This document describes the development stages of erythrocytes (red blood cells) from earliest precursors to mature cells. It outlines 14 key stages from rubriblast through reticulocte to mature erythrocyte. Each stage is characterized by changes in size, shape, nuclear morphology, chromatin patterns, cytoplasmic coloration, and other cellular features visible under light microscopy during the bone marrow smear process.

1. Description Size Nucleus Cytoplasm Golgi Apparatus
Rubriblast: >Earliest erythrocyte precursor 12‐25um Round/slightly oval Basophilic Visible pale area
*Pronormoblast >Seen under light microscope Chromatin: dispersed fine clumps Intense DARK BLUE next to nucleus
*Proerythroblast using WRIGHT‐stained BM sample Nucleoli: present High RNA:
Occupying 80% of the cell (attracts the basic part of the stain)
Inc. N:C ratio Methylene Blue stain
Prorubricyte: 12‐17um Round Basophilic Visible as light area
*Basophilic Normoblast Presence of Parachromatin Chromatin: coarser, more clumped near the nucleus
*Basophilic Erythroblast Divides twice and give rise Nncleoli: absent
to 4 rubricyte Occupying 75% of the cell
Parachromatin: slightly visible
btwn the clumps of chromatin
Rubricyte Polychromasia or 12‐15um Round, may be eccentric More as nucleus becomes smaller
*polychromatophilic Polychromatophilia Chromatin: coarser, condensed Synthesis of Hb begins
Normoblast Can be confused with lymphocyte "Chunky app." Blue RNA mixed with red Hb
*polychromatophilic Last cell division Blue‐gray‐violet color
Erythroblast Gives rise to 2 metarubricytes
Metarubricyte BM: metarubricyte 8‐12um Pyknotic, at the periphery Paler, more pinkish than rubricyte
*orthochromic PB: NRBC Chromatin: very dense, coarse and clump Violet‐blue‐gray color
Normoblast Nucleus is extruded at this stage Nucleoli: present
*orthochromic ***Howell‐Jolly body Last nucleated cell
Erythroblast
Reticulocyte Slightly larger than mature erythrocyte Irregular cytoplasmic borders Golgi remnants
*diffusely basophilic Retained in bone marrow for 2‐3days Cytoplasm contains small amt of RNA Mitochondria remnants
erythrocyte Residual RNA: producing varying amt of polychromasia
*polychromatophilic Supravital staining (in living state)
Macrocyte *new methylene blue
*brillant cresyl blue
Release from BM in 24‐48 hours
Mature erythrocyte No mitochondria Henry: 6‐8um Biconcave disc shape Central area of pallor:
*normocyte No protien and Hb sepynthesis Thickness: 2.5um Flexible With reddish‐pink or salmon pink
*discocyte Deformable ability It respond to the indentation in the disc