This paper by George E. Palade, published in 1954, introduces the discovery of a small particulate component in the ground substance of animal cells, particularly in mammalian and avian cells. This component, which is 100 to 150 Å in diameter and highly dense, is found in various cell types, though its presence varies. It is most abundant in cells with high differentiation, such as embryonic cells and rapidly proliferating adult cells, and is less common in granulocytes and seminal epithelia. The particles are often associated with the endoplasmic reticulum, forming patterns like parallel rows, loops, spirals, circles, and rosettes. The association is not solely due to fixation artifacts, as the particles are also found in cells fixed with formaldehyde. The small granules are rich in RNA, suggesting a role in cytoplasmic basophilia. The study integrates these findings with existing cytological, histochemical, and cytochemical data, providing insights into the structure and function of this novel component.This paper by George E. Palade, published in 1954, introduces the discovery of a small particulate component in the ground substance of animal cells, particularly in mammalian and avian cells. This component, which is 100 to 150 Å in diameter and highly dense, is found in various cell types, though its presence varies. It is most abundant in cells with high differentiation, such as embryonic cells and rapidly proliferating adult cells, and is less common in granulocytes and seminal epithelia. The particles are often associated with the endoplasmic reticulum, forming patterns like parallel rows, loops, spirals, circles, and rosettes. The association is not solely due to fixation artifacts, as the particles are also found in cells fixed with formaldehyde. The small granules are rich in RNA, suggesting a role in cytoplasmic basophilia. The study integrates these findings with existing cytological, histochemical, and cytochemical data, providing insights into the structure and function of this novel component.