210
LEO LEMEÈ
of 32P by the RNA of embryonic erythropoietic cells (Tamburino et al.,
1956) was more active in megaloblastic cells (Ε I) than in normoblastic
(Ε II) ones and more active in earlier stages than in later stages of
maturation.
Burke et al. (1944) and Briles et al. (1948) found that embryonic
erythrocytes began to develop an antigen common to the erythrocyte of
the adult at about 100 hours of incubation, that is, just after the 4th
day. Obviously cells of the primitive line (Ε I) are responsible
for the reaction. The evidence for a specific embryonic erythrocyte
antigen limited to embryonic life was given by Levi and Schechtman
(1954).
Phagocytosis of Indian ink particles was described as occurring in
primitive erythrocytes up to the 3rd day of incubation (Heine, 1936;
Steinmüller, 1937). The illustrations reveal, however, only some adsorbed
particles on the surface of primitive red blood cells. Using more accurate
methods, Dabrowska (1951) could not find any phagocytosis in red
blood corpuscles, while histiocytes phagocytosed from the 5th day and
white blood cells were found to do so between the 10th and 20th day of
incubation. When erythrocytes, stained with trypan blue, were injected
into the circulation during the second half of the incubation period they
were rapidly removed from the blood stream after 5 minutes, while
spleen smears showed large numbers of them (Yosphe-Purer et al., 1953).
Further data on the development of the phagocytic activity of the
chick embryo reticuloendothelial system are given by Okkels (1931),
Barka et al. (1955), Leghissa (1958), Kent (1961), and Nicol et al.
(1962).
Increased atmospheric pressure acting during the first 10 days of
incubation retarded the development of the allantoic vessels. The erythrocyte count in experimental embryos was 0-86 million/cu.mm as compared
with 1-88 million/cu. mm in controls. The haemoglobin content was
in the same proportion in both groups (Flemister and Cunningham,
1940).
According to Astaldi and Meardi (1958) the polychromatophilic
maturation of basophilic megaloblasts (Ε I) occurred at a faster rate in
embryos treated with cobalt than in controls, without any increase in
the relative number of normoblastic elements (Ε II).
The effects of various haemopoiesis-stimulating drugs (liver extract,
folic and folinic acid) on predominantly megaloblastic haemopoiesis
(Ε I) were studied in vitro (Sabin, 1928; Muller, 1930; Perri et al, 1951b,
c, 1953) and in vivo (Reimer, 1938; Hays et al., 1942; Riggio, 1942;
Perri, 1948a, b; Carrara et al., 1960). The results were partly negative,
but in some cases a reduction in size of primitive elements was observed.
The mitotic activity remained unchanged in most instances. Red cell
LEO LEMEÈ
of 32P by the RNA of embryonic erythropoietic cells (Tamburino et al.,
1956) was more active in megaloblastic cells (Ε I) than in normoblastic
(Ε II) ones and more active in earlier stages than in later stages of
maturation.
Burke et al. (1944) and Briles et al. (1948) found that embryonic
erythrocytes began to develop an antigen common to the erythrocyte of
the adult at about 100 hours of incubation, that is, just after the 4th
day. Obviously cells of the primitive line (Ε I) are responsible
for the reaction. The evidence for a specific embryonic erythrocyte
antigen limited to embryonic life was given by Levi and Schechtman
(1954).
Phagocytosis of Indian ink particles was described as occurring in
primitive erythrocytes up to the 3rd day of incubation (Heine, 1936;
Steinmüller, 1937). The illustrations reveal, however, only some adsorbed
particles on the surface of primitive red blood cells. Using more accurate
methods, Dabrowska (1951) could not find any phagocytosis in red
blood corpuscles, while histiocytes phagocytosed from the 5th day and
white blood cells were found to do so between the 10th and 20th day of
incubation. When erythrocytes, stained with trypan blue, were injected
into the circulation during the second half of the incubation period they
were rapidly removed from the blood stream after 5 minutes, while
spleen smears showed large numbers of them (Yosphe-Purer et al., 1953).
Further data on the development of the phagocytic activity of the
chick embryo reticuloendothelial system are given by Okkels (1931),
Barka et al. (1955), Leghissa (1958), Kent (1961), and Nicol et al.
(1962).
Increased atmospheric pressure acting during the first 10 days of
incubation retarded the development of the allantoic vessels. The erythrocyte count in experimental embryos was 0-86 million/cu.mm as compared
with 1-88 million/cu. mm in controls. The haemoglobin content was
in the same proportion in both groups (Flemister and Cunningham,
1940).
According to Astaldi and Meardi (1958) the polychromatophilic
maturation of basophilic megaloblasts (Ε I) occurred at a faster rate in
embryos treated with cobalt than in controls, without any increase in
the relative number of normoblastic elements (Ε II).
The effects of various haemopoiesis-stimulating drugs (liver extract,
folic and folinic acid) on predominantly megaloblastic haemopoiesis
(Ε I) were studied in vitro (Sabin, 1928; Muller, 1930; Perri et al, 1951b,
c, 1953) and in vivo (Reimer, 1938; Hays et al., 1942; Riggio, 1942;
Perri, 1948a, b; Carrara et al., 1960). The results were partly negative,
but in some cases a reduction in size of primitive elements was observed.
The mitotic activity remained unchanged in most instances. Red cell