ROLE OF VIDEO-ASSISTED THORACOSCOPIC SURGERY (VATS) IN THYMECTOMY FOR MYASTHENIA GRAVIS

Abstract

The thymus, a key immune system organ, is the first developing lymphoid organ. In mammals it develops from the ventral portion of the third branchial pouch (endodermal epithelium) in close association with the inferior parathyroid gland.

A portion of the thymic primordium may also develop from the fourth branchial pouch in association with the superior parathyroid gland at about the sixth gestational week. (I, 2 >

The thymic primordium pinches off from the ventral portion of the third branchial pouch as thymopharyngeal duct that elongates caudally and antromedially during the seventh to the eighth gestational week. The advancing distal ends of the primordia meet and fuse at the level of the superior margin of the aortic arch.

After fusion, the distal ends of the thymus enlarge while the cephalic ends lose their connection with the pharynx and disappear during the eighth gestational week leaving a definitive thymus in the superior mediastinum. (J. 4> Fig 1

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Figure (1): A, primordial stage showing nearly development of the thymus gland from the branchial pouch. B, Definitive form showing later embryonic development of the thymus gland. From reference