Question

B-lymphocytes are:

• A. Formed in bone marrow
• B. Preprocessed in bone marrow
• C. Preprocessed in liver
• D. Both formed in bone marrow and preprocessed in bone marrow

Hint:

B-cells → Formed \& matured in bone marrow
T-cells → Formed in bone marrow, matured in thymus Remember this distinction for immunity-related questions.

Answer 1

The Correct Option is D

Step 1: Recall the origin of lymphocytes. All lymphocytes originate from hematopoietic stem cells present in the bone marrow.
Step 2: Understand B-lymphocyte maturation.
B-lymphocytes are formed in the bone marrow.
They also undergo preprocessing (maturation) in the bone marrow itself. (The letter B in B-lymphocytes originally stands for \emph{Bursa of Fabricius} in birds, but in humans, this function is carried out by the bone marrow.)
Step 3: Eliminate incorrect options.
(A) Incomplete — does not mention preprocessing.
(B) Incomplete — ignores formation.
(C) Incorrect — liver is not involved in lymphocyte maturation.
Hence, the correct answer is \[ \boxed{\text{Both formed in bone marrow and preprocessed in bone marrow}} \]