Pathoma: - Lymphocytes are the most sensitive cells to whole body radiation - Granulocytes (Mainly neutrophils) are particularly very sensitive to chemotherapeutic alkylating agents (requiring G-CSF shortly after)

Another way to approach this is asking yourself which of these cell types are likely undergoing the most mitotic activity. The granulocyte precursors are likely dividing more than nerves or lymphocytes (in absence of infection). This was my approach.

https://qph.fs.quoracdn.net/main-qimg-1e53e64c8df300f79fc14781538874c4.webp

This question is asking how much reserve capacity there is of each compartment, of which the granulocytes have the least.

Note that myelosuppression can refer to any lineage (including lymphocytes).

This is the second time in NBME23 asking about the definition and of stable and labile cell~Just a another way to reach the answer It is IMP to ddx
1:lymphocyte (stable) vs Bone marrow(labile,maybe point to granulocyte here) 2.gut epithelium(labile) not endothelium Then rule out liver(stable) and neuron(permanent )

From FA： Stable (quiescent) ：Enter G1 from G0 when stimulated. Hepatocytes, lymphocytes, PCT, periosteal cells.

Labile ：Never go to G0, divide rapidly with a short G1. Most affected by chemotherapy. Bone marrow, gut epithelium, skin, hair follicles, germ cells.

Another way to get this is to think about chemotherapy-induced neutropenia. Since we check absolute neutrophil count, it must be granulocytes that are the most impacted

One of the side effects of Cyclophosphamide is myelosuppression.

See full list of side effects below:

Myelosuppression; SIADH; Fanconi syndrome (ifosfamide); hemorrhagic cystitis and bladder cancer, prevented with mesna (sulfhydryl group of mesna binds toxic metabolites) and adequate hydration.