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Subject: Veterinary Anatomy × Start date: 2017 × Type: Thesis × Thesis Type: M.V.Sc. ×
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    ThesisItemOpen Access
    POSTNATAL DEVELOPMENT OF THYMUS OF ASSAM HILL GOAT (Capra hircus)
    (College of Veterinary Science, Assam Agricultural University Khanapara, Guwahati-781022, 2017-07) Medhi, Banajit Kumar; Talukdar, Manmath
    Goat is one of the most important species in livestock industry. Literature pertaining to the thymus of goat are very scanty in general and almost not available in Assam hill goat in particular, hence the present investigation was carried out to establish a baseline on the anatomical aspect of the thymus gland of Assam hill goat at various age groups viz. day old, 3 month and 6 month. Eighteen (18) numbers of goats divided into 3 (three) groups, consisting of 6 animals in each group according to their age were utilized for the present study. Detailed anatomical study on gross, histomorphological and histochemical aspect of thymus gland along with some hematological , biochemical and hormonal parameters of Assam hill goat at different stages of development were performed with these animals . In the present investigation , the morphometrical parameters of the thymus gland in Assam hill goat showed an increased value at 3 month of age group in compared to day old kids while it showed a decreased value at 6 month age group. The average weight of the thymus gland in Assam hill goat was found to be increased in 3 month of age group in compared to day old kids and the study also revealed a decrease value in 6 month old age group . The percentage of thymus weight to body weight decreased with advancement of age . The average length , width and thickness of thoracic, isthmus, and cervical parts of thymus gland in Assam hill goat increased in 3 month age group in compared to day old kids and thereafter showed a decrease value in 6 month age group. Histology of the thymus gland of Assam hill goat found to be observed that the gland was covered by a thin capsule enclosing numerous lobules demarcating the gland in all the age groups . The capsule was made up of mainly collagen fiber besides a few amount of reticular and elastic fiber .The connective tissue septa arising from the capsule divided the gland into numerous lobes and lobules which were oval to polyhedral in shape .The connective tissue septa were predominantly consisted of collagen fiber with a few amount of reticular fibers. The presence of elastic fiber in all age groups of goats were found to be very scanty. Nerve fibers were observed in all the three age groups. Each lobule were composed of outer dark cortex and inner pale medulla. The cortex predominantly consisted of densely packed small round or ovoid thymocytes with dark stained nuclei. The medulla consisted of relatively loosely packed larger thymocytes and more fibrous stroma containing some spheroid to oval eosinophilic body called Hassall’s corpuscle . The sub capsular and the interlobular connective tissue were found to be replaced by fatty tissue which was observed in 6 month old age group indicating the involutionary changes. The micrometry of different parameters of the thymus gland revealed that the thickness of the capsule increased with advancement of age .The size of the lobules were found to be increased in 3 month of age and thereafter it showed a decreased value in 6 month age group. The thickness of cortex was increased in 3 months age group in compared to day old kids and thereafter it showed a decreased value in 6 month age group, while the thickness of the medulla was found to be increased with advancement of age. The numbers of Hassall’s corpuscle per lobule increased with advancement of age while the diameter of the same decreased with advancement of age. Histochemical study revealed that the alkaline phosphatase showed strong reactivity in day old age group while it showed a moderate activity in 3 month and 6 month old age group .However the acid phosphatase showed a moderate activity in day old age group while the same showed a strong activity in 3 month and 6 month age group. Biochemically, the average serum alkaline phosphatase level was observed to be declined with advancement of age from day old kids to 6 month old age group with significant difference between day old and 3 month old age group and also between day old and 6 month, while there was no significant difference found between 3 month and 6 month age groups. However there was no significant difference found in serum acid phosphatase level among different age groups. The average serum triiodothyronine ( T3) and thyroxine (T4) hormone level was found to be decreased in 3 month old age group in compared to day old kids and after that it showed an increased value in 6 months old age group. The hematological parameters showed that the hemoglobin level decreased from day old to 6 month age groups. The TLC level increased from day old to 3 month and thereafter it showed a decreased value in 6 month age group. However, the TEC level showed increased value from day old to 6 month age group. The PCV level was found to be decreased from day old to 3 month age groups and thereafter it showed an increased value at 6 month age group. From the present investigation it might be concluded that most of the parameters under study showed a remarkably differed value between the various age groups of Assam hill goat. This might be due to the various anatomical, biochemical, physiological, immunological and adaptive changes in body pertaining to the advancement of age in Assam hill goat.