animals. Considering the economic importance of Kosali cattle and the vital physiological role of adrenal hormones in productivity and metabolic regulation, the present study was undertaken to investigate the gross anatomical and histoarchitectural features of the adrenal glands in Kosali cattle.

Materials and methods

The present study was conducted on adrenal glands of twelve Kosali cows. Samples were collected from freshly dead Kosali cows from Rajnandgaon, Durg and Balod, districts of Chhattisgarh. Animals were divided into lactating and nonlactating groups. The adrenal glands were collected in 10% neutral buffered formalin. Biometrical parameters were recorded. The tissue samples were processed and stained by routine method. Micrometry of stained section was done with the help of Labovision KXi2000 photomicroscope. Obtained parameters were statistically analyzed as per standard statistical method.

Results and Discussion

Gross morphology

Right and left adrenal glands were located retroperitoneally in abdominal cavity, however, Barszcz et al. (2016) [6] have reported location of adrenal glands is intraperitoneally in European bison. In present study right adrenal gland was located at the level of 10-11 intercostal space, 9-10 cm below the transverse process of thoracic vertebrae on right side of median plane and 1-2 cm cranial to the right kidney. Right adrenal gland was anteriorly covered by caudate lobe of the liver. Right adrenal gland was laterally flattened, heart shaped gland having two surface and three borders viz. dorsal, ventral and caudal with cranial pointed apex. Lateral surface was related with cranial extremity of right kidney. Lateral surface was related to caudal vena cava marked by a groove at the middle of this surface. The medial surface of the right adrenal gland was convex and in close apposition with the right crus of the diaphragm. Dorsal border was longest and related with caudate lobe of liver. Ventral border was shortest and related with posterior vena cava. Present topographical findings corroborated the observations of Konig and Liebich (2004) [7] , Ye et al. (2017) [8] and Sharma (2019) [9] . Left adrenal gland was roughly comma or C-shaped, situated at 5-6 cm anterior to cranial pole of the left kidney and its long axis was directed cranially and ventrally. It was located at the level of 11 th to 12 th intercostal space and 12-13 cm below the transverse process of thoracic vertebrae. It had two extremities, two borders and two surfaces. Right surface was related to beginning of jejunum coil and left surface was attached with dorsal sac of rumen. Dorsal border was placed along the caudal vena cava and was convex, also related with beginning of left renal vessels. Ventral border was notched. The position of notch varied from cranial third to caudal third and it was of variable depth. Cranial extremity was conical shaped and bluntly pointed. Caudal extremity was rectangular, broad and flattened. Hilus was present on right surface at cranioventral part. However Left adrenal gland was C-shaped in Jaffarabadi buffalo (Sharma et al., 2020) [10] , V-shaped in Nili Ravi buffalo (Hussain et al., 2006) [11] , and oval shaped in camel by Abubakar (2015) [12] . Topographical findings were similar to previous observations of Venzke (1975) [13] in ruminants and Sharma (2019) [9] in Jaffarabadi buffaloes. The topographic position and shape of adrenal gland did not show any distinguishable differences during lactating and nonlactating stage, However Joshi (2016) [14] and Sharma (2019) [9] reported seasonal effect in position, shape, colour and topography of the adrenal glands in goats and buffalo respectively. The mean weight of right and left adrenal of non-lactating Kosali cow was 5.26 ± 0.29 and 5.78 ± 0.42 gm respectively, while lactating group showed higher and nonsignificant value viz. 6.42 ± 0.51 and 8.05 ± 0.44 in right and left adrenal respectively. Volume also showed higher value in lactating stage than in non-lactating stage. The recorded weight and volume of left adrenal gland were comparatively higher than right adrenal gland in both the groups. The present study supports the findings of Venzke (1975) [13] in cattle and Ye et al. (2017) [8] in Bactrian camel. However Sharma (2019) [9] reported that the weight of both adrenal glands was maximum during rainy season in comparison to summer and winter. Recorded length of right adrenal gland was significantly higher in lactating stage than non-lactating stage. The ratio of length between lactating and non-lactating stage was 2.50: 3.0. Whereas, the length in lactating stage was higher in decimal value in left adrenal gland and was not significant. Recorded length of left adrenal gland was more than right adrenal gland. While length of right and left adrenal gland was 6.69 ± 0.09 cm. and as6.85 ± 0.10 cm respectively in Nili Ravi buffalo (Hussain et al., 2006) [11] . Sharma (2019) [9] reported slightly shorter right adrenal gland than the left in Jaffarabadi buffalo. Recorded width of right adrenal gland was maximum at caudal end and it was 2.93 ± 0.23 cm. for non-lactating and 3.20 ± 0.58 for lactating group. While width of left adrenal gland was maximum at middle and it was 2.33 ± 0.10 cm. and 2.60 ± 0.18 cm. for non-lactating and lactating group respectively. Cranial width of lactating Kosali cow was significant. The borders of right (dorsal, ventral and caudal) and left (dorsal and ventral) adrenal gland was longer in lactating stage and was non-significant. Perimeter of right adrenal gland was significantly higher in lactating stage whereas it was non-significant for left adrenal gland. Left and right adrenal glands were thickest at mid region in both the groups. Maximum thickness of the left adrenal gland was 1.08 ± 0.09 cm for non-lactating and 1.14 ± 0.05 cm. for lactating left adrenal gland. Maximum thickness of right adrenal gland was 1.16 ± 0.04 cm. and 1.18 ± 0.04 cm. for non-lactating and lactating stage respectively. Cranial thickness of right adrenal gland was significantly higher in lactating stage than in non-lactating stage. Right adrenal gland was thicker than left adrenal gland in both groups. Present findings are supported by the report of Ye et al.

(2017) [8] in Bactrian camel and Sharma (2019) [9] in Jaffarabadi buffalo. The values of cross sectional area of right and left adrenal gland were non-significant and higher in lactating stage. It was maximum in right adrenal gland of lactating stage followed by non-lactating right adrenal, lactating left adrenal and non-lactating left adrenal gland.

Histomorphology

Histoarchitectural organization of the gland consisted of peripheral large cortex and small inner medulla, which was similar to the previous description of to the adrenal gland of Kuehnel (2003) [15] , Hullinger and Andrisani 2006 and Ye et al. (2017) [8] . Adrenal cortex was divided into three zones on the basis of morphology of cells, their arrangement and the staining characteristics as outermost narrow zona glomerulosa, intermediate zona fasciculata and zona reticularis was similar to the findings of Barszcz et al.

(2016) [6] in European bison and Sharma (2019) [9] in Jaffrabadi buffalo. In contrast to the present findings, an additional zona intermedia was reported between zona glomerulosa and zona fasiculata by Hullinger and Andrisani (2006) [6] and Ye et al. (2017) [8] .The adrenal cortex constituted the outer largest part of the adrenal glands. Thickness of capsule was minimum (20.17 ± 1.78μm) in non-lactating left adrenal gland and maximum (33.17 ± 6.36μm) in left lactating adrenal gland and it was nonsignificant in both right as well as in left adrenal gland. The outer adrenal cortex surrounded the medulla. Cortical thickness was higher than medullary thickness. Cortical thickness in non-lactating left adrenal gland was minimum (712.00 ± 77.01μm) and maximum in lactating left adrenal gland (1016.17 ± 133.04μm). The recorded cortical thickness was non-significant. Present recorded thickness was less than the findings of Sharma (2019) [9] in Jaffarabadi buffalo. Cells of zona glomerulosa varied from round oval to polyhedral shape and arranged in irregular manner. The nuclei of the zona glomerulosa cells were deeply stained which supported the findings of Kuehnel (2003) [15] . Recorded thickness of zona glomerulosa was more in lactating stage and non-significant. It was minimum in right adrenal gland in non-lactating stage and maximum in left adrenal gland lactating stage. The cells of widest zonezona fasciculata were cuboidal with lighter nuclei than zona glomerulosa. The cells were mostly arranged in columns with one cell thick. In some places cells were present in the form of round aggregations. Recorded thickness of zona fasciculata was higher in lactating adrenal gland and was maximum in lactating left adrenal gland. The polyhedral cells of zona reticularis were arranged in anastomosing cords and formed irregular network support the findings of Kuehnel (2003) [15] and Hullinger and Andrisani, (2006) [4] . No significant difference in thickness of zona reticularis was observed in both the glands in present study. The cells of the medulla were large dark polyhedral shaped in outer layer and smaller lighter in inner lighter layer. The cells were granular in appearance. The large ganglionic cell with colloid was apparently observed. Trabecular and muscular veins were seen. Apparently no remarkable differences were observed in histoarchitecture of lactating and non-lactating Kosali cows. Histoarchitectural findings were similar to the previous observations of medulla by Barszcz et al. (2016) [6] , Ye et al. (2017) [8] and Sharma (2019) [9] . Thickness of medulla was more in lactating stage than non-lactating stage in right as well as in left adrenal gland. Recorded medullary thickness was minimum in nonlactating left adrenal gland and maximum in left lactating adrenal gland.

Conclusion

The present study provides a detailed account of the gross morphology, morphometry and histomorphology of the adrenal glands in lactating and non-lactating Kosali cows. Both adrenal glands were located retroperitoneally in the abdominal cavity and exhibited distinct asymmetry in shape and position. The right adrenal gland was heart-shaped and situated slightly cranial to the right kidney, whereas the left adrenal gland was comma or C-shaped and positioned cranially to the left kidney with its long axis directed cranioventrally. The topographical relationships of the glands with adjacent organs such as the liver, rumen, caudal vena cava and kidneys were consistent with earlier reports in ruminants. No marked differences in the position or general morphology of the adrenal glands were observed between lactating and non-lactating cows. Morphometrical observations revealed comparatively higher weight, volume and dimensions of adrenal glands in the lactating stage, although most parameters showed nonsignificant differences. The left adrenal gland generally exhibited greater weight and length, whereas the right gland was relatively thicker. Histologically, the adrenal gland consisted of an outer cortex and inner medulla. The cortex was differentiated into zona glomerulosa, zona fasciculata and zona reticularis with typical cellular arrangement.

Although cortical and medullary thickness tended to be higher during lactation, the overall histoarchitecture remained similar in both physiological stages. Thus, the adrenal glands of Kosali cows demonstrate typical ruminant morphology with minor morphometric variations during lactation, while maintaining a consistent structural organization.

References

1. Jain A, Barwa DK, Singh M, Mukherjee K, Jain T, Tantia MS, et al. Physical characteristics of Kosali breed of cattle in its native tract. Indian J Anim Sci. 2018;88(12):1362-1365.
2. Jain A, Barwa DK, Jain T, Singh M, Mukherjee K, Gendley MK. Geographical distribution, management practices and utility of Kosali cattle at native tract. Int J Sci Environ. 2017;6(6):3420-3426.
3. Kumar D, Vaish R, Pandey Y, Gupta N, Umeel, Kumar P. Thyroid gland: an anatomical perspective. J Entomol Zool Stud. 2018;6(4):1400-1405.
4. Hullinger RL, Andrisani OM. Endocrine system. In: Eurell JAC, Frappier BL, Dellmann HD, editors. Dellmann's textbook of veterinary histology. 6th ed. Ames: Blackwell Publishing; 2006. p. 298-319.
5. Greco DS, Stabenfeld GH. Endocrine glands and their function. In: Cunningham JG, Klein BG, editors. Textbook of veterinary physiology. 4th ed. St. Louis: Saunders; 2007. p. 428-464.
6. Barszcz K, Przespolewska H, Olbrych K, Czopowicz M, Kleckowska-Nawrot J, Gozdziewska-Harłajczuk K, et al. The morphology of the adrenal gland in the European bison (Bison bonasus). BMC Vet Res. 2016;12:161.
7. Konig HE, Liebich HG. Endocrine glands. In: Veterinary anatomy of domestic mammals: textbook and colour atlas. 4th ed. Stuttgart: Schattauer; 2004. p. 537-545.
8. Ye WL, Wang FL, Wang HJ, Wang JL. Morphology and ultrastructure of the adrenal gland in Bactrian camels (Camelus bactrianus). Tissue Cell. 2017;49:285-295.
9. Sharma A. Gross morphological, histological and histochemical studies on pineal, pituitary, thyroid and adrenal glands of Jaffarabadi buffalo during different seasons of the year [PhD thesis]. Junagadh: Junagadh Agricultural University; 2019.
10. Sharma A, Vyas YL, Kumar V, Tank PH, Talekar SH. Gross morphometric studies on thyroid and adrenal glands of Jaffarabadi buffalo during different seasons of the year. Indian J Vet Anat. 2020;32(1):19-22.
11. Hussain R, Qureshi AS, Shahid RU, Rahman SU. Age related changes in the morphometric parameters of the heart, kidneys and adrenal glands of Nili-Ravi buffalo. Pak Vet J. 2006;26(2):59-62.
12. Zaria: Ahmadu Bello University; 2015.
13. Venzke WG. Endocrine glands. In: Getty R, editor. Sisson and Grossman's the anatomy of the domestic animals. Vol. 1. 5th ed. Madras: Macmillan India Press; 1975. p. 955-959.
14. Joshi S. Gross and histological studies on the thyroid gland of goat (Capra hircus) [PhD thesis]. Bikaner: Rajasthan University of Veterinary and Animal Sciences; 2016.
15. Kuehnel W. Endocrine glands. In: Colour atlas of cytology, histology and microscopic anatomy. 4th ed. Stuttgart: Thieme; 2003. p. 254-271.