THE BLOOD OF CHICK EMBRYOS
211
counts in vitamin B 12 deficient embryos at the 18th day of incubation
were significantly lower (1-65 million/cu.mm) than in vitamin B 12
supplemented embryos (2-23 million/cu.mm) (Hsu et al., 1952). Vitamin B 12 injected into eggs on the 2nd day of incubation caused an
increase from 1% to 28% in basophilic erythroblasts (Ε II) on the 3rd
day of incubation (Carrara et al., 1960). The effect of insulin and
glucagon on primitive erythropoiesis in chick embryos was studied by
Butturini et al. (1957). The maturation of primitive elements (Ε I)
in the presence of various substances was studied by Bussi et al. (1956,
1958).
Injection of blood from human leukaemias into fertile hen eggs before
their incubation caused a reticuloendotheliosis of 40-6% in the circulating blood of an 84-hour-old chick embryo (Torrioli and Riggio, 1941;
Torrioli and Torrioli, 1951). On the other hand, intravenous inoculation
of various materials of leukaemic origin on the 11th to the 14th day of
incubation was not followed by any haematological changes except in
some hatched chicks which showed more polychromatophilic or even
basophilic erythroblasts (Giordano et al., 1955).
Stauber and van Dyke (1945) observed in artificial malarial infection
of duck embryos the presence of the parasites in primitive erythrocytes.
Infiltrations on the chorioallantoic membrane after infection with
Rickettsia
orientalis
exhibited amoeboid 'round cells', which were
probably stem cells (haemocytoblasts) (Hamilton, 1946).
The embryonic haemoglobin deserves some comment. Haemoglobin
appears first in the developing blastoderm at the 6-7 somite stage, as
detected by the benzidine method (Slonimski, 1927). Haemoglobin first
becomes apparent in the nucleolus, then in the perinuclear space in the
cytoplasm, and lastly in the nucleus proper (O'Brien, 1961). Further
details of the early stages of haemoglobin formation are given by
D'Amelio and Salvo (1959) and O'Brien (1961). Ascarelli (1895)
observed that embryonic haemoglobin is unable to form Teichman's
crystals until the 13th day of development. Hall (1934) demonstrated
that the dissociation curve of chick embryo haemoglobin is gradually
moved to the right, thus showing a diminishing affinity for oxygen as
incubation proceeds. This process is not finished until the 40th postembryonic day. No correlation of this peculiar behaviour of chick
embryo haemoglobin, examined as a weak solution, can be made with
the different types of erythrocytes. The explanation that it might be
caused by two types of erythrocytes, one produced in the yolk sac and
the other in the bone marrow, seems improbable when the short life
span of embryonic erythrocytes is taken into account (Section II, G).
The dissociation curve of the whole blood, which is most important from
a physiological point of view, has not yet been studied in chick embryos.
211
counts in vitamin B 12 deficient embryos at the 18th day of incubation
were significantly lower (1-65 million/cu.mm) than in vitamin B 12
supplemented embryos (2-23 million/cu.mm) (Hsu et al., 1952). Vitamin B 12 injected into eggs on the 2nd day of incubation caused an
increase from 1% to 28% in basophilic erythroblasts (Ε II) on the 3rd
day of incubation (Carrara et al., 1960). The effect of insulin and
glucagon on primitive erythropoiesis in chick embryos was studied by
Butturini et al. (1957). The maturation of primitive elements (Ε I)
in the presence of various substances was studied by Bussi et al. (1956,
1958).
Injection of blood from human leukaemias into fertile hen eggs before
their incubation caused a reticuloendotheliosis of 40-6% in the circulating blood of an 84-hour-old chick embryo (Torrioli and Riggio, 1941;
Torrioli and Torrioli, 1951). On the other hand, intravenous inoculation
of various materials of leukaemic origin on the 11th to the 14th day of
incubation was not followed by any haematological changes except in
some hatched chicks which showed more polychromatophilic or even
basophilic erythroblasts (Giordano et al., 1955).
Stauber and van Dyke (1945) observed in artificial malarial infection
of duck embryos the presence of the parasites in primitive erythrocytes.
Infiltrations on the chorioallantoic membrane after infection with
Rickettsia
orientalis
exhibited amoeboid 'round cells', which were
probably stem cells (haemocytoblasts) (Hamilton, 1946).
The embryonic haemoglobin deserves some comment. Haemoglobin
appears first in the developing blastoderm at the 6-7 somite stage, as
detected by the benzidine method (Slonimski, 1927). Haemoglobin first
becomes apparent in the nucleolus, then in the perinuclear space in the
cytoplasm, and lastly in the nucleus proper (O'Brien, 1961). Further
details of the early stages of haemoglobin formation are given by
D'Amelio and Salvo (1959) and O'Brien (1961). Ascarelli (1895)
observed that embryonic haemoglobin is unable to form Teichman's
crystals until the 13th day of development. Hall (1934) demonstrated
that the dissociation curve of chick embryo haemoglobin is gradually
moved to the right, thus showing a diminishing affinity for oxygen as
incubation proceeds. This process is not finished until the 40th postembryonic day. No correlation of this peculiar behaviour of chick
embryo haemoglobin, examined as a weak solution, can be made with
the different types of erythrocytes. The explanation that it might be
caused by two types of erythrocytes, one produced in the yolk sac and
the other in the bone marrow, seems improbable when the short life
span of embryonic erythrocytes is taken into account (Section II, G).
The dissociation curve of the whole blood, which is most important from
a physiological point of view, has not yet been studied in chick embryos.