OVERVIEW OF THE IMMUNE SYSTEM
LYMPHATIC AND IMMUNE SYSTEM
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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adenoids
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spleen
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tonsils
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thymus
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Detailed explanation-1: -Lymphocytes of the B series develop in the liver by 9 weeks’ gestation and are present in the blood and spleen by 12 weeks. T lymphocytes start to leave the thymus from about 14 weeks’ gestation and subsequently cells with helper and suppressor phenotypes are present in the spleen.
Detailed explanation-2: -T lymphocytes develop from a common lymphoid progenitor in the bone marrow that also gives rise to B lymphocytes, but those progeny destined to give rise to T cells leave the bone marrow and migrate to the thymus (see Fig. 7.2). This is the reason they are called thymus-dependent (T) lymphocytes or T cells.
Detailed explanation-3: -thymus: A ductless gland consisting mainly of primary lymphatic tissue that is the site of lymphocyte maturation and selection.
Detailed explanation-4: -T cells originate in the bone marrow and mature in the thymus. In the thymus, T cells multiply and differentiate into helper, regulatory, or cytotoxic T cells or become memory T cells.