ABSTRACT
Introduction: Thymus consists of two pyramidal lobes. It is located in the mediastinum behind the sternum andin front of the pericardium and great vessels of the heart. The present study has been undertaken to highlightsome important points in morphometry of foetal thymus gland.Materials and Methods: In the present study 30 foetuses (12-38 week) were studied. The obtained foetuses werefixed in 10% formalin. After proper fixation they were subjected to dissection. The length and breadth of glandwas measured by vernier caliper in centimeters. Weight of the gland was measured using electronic weighingmachine. Naked eye examination done for number of lobes.Results: The average length of the thymus at 12th week was 0.2cm on right side and 0.2cm on left side, it wasincreased to 4cm on right side and 4.5cm on left side. The average breadth of thymus was 0.12cm on right sideand 0.10cm on left side at 12th week which was increased to 2.2cm and 2.6cm on right & left side respectively at38th week. The average weight of thymus was 0.1 gm at 12th week and 8.2 gm at 38th week. The majority of thymus26(86.67%) shows presence of two lobes.Conclusion: All parameters length, breadth and weight of thymus show gradual increase with advancing gestationalage with significant changes. There are wide variations in number of lobes of thymus gland.
ABSTRACT
Introduction: The thymus is a primary lymphoid organ. It is a bilobed structure divided into lobules by theconnective tissue septa. Each lobule consists of a cortex and medulla. Most of the studies regarding early foetalhistology of this organ are animal based. The present study has been undertaken to highlight some featuresregarding histogenesis of human foetal thymus.Materials and Methods: In the present study, 30 normal human stillborn/aborted foetuses were studied. Theobtained foetuses were fixed in 10% formalin. After proper fixation they were subjected to dissection. Theobtained specimens were processed by standard paraffin block making procedure. Sections were taken andstained with haematoxylin & eosin. The stained sections were examined under light microscopy using 10x and40x optical magnifications and photographs taken.Results: At 12th week, capsule was thin and cortico-medullary differentiation not much prominent. Epithelialcells and lymphocytes were present. Hassall’s corpuscles were very small and immature. Distinct lobulation wasseen at 18th week with well differentiated cortex and medulla. The gland became more distinct from 21stweekonwards with increased number of Hassall’s corpuscles of various types. 29 week onwards the thymus glandrevealed an adult histological picture.Conclusion: All structural changes viz cortico-medullary differentiation, lobulation and maturity of Hassall’scorpuscles occurred within the first 18 weeks of gestation.