Comparative morphological and morphometrically study of the adrenal gland in adult males' squirrel (Sciurus anomalous) and hamster (Mesocricetus auratus)

Article Highlights

1. A significant difference between the left and right adrenal glands in both animals,
2. Found that the right and left squirrel glands are larger, heavier, longer, and thicker than the adrenal gland in hamsters after the following measures were adopted: weight, length, thickness, width, and size.
3. Histologically, the cortex containing contains three zones in both animals.

Comparative morphological and morphometrically study of the adrenal gland in adult males' squirrel (Sciurus anomalous) and hamster (Mesocricetus auratus)

Abdulrazzaq B kadhim and Iman M Khaleel

1Department of Anatomy and Histology, College of Veterinary Medicine, University of Al-Qadisiyah, Al-Qadisiyah, 2Department of Anatomy, College of Veterinary Medicine, University of Baghdad, Baghdad, Iraq

[email protected], https://orcid.org/0000-0001-6356-4223

[email protected], https://orcid.org/0000-0001-6038-1608

Abstract

Given the physiological significance and the need for further physiological and morphological knowledge of the adrenal glands, the objectives of the current study were to compare morphometric data between the right and left adrenals of male squirrels and hamsters. The study was conducted on five squirrel males and five hamster males. The glands in both animals were removed and fixed in neutral formalin solution. It was found that the squirrel contains two brown-colored right and left adrenal glands connected anteriorly and medially to each cranial pole of the kidney, and the right adrenal gland had a longitudinal shape, while the left gland had an oval shape. Hamsters had two pairs of brown adrenal glands located anteriorly attached to each kidney's cranial pole. The right adrenal gland was round in shape, while the left was oval. The statistical results showed a significant difference between the left and right suitable adrenal glands in both animals, as well as a significant difference between the squirrel gland and the hamster gland, where it was found that the right and left squirrel glands are larger more significant, heavier, longer and thicker than the adrenal gland in hamsters after the following measures were adopted: weight, length, thickness, width, and size.

Keyword: Squirrel, Hamsters, Morphology, Adrenal gland

مقارنة مورفولوجیا ومورفومتریة للغدة الکظریة بین ذکور السناجب البالغة وذکور الهامستر البالغة

عبد الرزاق باقر کاظم و إیمان موسى خلیل

1فرع التشریح والأنسجة، کلیة الطب البیطری، جامعة القادسیة، 2فرع التشریح والانسجة، کلیة الطب البیطری، جامعة بغداد، العراق

الخلاصة

نظرًا للأهمیة الفسیولوجیة والحاجة إلى مزید من المعرفة الفسیولوجیة والمورفولوجیا لِلغدد الکظریة، کانت أهداف الدراسة الحالیة هی مقارنة البیانات الشکلیة بین الغدة الکظریة الیمنى والیسرى لذکر السنجاب والهامستر. أجریت الدراسة على خمسة ذکور سنجاب وخمسة ذکور هامستر. تمت إزالة الغدد فی کلا الحیوانین وتثبیتها فی محلول فورمالین متعادل. وجد أن السنجاب یحتوی على غدتین من الغدد الکظریة الیمنى والیسرى بلون بنی متصلین من الأمام والوسط بکل قطب قحفی للکلیة، والغدة الکظریة الیمنى لها شکل طولی، بینما کان للغدة الیسرى شکل بیضاوی. کان للهامستر زوجان من الغدد الکظریة البنیة الموجودة من الأمام متصلة بکل قطب قحفی من الکلیة، وکانت الغدة الکظریة الیمنى مستدیرة الشکل، بینما کان الیسار بیضاوی الشکل. أظهرت النتائج الإحصائیة وجود فرق معنوی بین الغدد الکظریة الیمنى والیسرى فی کلا الحیوانین، بالإضافة إلى اختلاف معنوی بین غدة السنجاب وغدة الهامستر، حیث وجد أن غدد السنجاب الیمنى والیسرى أکبر وأثقل وأطول. وأسمک من الغدة الکظریة فی الهامستر بعد اتخاذ التدابیر التالیة: الوزن، والطول، والسماکة، والعرض والحجم.

Introduction

Rodents are the largest mammal species number, accounting for more than 40% of all mammal species. Rodent biology has become an area of increasing research interest. This may be attributed to their use as a ready source of animal protein, experimental animals, and zoonotic diseases (1). The Caucasian squirrel or Persian squirrel (Sciurus anomalous) belongs to Rodent and genus Sciurus. It is found in forests of the Middle East and extreme southwestern Asia. Persian squirrel is a medium-sizedrodentweighing 200 to 410 g (2,3). The golden or Syrian hamster (Mesocricetus auratus) is a rodent that belongs to the subfamily, Cricetinae. Their natural geographical areas are northern Syria and southern Turkey. The body mass ranges between 100-125 g (4) inch the metabolic rate to about 5% and help the animal stress resistance. Therefore, used in laboratory typical research, especially pharmacological audition of skin and sensitiveness (5,6). Adrenal glands are compound endocrine glands that play a key crucial role in the secretion of chemical substance substances and many types of hormones that help metabolism, fluid and electrolyte balance, and maintenance of life. Structurally, they are comprised of the cortex and medulla (7-9). This work was designed to investigate the morphological characteristics and morphometrically measurements of the adrenal gland in males Squirrel and Hamster and comparing compare between them, to provide information that could lead to improved knowledge of the adrenal glands of the two animals and to provide a baseline data on the adrenal gland of these animals.

Up to date, there are no available studies in the previous and present literature investigations to the adrenal gland squirrel and hamsters According to this reason and the importance of this animal's species mentioned in the above introduction, the project will be conducted to the morphological structure and morphometrically measurements of Adrenal gland in Adult Males Squirrel (Sciurus anomalus) and Hamster (Mesocricetus auratus), and comparison between them.

Materials and Methods

The current study was carried out on ten male Squirrels and Hamsters. After recording the live body weight, the rodents were sacrificed, and the topography and relationship of adrenal glands were recorded. The anatomical parameters of adrenal glands, such as each gland's weight, volume, length, and diameter, were recorded and listed in tables. The statistical analysis was carried out using (t-test) for the methods suggested of comparison of parametric variances of the adrenal glands between Squirrel and Hamsters and the significance level was at P˂0.05 (25).

Results

This study showed that the anatomical findings of the adrenal gland in squirrel and hamsters were paired small glands; left and right, both were situated retroperitoneal in the abdominal cavity. Generally, they were situated on each side of the vertebral column and resting on the superior poles of the corresponding kidney (Figures 1 and 2). In squirrel, the right adrenal was located cranio medial side of the right kidney and enclosed by the caudate lobe of the liver close to the right proper aspect of the aorta and more cranial than the left one (Figures 1 and 3), whereas the left adrenal located to the left side of the abdominal aorta on the anterior pole of the left kidney and related to the stomach greater curvature (Figures 1 and 3).

In the hamster, the right and left adrenal were embedded in the adipose tissue, and the right gland was slightly different in its location than the right one of squirrel, it had a convex dorsal surface that fits over the craniomedial surface (more medially than of squirrel) of the right kidney and close to the hilus of the right kidney (Figure 2) it's covered by the liver (Fig 4), while the left adrenal rested on the left kidney cranial pole and is more cranially than the right one (Figure 2). In both squirrel and hamster, the adrenal gland was attached to the cranial pole of the corresponding kidney,

In squirrels, the right adrenal was more cranial than the left one (Figures 1 and 3), Whereas in hamsters, the left adrenal gland was located cranially than the right one (Figure 2). In squirrels, the external feature of the right adrenal gland showed a more elongated or (elliptical like) shape than the left one, which has a (bean-like) shape and brownish color (Figure 5), in hamsters, the right adrenal appeared elongated oval to (egg-like) shape, while the left gland displays more rounded (Figure 6).

The right and left adrenal glands in both squirrels and hamster showed soft, crusty, and dark brownish color (Figures 5 and 6), and each of them contains a yellowish outer region which represents the cortex, and the inner dark reddish-brown region represent represents the medulla (Figures 7 and 8),

Figure 1: The gross anatomy of the adrenal glands in adult male Squirrel Shows: Right adrenal gland (yellow star) Left adrenal gland (green star) Right kidney (RK), Left kidney (LK).

Figure 2: The gross anatomy of adrenal glands in hamster Shows: Right adrenal gland (yellow arrow) Left adrenal gland (green arrow) Right kidney (RK), Left kidney (LK).

Figure 3: Location of the adrenal glands in squirrel Shows: Right adrenal gland (yellow star) Left adrenal gland (green star), Right kidney RK, Left kidney LK, Liver (L), Stomach (ST), Spleen (S), pancreas (P) and renal vein (red arrow).

Figure 4: The gross anatomy of adrenal glands in hamster Shows: Left adrenal gland (green star) Right kidney (RK), Left kidney (LK), Liver(L), Stomach (ST), Spleen (S).

Figure 5: The gross anatomy (external feature) of adrenal glands in squirrel Shows: Right adrenal gland(R), Left adrenal gland (L).

Figure 6: The gross external feature adrenal glands of hamster Shows: Right Adrenal gland (R), Left adrenal gland (L).

Figure 7: The gross anatomy (internal feature) adrenal glands of squirrel Show: Capsule (red arrow), Cortex (yellow arrow), and medulla (blue arrow).

Figure 8: The gross anatomy (internal feature) adrenal glands of hamster Shows: Capsule (yellow arrow), cortex (red arrow), and medulla (green star).

Anatomical measurements of the adrenal gland in squirrel and hamster

The mean average squirrel and hamster weight, mean total adrenal weight, mean relative weight, mean total volume was listed in (Table 1). The statistical analysis revealed that mean of these measurements was higher significantly at (P>0.05) in squirrels than those of hamsters (Table 1). These differences may be due to species variations. In squirrel, the mean weight, length, width, thickness, volume values of the right and left adrenal gland were listed (Table 2). The statistical analysis of results displays that the mean of these measurements of the right adrenal gland was higher significantly at (P>0.05) than those of the left one.

In the hamster, statistically, the means of weight, length, width, thickness, and volume of the right and left adrenal gland were listed in (Table 3). These measurements except the width of the left adrenal gland were higher significantly at (P<0.05) than those of the right adrenal gland. The weight, length, width, thickness, and volume of the right gland parts in squirrel and hamster were (Table4). These results showed that all measurements in both right and left adrenal glands were higher significantly at (P<0.05) in squirrels than those of hamsters (Table 4). These differences may be due to species variations.

Table 1: Anatomical parameters of adrenal gland in squirrel and hamster

 Table 2: Anatomical measurements of right and left adrenal gland in squirrel

 Table 3: Anatomical measurements of right and left adrenal gland in hamster

Table 4: The anatomical measurements of adrenal gland in squirrel and hamster

Discussion

This study showed that the anatomical findings of the adrenal gland in squirrel and hamsters were paired small glands; left and right, both were situated retroperitoneal in the abdominal cavity. Generally, they were situated on each side of the vertebral column and resting on the superior poles of the corresponding kidney. Similar to that observed in domesticated cats and dogs by Ribes et al. (10) but disagree with Abbas and Shakir (11), who found packrat that the adrenal glands were located on the lower pole of the kidneys in Mexican packrat.

In the hamster, the right and left adrenal were embedded in the adipose tissue, and the right gland was slightly different in its location than the right one of squirrel, it had a convex dorsal surface that fits over the craniomedial surface (more medially than of squirrel) of the right kidney and close to the hilus of the right kidney. the liver covers it while the left adrenal rests on the left kidney cranial pole more cranially than the right one. These results were not agreeing with Abbas and Shakir (11) in Mexican pack rats in which the adrenals were located at the lower poles of the corresponding kidneys. In both squirrel and hamster, the adrenal gland was attached to the cranial pole of the corresponding kidney, similar to that reported in a cat by Laforgia et al. (12) and in spixs yellow –tooth Galea spixii (13), but disagree with Machado et al. (14) in Rattus norvegicusl in point that adrenal was separated from the kidneys. Also disagree with Mitani (15) in Albino Rats, the gland was situated interior cranial pole of the kidney and embedded in fat tissue.

 In squirrel, the right adrenal was more cranial than the left one, the same as that observed in plum mouse Myocastar caypus by Murad (16), albino rats, andguinea pigby Mitani (15) in which the right adrenal was located more cranial than the left one. Whereas in hamsters, the left adrenal gland was located cranially than the right one, this finding was disagreed disagree with that reported by Mitani (15) in albino rats and guinea pigs in which the right adrenal was more cranial than the left one, In African giant rats, the left adrenals were located on Percy and Bartholdi's kidneys (17).

 In squirrels, the external feature of the right adrenal gland showed a more elongated or (elliptical like) shape than the left one, which has a (bean-like) shape and brownish color, hamster the right adrenal appeared elongated oval to (egg-like) shape, while the left gland displays more rounded. The adrenal glands gland shapes varied in different animals (15) recorded in albino rats, the left adrenal had an oval shape, and the right adrenal gland had a bean shape. (18) and (19) were found in a study on rats which that had flattened and pyramidal shape adrenal glands. In the female guinea pig, the right adrenal appeared bean shape structure. the right adrenal gland was ovoid to a rounded shape (20,21). While Murad (16) reported that in rabbits (Oryctolagus cuniculus), the right adrenal was more elongated whereas the left was oblong, these variations may be due to species differences.

The right and left adrenal glands in both squirrels and hamsters showed soft, crusty, and dark brownish color and each of them contains a yellowish outer region which represents the cortex, and the inner dark reddish-brown region represents the medulla, as reported in most mammals as a guinea pig and albino (15). These findings were in discord with Abbas and Shakir (11), who observed that the adrenal gland in the Mexican Packrat has a light grey color, and in Kangaroo-rat, the adrenal gland has a gray color.

The mean average squirrel and hamster weight, mean total adrenal weight, mean relative weight, mean total volume was listed. The statistical analysis revealed that the mean of these measurements was significantly higher at (P>0.05) in squirrels than of hamsters, these differences may be due to species variations. In squirrel, the mean weight, length, width, thickness, volume values of the right and left adrenal gland glands were listed. The statistical analysis of results displays that the mean of these measurements of the right adrenal gland was higher significantly at (P>0.05) than those of the left one. Similar results were reported by Sheikhian et al. (22) in wild rat Rattus sikkimensis.

In the hamster, statistically, the means of weight, length, width, thickness, and volume of the right and left adrenal gland glands were listed. These measurements except the width of the left adrenal gland were higher significantly at (P<0.05) than those of the right adrenal gland. This finding coincided with Lerwill and Makings, (3) Sanjeev et al. (20) The mean width of the right adrenal was higher significantly, this finding was accorded with (23) in Logatomes Maximus Maximus and (15,20,24) in hamster and guinea pig. The weight, length, width, thickness, and volume of the right gland parts in squirrel and hamster were. These results showed that all measurements in both rights and left adrenal glands were higher significantly at (P<0.05) in squirrels than those of hamsters. These differences may be due to species variations.

Conclusions

The statistical results showed a significant difference between the left and right suitable adrenal glands in both animals, as well as a significant difference between the squirrel gland and the hamster gland, where it was found that the right and left squirrel glands are larger, heavier, longer and thicker than the adrenal gland in hamsters after the following measures were adopted: weight, length, thickness, width, and size.

Acknowledgments

The writer is very grateful to the University of Mosul, the College of Veterinary Medicine, from the Dean, his assistants, and all the respected staff of the journal.

Conflict of interest

The authors declare that there are no conflicts of interest regarding the publication of this manuscript.