Here's a breakdown of the process:

1. Erythropoiesis: The process of red blood cell production begins in the bone marrow with erythroid progenitor cells. These cells differentiate and mature through a series of stages.

2. Stages of Maturation: These stages include:

* Proerythroblast: The earliest recognizable stage.

* Basophilic erythroblast: Synthesizes hemoglobin, giving it a bluish color.

* Polychromatic erythroblast: Continues hemoglobin synthesis, leading to a mixed color.

* Orthochromatic erythroblast: Almost fully mature, containing mostly hemoglobin.

* Reticulocyte: Releases from the bone marrow and enters the bloodstream. It still contains some remnants of cellular organelles.

3. Mature Erythrocyte: Within a day or two of entering the bloodstream, reticulocytes lose their remaining organelles and become fully mature erythrocytes.

Key Point: Bone marrow is the primary site of erythropoiesis, where red blood cells are produced and mature.