15.有關紅血球演進之敘述，下列何者正確？
(A)牛只有成熟的紅血球才會進入末梢血液
(B)通常一個紅血胚細胞分裂後形成8個紅血球
(C)犬的骨髓相較於牛馬的骨髓具有更大增加紅血球形成的潛力
(D)EPO於缺氧時主要由肝臟細胞生成

補充馬血中沒有網狀球的研究：

The processes that contribute to maturation of young RBC in horses most likely involve very effective control over membrane loss and over the intracellular Ca2+ maintenance. As a result, premature damage is avoided and the longevity of RBCs is supported. Oxidative stress, as well as the growing density and stiffness of senescent horse RBC most likely trigger their clearance. More work, particularly at the level of bone marrow, has to be done to unravel the mysterious cause for of the lack of reticulocytes in peripheral blood of horses.

簡單來說，馬的RBC成熟機制比較完善，且容易刺激RBC清除機制，所以血中沒有網狀球。

（reference: https://doi.org/10.3389/fphys.2019.00893）

不明白時選字數多的即可