Diyala Journal of Agricultural Sciences, 10(Special issue): 81-90, 2018 Alshammary et al. 18 1st Scientific Conf., College of Vet. Med., Diyala Univ., 2018 http://www.agriculmag.uodiyala.edu.iq/ HISTOMORPHOLOGICAL STUDY OF THYMUS GLAND IN THE IRAQI PIN–TAILED SANDGROUSE BIRD "Pterocles alchata caudarus" Hanaa Kareem Ali Alshammary1,4 Salah Hassan Al-Maliki2 Eqbal Salman Najem3 Khalid Ibrahim Abd Alkazraji 1 Ahmed Abdulla Hussein1 1 Dept. of Anatomy, Histology & Embryology, College of Vet. Med., Univ. of Diyala- Iraq. 2 Dept. of Anatomy, Histology and Embryology, College of Vet. Med., Baghdad Univ.- Iraq. 3 Dept. of Pathology and Poultry Diseases, College of Vet. Med., Univ. of Diyala- Iraq. 4 Corresponding author: hkareem1976@yahoo.com ABSTRACT Although avian thymus gland has been studied in several types of birds, but regarding Iraqi Alchata "Pterocles alchata caudarus", it is yet not to be done. Thus, the present study has been approved to recognize the histomorphological architecture of it. For this purpose six healthy local Alchata birds of both sexes and different ages were used and divided into two groups anatomical and histological, birds were sacrificed by slaughter with legitimate way. Morphologically thymus gland situated on both sides along the neck, it was a paired gland contain two chains of lobes each of them composed of multi lobes have irregular or flattened shape and pallid-yellowish to pinkish color; while the histological study shows that the thymus gland of alchata was totally covered with a capsule of connective tissue extend from it a number of septa split the gland into several lobules that are partially separated from one another, each of them consist of two areas, inner medulla and outer cortex. Cortex observed dark in color due to its high content of small lymphocytes that was tightly packed in the cortex than the medulla, which was composed of large amount of reticuloepithelial cells of central nuclei and acidophilic cytoplasm with large number lymphocytes of acidophilic cytoplasm, thus, the medulla appear paler. Key words: Alchata bird, histology of thymus, morphology of thymus. INTRODUCTION As it's known, that the lymphatic organs plays a vital role in the defense mechanism (Getty, 1975; Bach, 1978), according to its function and development, it can be classified into primary (central lymphatic organs) (Szenberg, 1976) and secondary (peripheral organs) (Glick, 1978). The primary lymph organs consider as the creators of lymphocyte precursors which contain thymus and bone marrow in many species of animals and in birds it include the yolk sac and cloacal bursa, in order to centralized the humoral immune responses in these structures mainly and in the thymus in the Diyala Journal of Agricultural Sciences, 10(Special issue): 81-90, 2018 Alshammary et al. 18 1st Scientific Conf., College of Vet. Med., Diyala Univ., 2018 http://www.agriculmag.uodiyala.edu.iq/ young birds (Kendall, 1980). In the other hand, the secondary organs stimulate the maturation lymphatic system cells (Rose, 1979). Thymus gland in all kinds of vertebrates considered as one of the central lymphoid organs with a main function that play a significant role in the hosting and offering of a suitable microenvironment within which T cells for the development and production of functionally competent T-lymphocytes (Mohammad et al., 2007). The differentiation of T-cells happens during they are developing through a different partitions in the thymus (Bodey et al., 2000 ; Panse, 2006 ; Berrih-Aknin, 2005). Thymus has a unique component among the lymphatic organs which is the epithelial cells that are well known for its cellular organization (Pearse, 2006), that are seemingly playing an important role in the differentiation of T- lymphocytes (Boyd et al., 1983). "Pterocles alchata" is a bird classified under the pteroclididae family of the order Pteroclidiformes, Sandgrouse is a common name of Pteroclididae, that contain about sixteen species of bird members within which Alchata. A section of them are Asian species and classified as syrrhaptes and the remainder from Africa and Asia and placed in the genus pterocles. This bird is distributed across eastern, northern and southern Africa, the Middle East and India and south to Iran and Pakistan and through to central Asia (De Juana and Boesman, 2013). Even though thymus gland has been studied in numerous types of birds, but, in the Iraqi Alchata "Pterocles alchata caudarus", not yet studied. Therefore, the current research aims to identify the histomorphological structure of it. MATERIALS AND METHODS Thymus gland of six healthy birds of the local Alchata of both sexes and different ages were used in this study and divided into two groups anatomical and histological, birds were sacrificed by slaughter with legitimate way, to observe thymus lobes along the two sides of the neck the dissection of the neck was achieved. Then the position, shape, color and boundaries were recorded in the anatomical study. While in the histological study specimens were collected from birds washed by normal saline immediately after slaughtering then fixed in 10% formaldehyde solution followed by dehydration in the series of ascending grade of alcohol (70, 80, 90, 100%) then clearing in xylene, infiltrated and later embedded in melted paraffin and finally cutting by the using of rotary microtome and the resulting sections were stained by routine stain (H & E) followed by examined under the light microscope with different powers (4x, 10x, 20x 40x) and photographed by digital camera (Bancroft et al., 2013). Diyala Journal of Agricultural Sciences, 10(Special issue): 81-90, 2018 Alshammary et al. 18 1st Scientific Conf., College of Vet. Med., Diyala Univ., 2018 http://www.agriculmag.uodiyala.edu.iq/ RESULTS AND DISCUSSION Anatomical results: The gross morphological study revealed that thymus gland in the local Alchata "Pterocles alchata caudarus" situated on both sides along the neck, closely to the esophagus, trachea, common carotid artery, jugular vein, and brachial plexus at the thoracic inlet. It was a paired gland contain two chains of lobes each of them composed of frequent lobes about four to six irregular to flattened in shape lobes of yellowish to pinkish color (Fig. 1), these results comparable to that of Getty (1975); kendall (1980); king and McLeland (1984) in chicken; Sultana et al., (2011) in duck; Tarek et al., (2012) in broiler chicken. The caudal lobe of the thymus located in contact with the thyroid gland (Fig. 2) similar to that mentioned by Hodges (1974) in chicken; Bowden (2005) in toloests; Song et al., (2012) in ostrich. Histological Results: Thymic sections that stained by Hematoxylin and Eosin stain observed that thymus gland contained many lobes embedded in the adipose tissue and covered completely by a thin capsule of connective tissue (Fig. 3). The capsule sent numerous delicate septa extended from it into the parenchyma of the gland and dividing it into partially separated lobules. Each of these lobules contain two areas without any mark of separation, inner lightly stained medulla and outer darkly stained cortex (Fig. 4), parallel findings was also observed by Treesh et al., (2014); Kannan et al., (2012; 2015) in chicken. The cortex positioned along the periphery of the gland and observed dark in color and more basophilic because of its enriched content with lymphocytes which was numerous and tightly packed in the cortex than in the medulla forming the major cellular population of the parenchyma (Fig. 4 and 7). Another cell type also found in the cortex was the Reticuloepithelial cells (RECs) but in small number and smaller size and lighter color than that of the medulla, (RECs) inside the cortex were stellate in shape with one or two nuclei (Fig. 5 and 6), they thought to be serve as supportive network in the cortical region for lymphocytes and macrophages, similar findings previously mentioned by Song et al., (2012) in ostrich; Dellmann and Brown (1998); Kannan et al., (2015) in chicken. The inner medulla was the second composition of thymic parenchyma which composed of large amount and bigger size and darker color of reticuloepithelial cells (RECs) which has central nuclei and eosinophillic cytoplasm beside a large number of medium and small lymphocytes of acidophilic cytoplasm, thus, the medulla appear pail in color (Fig. 4,6 and 7), Diyala Journal of Agricultural Sciences, 10(Special issue): 81-90, 2018 Alshammary et al. 18 1st Scientific Conf., College of Vet. Med., Diyala Univ., 2018 http://www.agriculmag.uodiyala.edu.iq/ these results was in agreement with Honjo and Hirota (1993); Khalil et al., (2003); Karim et al., (2005) and Ali (2017) in chicken. Inside the medulla the reticuloepithelial cells and lymphocytes collected together gradually ending in the formation of Hassall’s corpuscles, which have structureless hyalinized center and concentrically arranged reticuloepithelial cells in the peripheral (Fig. 7), and their function not yet known. Also they might be gathered and changing into reticular structures which are abundant in the medulla, they appear as irregular masses of vacuoles of different sizes filled later with eosinophilic homogenous material which thought to be as a result of degenerating reticuloepithelial cells, (Fig. 6 and 7), analogous results were recorded by Bacha and Bacha (2000) in chicken; Sultana et al., (2011) in duck; Elewa (2005); Elzoghby and Attia (2007) in ostrich and Ali (2016) in turkey "Meleagris gallopavo". Fig. 1. Photography of Thymus gland of Alchata (arrows) embedded in the connective tissue closely to a- esophagus, b- trachea, c- jugular vein and brachial plexus at the thoracic inlet Diyala Journal of Agricultural Sciences, 10(Special issue): 81-90, 2018 Alshammary et al. 18 1st Scientific Conf., College of Vet. Med., Diyala Univ., 2018 http://www.agriculmag.uodiyala.edu.iq/ Fig. 2. Photography of Thymus gland of Alchata composed of frequent lobes of yellowish to pinkish color (T). The caudal lobe of the thymus located in contact with the thyroid gland (arrow), a- common carotid artery, b- jugular vein, c- trachea, d- heart Fig. 3. Histological section of thymus gland showed: a: adipose connective tissue, L: thymic lobes C: capsule (H & E stain, 40 X) Diyala Journal of Agricultural Sciences, 10(Special issue): 81-90, 2018 Alshammary et al. 18 1st Scientific Conf., College of Vet. Med., Diyala Univ., 2018 http://www.agriculmag.uodiyala.edu.iq/ Fig. 4. Histological section of thymus gland showed: a: cortex, b: medulla, c: capsule, s: septa (H & E stain, 100 X) Fig. 5. Histological section showed: c: capsule, L: lymphocytes inside the cortex, RECs: reticuloepithelial cells inside the cortex (arrow heads) (H & E stain, 400 X) Diyala Journal of Agricultural Sciences, 10(Special issue): 81-90, 2018 Alshammary et al. 18 1st Scientific Conf., College of Vet. Med., Diyala Univ., 2018 http://www.agriculmag.uodiyala.edu.iq/ Fig. 6. Histological section showed: a: capsule, C: cortex, RECs in the cortex (red arrow heads), M: medulla, RECs inside the medulla (black arrow heads), v: vacuoles (H & E stain, 400 X) Fig. 7. Histological section of thymus gland showed: C: cortex with dark lymphocytes, M: medulla containing lighter lymphocytes and larger RECs (arrow heads), H: Hassall's corpuscle, v: vacuoles. (H & E stain, 400 X) Diyala Journal of Agricultural Sciences, 10(Special issue): 81-90, 2018 Alshammary et al. 11 1st Scientific Conf., College of Vet. Med., Diyala Univ., 2018 http://www.agriculmag.uodiyala.edu.iq/ REFERENCES Ali, H. K. 2016. Anatomical and Histological study of thymus gland in the local breed of turkey “Meleagris gallopavo” in Iraq. 3rd Scientific Conference - College of Veterinary Medicine - University of Tikrit. 2,3 May: 93-97. Ali, H. K. 2017. Histomorphological Study of Thymus in Local Chicken "Gallus gallus domesticus". Diyala journal for pure sciences, 13(3): 120-132. Bach, J. F. 1978. 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International Journal of Histology and Cytology, 1(11): 103-111. دراسة نسيجية شكلية للغدة الزعترية في طائر القطا العراقي 3 اقبال سلمان نجم 2صالح حسن المالكي 4 ، 1هناء كريم الشمري عبدهللا حسينأحمد 1خالد ابراهيم الخزرجي 1 hkareem1976@yahoo.comالمسؤول عن النشر: 8 مستخلصال بالقطا لم تدرس على الرغم من أن الغدة الزعترية قد درست في عدة أنواع من الطيور، ولكنها ، خصصت هذه الدراسة للتعريف بالتركيب الشكلي والنسيجي لهذه الغدة. استخدمت اولذ ،الى االن العراقي قسمت إلى وعمار المحلي من كال الجنسين ومختلف األلهذا الغرض ستة طيور صحية من القطا وتم قتل الطيور بطريقة الذبح الحالل. ،مجموعتين تشريحية ونسيجية لجانبين على طول الرقبة، وهي غدة مزدوجة تحتوي على شكلياً كانت الغدة الزعترية تقع على كال ا سلسلتين من الفصوص كل منها يتألف من عدة فصوص مفلطحة أو غير منتظمة الشكل ذات لون وردي بينما بينت الدراسة النسيجية ان الغدة الزعترية في طائر القطا كانت محاطة كليا بمحفظة من ،مصفر لحواجز التي تقسم الغدة الى عدة فصيصات منفصلة عن بعضها جزئيا، النسيج الضام يمتد منها عدد من ا وكل منها تتكون من منطقتين هما منطقة داخلية هي اللب واخرى خارجية هي القشرة. إحكام الليمفاوية الصغيرة والمرصوفة ب كانت القشرة داكنة اللون بسبب محتواها العالي من الخاليا مركزية الشبكية الطالئيةفي منطقة القشرة اكثر من منطقة اللب، التي تألفت من كمية كبيرة من الخاليا مع عدد كبير من الخاليا الليمفاوية ذات الهيولي ذو الصبغة والهيولي ذو الصبغة الحامضية النواة .الحامضية، مما يعطي اللب المظهر الشاحب الزعترية. للغدة شكلية دراسة، الزعترية للغدة النسيجي التركيب ،القطاطائر الكلمات المفتاحية: