218
LEO LEMEÈ
Parhon et al. (1956) (Fig. 4) for the period from the 11th to the 19th dayagree somewhat better, but in general, are still only about half of ours
from the 14th day onwards.
The accuracy of the method was tested by making leucocyte counts in
12 adult hens; this gave an average number of 28,600 leucocytes per
cu.mm. This number agrees closely with the average number of hen's
leucocytes given by various authors (collected by Lemez, 1955), thus
confirming the reliability of embryonic leucocyte counts.
3. Some Experiments Concerning Embryonic
Leucocytes
It might be of use to relate the results of chorioallantoic grafting to
the three periods discernible in chick embryo leucocyte numbers.
Minoura (1921) reported that new grafts take on the chorioallantois only
up to the 14th day of incubation (i.e., during the 1st period), though
beyond this stage the vascularization of the membrane is richer.
Previously implanted grafts, however, can survive the 2nd period and
persist to about the 18th day when they are destroyed by leucocytes,
especially lymphocytes (Murphy, 1916; Willier, 1924). This corresponds
to the 3rd period in the leucocyte number. We were inclined to ascribe
the inability of grafts to take on the 14th day to the higher number of
leucocytes in the 2nd period (Lemez, 1955), but experimental immunological data published in the last few years have indicated that, more
probably, the constant appearance of lymphocytes on the 14th day is
responsible. The high level of leucocytes and the relative increase in
lymphocytes at the onset of the 3rd period (18th day) undoubtedly help
to destroy the graft.
Injection of adrenal cortical extract into the allantois of chick
embryos at 13 to 15 days of incubation, caused a marked increase (about
threefold) in the number of neutrophils 24 hours after administration,
while the erythrocyte and lymphocyte counts were unaffected (Weiler
and Schechtman, 1949). A similar, fourfold increase in neutrophils after
chronic application of ACTH to chick embryos, starting on the 11th day
of incubation, was reported by Parhon et al. (1956). On the other hand,
3 0 minutes after administration of ACTH and 7 5 minutes after administration of cortisone, the granulocyte count fell rapidly, by 30% and 53% respectively . Thirty minutes after inj ection of adrenalin or insulin a decrease
in the neutrophil count by 64% and 52% occurred (Parhon et al., 1956).
From the circulating blood volume (Section II, E) and number of
leucocytes per cu.mm, the total number of leucocytes present in the
circulation was calculated (Lemez, 1955). A regular and rapid increase
in total leucocyte number throughout incubation is apparent (Fig. 5).
Because the granulocytes of hens live only about 8 days on average
(Ottesen, 1948), it is most probable that there is a cryptogenic turnover
LEO LEMEÈ
Parhon et al. (1956) (Fig. 4) for the period from the 11th to the 19th dayagree somewhat better, but in general, are still only about half of ours
from the 14th day onwards.
The accuracy of the method was tested by making leucocyte counts in
12 adult hens; this gave an average number of 28,600 leucocytes per
cu.mm. This number agrees closely with the average number of hen's
leucocytes given by various authors (collected by Lemez, 1955), thus
confirming the reliability of embryonic leucocyte counts.
3. Some Experiments Concerning Embryonic
Leucocytes
It might be of use to relate the results of chorioallantoic grafting to
the three periods discernible in chick embryo leucocyte numbers.
Minoura (1921) reported that new grafts take on the chorioallantois only
up to the 14th day of incubation (i.e., during the 1st period), though
beyond this stage the vascularization of the membrane is richer.
Previously implanted grafts, however, can survive the 2nd period and
persist to about the 18th day when they are destroyed by leucocytes,
especially lymphocytes (Murphy, 1916; Willier, 1924). This corresponds
to the 3rd period in the leucocyte number. We were inclined to ascribe
the inability of grafts to take on the 14th day to the higher number of
leucocytes in the 2nd period (Lemez, 1955), but experimental immunological data published in the last few years have indicated that, more
probably, the constant appearance of lymphocytes on the 14th day is
responsible. The high level of leucocytes and the relative increase in
lymphocytes at the onset of the 3rd period (18th day) undoubtedly help
to destroy the graft.
Injection of adrenal cortical extract into the allantois of chick
embryos at 13 to 15 days of incubation, caused a marked increase (about
threefold) in the number of neutrophils 24 hours after administration,
while the erythrocyte and lymphocyte counts were unaffected (Weiler
and Schechtman, 1949). A similar, fourfold increase in neutrophils after
chronic application of ACTH to chick embryos, starting on the 11th day
of incubation, was reported by Parhon et al. (1956). On the other hand,
3 0 minutes after administration of ACTH and 7 5 minutes after administration of cortisone, the granulocyte count fell rapidly, by 30% and 53% respectively . Thirty minutes after inj ection of adrenalin or insulin a decrease
in the neutrophil count by 64% and 52% occurred (Parhon et al., 1956).
From the circulating blood volume (Section II, E) and number of
leucocytes per cu.mm, the total number of leucocytes present in the
circulation was calculated (Lemez, 1955). A regular and rapid increase
in total leucocyte number throughout incubation is apparent (Fig. 5).
Because the granulocytes of hens live only about 8 days on average
(Ottesen, 1948), it is most probable that there is a cryptogenic turnover