THE BLOOD OF CHICK EMBRYOS
239
Only three investigations have been concerned with the cytology of
the blood contained in the vessels of the surviving vascular area.
Byerly (1926a, b) suffocated chick embryos after 24, 72, or 96 hours of
incubation by coating the eggs with water-glass. These eggs were then
incubated up to a maximum of 10 days of total incubation. At the end
of this period the only living portion was a peripheral ring of the
vascular area, in which, as seen in histological sections, many erythrocytes were haemolysed or binucleate (caryokinesis was obviously not
followed by cytokinesis, due to impairment of living conditions) ; the
frequent mitoses in earlier stages had disappeared completely by the
9th day. The self-differentiation of leucocytes remained uncertain.
Thrombocytes were not mentioned. Undoubtedly, Byerly observed
other cell types, especially definitive erythrocytes and thrombocytes,
but histological sections are not favourable for blood cell identification.
After destruction of the embryo between 16 and 48 hours of incubation, Menkes and Litwac (1953) demonstrated by supravital staining
with neutral red and Nile blue that inside self-differentiating vessels of
the vascular area, yolk spheres were present.
Lemez and Rychter (1958b, c) studied blood smears from both
naturally occurring anidians and from blastoderms after early extirpation of the embryo (1958c). On the 3rd day of incubation, besides
primitive erythrocytes (Ε I), thromboblasts and thrombocytes have
been found. On the 4th day vacuolated phagocytosing histiocytes
appeared intravascularly. On the 5th day basophilic definitive erythroblasts (Ε II) were first encountered, which afterwards gradually
matured into definitive erythrocytes with round nuclei (E IIJ (Fig. 1A).
Those with oblong nuclei (E II 2 ) were relatively rare up to the 18th day
of incubation. Neutrophil leucocytes were first found on the 6th day of
incubation. No eosinophils, basophils, lymphocytes, or monocytes were
observed in smears till the 18th day of incubation. From this it follows
that differentiation of blood cells in blastoderms without circulation and
without an embryonic body takes a normal course; the autonomous
differentiation of blood corpuscles is restricted, however, to those cell
types which occur during normal development up to the 8th to 9th day
of incubation.
References
Alexander, G. V. and Schjeide, O. A. (1953). Anat. Ree. 115, 383-384.
Allison, A. C. (1960). Nature, Lond., 188, 37-40.
Ancel, P. and Houget, J. (1955). J. Embryol. 2, 290-292.
Andai, G. (1932). Arch. exp. Zellforsch. 12, 301-306.
Armstrong, M. and Ham, A. (1947). Cancer Res. 7, 481-490.
Ascarelli, A. (1895). Untersuch. Naturl. Mensch. Tiere 15, 255-276.
239
Only three investigations have been concerned with the cytology of
the blood contained in the vessels of the surviving vascular area.
Byerly (1926a, b) suffocated chick embryos after 24, 72, or 96 hours of
incubation by coating the eggs with water-glass. These eggs were then
incubated up to a maximum of 10 days of total incubation. At the end
of this period the only living portion was a peripheral ring of the
vascular area, in which, as seen in histological sections, many erythrocytes were haemolysed or binucleate (caryokinesis was obviously not
followed by cytokinesis, due to impairment of living conditions) ; the
frequent mitoses in earlier stages had disappeared completely by the
9th day. The self-differentiation of leucocytes remained uncertain.
Thrombocytes were not mentioned. Undoubtedly, Byerly observed
other cell types, especially definitive erythrocytes and thrombocytes,
but histological sections are not favourable for blood cell identification.
After destruction of the embryo between 16 and 48 hours of incubation, Menkes and Litwac (1953) demonstrated by supravital staining
with neutral red and Nile blue that inside self-differentiating vessels of
the vascular area, yolk spheres were present.
Lemez and Rychter (1958b, c) studied blood smears from both
naturally occurring anidians and from blastoderms after early extirpation of the embryo (1958c). On the 3rd day of incubation, besides
primitive erythrocytes (Ε I), thromboblasts and thrombocytes have
been found. On the 4th day vacuolated phagocytosing histiocytes
appeared intravascularly. On the 5th day basophilic definitive erythroblasts (Ε II) were first encountered, which afterwards gradually
matured into definitive erythrocytes with round nuclei (E IIJ (Fig. 1A).
Those with oblong nuclei (E II 2 ) were relatively rare up to the 18th day
of incubation. Neutrophil leucocytes were first found on the 6th day of
incubation. No eosinophils, basophils, lymphocytes, or monocytes were
observed in smears till the 18th day of incubation. From this it follows
that differentiation of blood cells in blastoderms without circulation and
without an embryonic body takes a normal course; the autonomous
differentiation of blood corpuscles is restricted, however, to those cell
types which occur during normal development up to the 8th to 9th day
of incubation.
References
Alexander, G. V. and Schjeide, O. A. (1953). Anat. Ree. 115, 383-384.
Allison, A. C. (1960). Nature, Lond., 188, 37-40.
Ancel, P. and Houget, J. (1955). J. Embryol. 2, 290-292.
Andai, G. (1932). Arch. exp. Zellforsch. 12, 301-306.
Armstrong, M. and Ham, A. (1947). Cancer Res. 7, 481-490.
Ascarelli, A. (1895). Untersuch. Naturl. Mensch. Tiere 15, 255-276.