Blood.

INTRODUCTION I N A RECENT study of primitive erythroblasts,’ it was shown that cytoplasmic areas originaLy interpreted as hyaloplasm by hematologists actually represent negative images of underlying cell organoids-mitochondria and Golgi elements. This finding immediately unfolded many interesting problems concerning erythoblasts in general, especially since it was shown that cell organoids may be preserved in good dry smears. How long do mitochondria retain their vitamin A content? Do the more mature erythroblasts contain mitochondria which have lost their affinity for acid fuchsin and supravital dyes? How long do mitochondria persist in non-nucleated corpuscles of the primitive and definitive generations?2’3 What happens to the chromophilic and chromophobic portions of the Golgi element as primitive erythroblasts mature?4 Do these elements contain vitamin C?5 How do these organoids respond under the influence of antipernicious anemia substances? In order to investigate some of these problems various preparations were made from the 15 day rat embryonic liver. A study of lymphoid cells (i.e., any ccl] with hasophilic, nongranular cytoplasm, regardless of its nuclear detail) by means of phase microscopy revealed the presence of more cell organoids, particularly mitochondria, in definitive erythroblasts than had been observed in primitive erythroblasts. Furthermore, most of these organoids were contained in the thin layers of cytoplasm above and below nuclei as seen in dry smears. Although it had been observed previously that some sudanophilic material may be distributed in these regions in primitive erythroblasts from ii day rat embryos,’ the significance of this finding was not appreciated fully until rat and human fetal liver material were studied. Since the implications derived from these observations might markedly alter present day concepts in practical and theoretic morphologic hematology,6 it was deemed necessary to forego the other problems and to undertake the present one dealing with nuclei as seen in dry smears.