A Light Microscopic Investigation of Harran Fetal Thyın as at Dıfferent Months

Thymus of 4 montlıs-, 5 months and 6 months old fötus vere investigated microscopically. For each months 5 fetal thymus used for Iliis study. Thvmus gland helps maınmalian cells to undergo maturation and plays a primary role as the immune system. T Ivmphocytes matures here, possibly, in the cortex of the thymus. Irt. tlıis study progressive expansion of Hassal's Corpuscles was maximal at 6 th month compare to 4 th and 5 th month's thymuses. Additi-onally, the prence of B lymphocytes (plasma cells) even in 4 tfj ınonth of rota! thymus indicates that stimulation of T lymphocytes and B lymphocytes in Thvmus and hınnural immune response in thymuses show the imporrance of thymus gland even in fetal development.