/. Embryol exp. Morph. Vol. 18, 3, pp. 305-19, December 1967
With 2 plates
Printed in Great Britain
305
Observations on congenital
teratology in turkey embryos and its experimental
transmission via transplantation
ByYUTAKA TAHARA 1 & I. L. KOSIN 2
From the Department of Animal Sciences,
Washington State University, Pullman
The embryonic period of the domestic turkey is characterized by a relatively
high level of mortality (Kosin & Mun, 1960, 1965). The aim of the investigation reported below was to analyse the significance of certain changes observed
in turkey embryos doomed to die because of either congenital or experimentally
induced defects.
MATERIALS AND METHODS
The study was based on hatching eggs obtained in 1963 and 1964 from the
Broad Breasted Bronze turkey stock maintained at that time at Washington
State University for genetic investigations, and from a mass-mated flock of
non-selected White Leghorn chickens. Only such criteria as size and shape of
the egg and soundness of the shell were employed in choosing eggs for use.
The eggs were brought daily to the storage room a few hours after laying
and stored at 13-5 °C and 85 % relative humidity for 1-14 days. Following
this, the eggs were incubated at 37-5 °C and 60 % relative humidity for 1-15
days. After the desired incubation period, the fertile eggs were opened and the
embryos examined. Dead embryos were discarded; of the remaining, those
showing gross signs of abnormal development, were either preserved for
histological examination or used in transplantation experiments. The embryos
intended for the former were fixed in Bouin's solution, sectioned at 6-7 [i and
stained either with Delafield's haematoxylin and eosin or with Pollack's
trichrome.
The abnormal embryos used as tissue donors in the transplantation studies
were taken out of the shell and placed in a 0-9 % sterile saline solution. Pieces
of tissue were cut out, usually from the head region, and transplanted to the
host embryo. The latter were either 2- to 3-day-old chick embryos or 3- to
4-day-old turkey embryos. Only embryos that appeared 'normal' on gross
1
Author's address: Department of Biology, Osaka Kyoiku University, Osaka, Japan.
Author's address: Department of Animal Sciences, Washington State University,
Pullman, Wash. 99163, U.S.A.
2
306
Y. TAHARA & I. L. KOSIN
examination were used as hosts. The transplantation sites were either in the
trunk region near the wingbud, or in the head region. Transplantation was
accomplished, first, by making a small slit with a fine glass needle at the
intended site and, secondly, by inserting the graft into it (Text-fig. 1). Following
the operation, the host embryos were kept in an incubator at 37-5 °C and
60 % relative humidity and observed daily through a small glass window made
for that purpose in the shell. The histological analysis of the host-donor complex
was carried out on material prepared in a manner identical to that described
earlier.
Text-fig. 1. Scheme of transplantation. The graft (gr) from the donor (A)
was implanted into one of two sites in the host (B).
RESULTS
Part I. Morphological study
This study was based on turkey eggs only. The relevant information on the
developmental potential of the egg involved in it is summarized in Table 1.
It will be noted that three times as many abnormally developing embryos
('severely abnormal' and 'retarded') were observed in 1963 as in 1964. No
plausible explanation can be suggested for this difference. To be considered
retarded, the embryo's development had to be delayed at least two HamburgerHamilton stages behind the stage expected for it on the basis of its chronological
age.
Most of the 'severely abnormal' embryos, few of which survived beyond
the 10th day of incubation, as well as exhibiting morphological abnormalities,
were also found to be developmentally retarded. The extent of their retardation
averaged nine Hamburger-Hamilton stages.
The gross abnormalities observed in the embryos could be conveniently
arranged into four main classifications:
Malformations of turkey embryos
307
(1) Microcephalia. This, the most frequently seen abnormality, greatly varied
in its degree of severity (Text-fig. 2A-D). In general, the forebrain and the
midbrain were affected most. Furthermore, the microcephalic embryos showed
asymmetrically developing eyes; one was invariably smaller than the other
(Plate 1,fig.C).
Table 1. Incubation data, turkeys
1963
1964
i
Eggs
Incubated
Fertile
Embryos
Normal
Severely abnormal
Retarded
Dead
r
n
/o
n
408
288
—
1610
1271
—
71
199
44
45
0
69
15
16
—
1081
77
60
53
85
6
5
4
0/
/o
79
(2) Twisted body axis. In the affected embryos, the normal alignment of the
somite region was distorted. In extreme cases (Text-fig. 2 D) the outline of the
embryo assumed the shape of a question mark. Somite development on either
side of the median line was often asymmetrical, i.e. the number of somites on
the right and left side did not match.
(3) Duplication. In this case the asymmetrical development of somites was
the rule (Text-fig. 2 E). Twins have been observed pointing either in the same
direction or, less frequently, in the opposite direction.
(4) ' Vesicular Blastoderms'. This was an example of extreme deformity, in
which the embryo superficially, at least, appeared to be a complex of several
vesicles (Text-fig. 2 F). On histological examination, such embryos revealed
evidence of differentiation into embryonic and extra-embryonic regions, although
they always lacked development of the neural tube.
In all four types mentioned above, the embryo proper could always be
identified in eggs of more than 3 days of incubation. By contrast, a type of
development reminiscent of 'anidian' embryos (according to Harrison & Klein
(1954), first described by Broca in 1862) was occasionally encountered, in which
tissue prohferation continued without any clear-cut distinction between the
embryonic and extra-embryonic region.
In studying the histo-pathological aspects of abnormal turkey embryos,
certain characteristic patterns were observed. Three specimens representative
of the abnormalities involved will illustrate this point.
Embryo 430-15. This microcephalic embryo was discovered in an egg incubated
for 4 days. Numerous lesions of necrotic cells were found scattered throughout
the embryo, particularly in the anterior half. Cell necrosis was widespread in
308
Y. TAHARA & I. L. KOSIN
the brain, heart, notochord, pharyngeal epithelium, mesenchyme, and certain
epidermal regions. Characteristically, there was evidence of mass disintegration
in the ventral wall of the neural tube (Plate 1, figs. A, B). This was accompanied
by pronounced cell necrosis. By contrast, the lateral and dorsal portions of
the neural tube only occasionally evidenced necrotic cells.
The epidermis was largely normal except in those areas where deep infolding
brought it into contact with the affected region of the neural tube (Plate 1,
fig. A). Such tissue-to-tissue contact, as a factor facilitating the spread of tissue
Text-fig. 2. Diagrammatic representation of the more frequent developmental
abnormalities. A, B, microcephalic 96 h embryos; C, microcephalic 120 h embryo.
Note distortion in the somite area, reversed orientation of the embryo, and delayed
closure of the amnion (arrow); D, microcephalic 168 h embryo. Note exaggerated
torsion of the body axis; E, nearly complete duplication in a 72 h embryo. Note
grossly abnormal development of the head region; F, vesicic-like embryo after
192 h of incubation. One of the vesicles (arrow) pulsated at the time of the
examination.
and cellular disintegration, was seen in most of the abnormal embryos examined
and therefore was deemed to be significant in the general syndrome of developmental abnormality and eventual death of moribund turkey embryos.
Embryo 489-01. The entire central nervous system and its associated parts of
this 5-day turkey embryo showed colonies of necrotic cells with severe lesions
in the mid- and hind-brain region. Again, as in the previous specimen, the
cellular disintegration was limited to the ventral and ventro-lateral aspects of
the affected structure. The asymmetry of the eyes was extreme (Text-fig. 3;
Plate 1, fig. C). The incidence of cell necrosis was higher on the affected, left,
side of the optic complex. The visceral arches were also involved (Plate 1,
Malformations of turkey embryos
309
fig. D). No lesions were seen in the trunk region, although, again, evidence of
cell necrosis was widespread, including the mesenchyme cells surrounding the
Wolffian ducts, notochord, sclerotome, somites, coelom, gut, and dorsal aorta
(Plate 1, fig. E). The cells which constitute the principal morphological component of each of these tissues (e.g. the myoblast of the somites, the epithelial
lining of the gut, the notochordal cells of the notochord) did not, however,
exhibit any signs of lysis. The wingbuds were affected; the necrotic cells were
Wd
Fig. 3
Fig. 4
Text-fig. 3. Semi-diagrammatic drawing of the same area (the midbrain and the
eyes) as that presented in Plate 1 C, showing the distribution pattern of necrotic
cells. The latter are represented here by large dots; small dots signify the presence
of cell debris.
Text-fig. 4. Semi-diagrammatic drawing of a section through the wingbud region
of embryo 489-01. Note large concentration of necrotic cells, represented by large
dots, in the mesenchyme immediately under the apical ectoderm (ae) and also
adjacent to the urogenital system, ne, mesonephrogenic mesenchyme; Wd, Wolffian
duct.
scattered not only in the mesodermal component of the region but in the apical
ectodermal ridge as well (Text-fig. 4).
Embryo 497-19. In this 2-day 'anidian' embryo, the epiblast consisted of
a thin mantle of cells closely adhering to one another. By contrast, the hypoblast
cells were more loosely associated, intermingling in the lower stratum with
yolk granules. None of the epiblast cells, but many of the hypoblast cells, were
necrotic (Plate 1, fig. F).
The cells within degenerative lesions were judged, on the basis of fixed
preparations, to go through a series of regressive changes leading to necrosis.
The cytoplasm in the pre-necrotic cells shrank from the nuclear membrane, in
310
Y. TAHARA & I. L. KOSIN
some cases giving rise to a characteristic 'halo' effect. These clear spaces were
either round or ovoid in shape and varied in size. In other cells, haematoxylinstained granules, small in size, were seen scattered throughout the 'halo' area.
On the other hand, a portion of the extra-nuclear region within the 'halo' area
of some of the affected cells stained deeply with eosin, presenting the appearance
of an 'inclusion body' (Plate 2, fig. A).
Most nuclei were undergoing regressive changes which eventually led to
complete karyorrhexis (Plate 2, fig. B). In such cases, the nuclear membrane
was no longer visible and numerous small particles that showed affinity for
nuclear stains were scattered in the space normally occupied by the nucleus.
Some nuclei retained their identity. The latter usually stained with eosin.
Part II. Transplantation study
In the control series, the host and the donor organisms were carefully selected
to exclude any embryos that deviated, on gross examination, from the normal.
All four possible combinations, involving turkey and chicken embryos as host
and donor, were made. Ten such cases were analyzed in detail in this series.
In the experimental series, on the other hand, the donor was always an abnormally developing turkey embryo; the host was either a turkey or a chicken
normal embryo. In 10 of the 12 specimens involved, the host was a chicken
embryo, in two a turkey embryo. In both series, control and experimental, the
donors were searched for the presence of necrotic cell foci in selected tissues.
In the control series, there was no evidence of increased frequency of necrotic
cells, either in the graft or the host. Some cellular necrosis, of course, can always
be observed in otherwise normally developing avian embryos (Saunders, 1966).
In this respect at least, neither the graft nor the host proved to be in any way
exceptional. Degenerative lesions were also absent (Plate 2, fig. C). By contrast,
in the experimental series, the presence of necrotic foci was always in evidence
PLATE 1
Figs. A, B, E. Transverse sections of turkey embryo 430-15. Incubation time 96 h. Figs. C,
D, F. Transverse sections of turkey embryo 489-01. Incubation time 120 h.
Fig. A. Section at the level of the anterior portion of the midbrain. Note incomplete formation
of the neural tube dorsally. x 146.
Fig. B. Section at the level of the posterior portion of the midbrain. Note tissue breakdown
in the ventral region of the neural tube. The latter observation also applies to A above, x 146.
Fig. C. Section at the level of the midbrain and eyes. See text for explanation. Also cf.
Text-fig. 3. x 138.
Fig. D. Section at the level of visceral arches. See text for explanation.
Fig. E. Section at the level of the gut. Numerous necrotic cells can be seen (a few are pointed
out, by arrows), scattered in the epithelial lining of the stomach, x 624.
Fig. F. Anidian-type blastorm, 479-19. Note necrotic cells (arrows) scattered in the hypoblast. The epiblast is to the right, x 624.
/. Embryol. exp. Morph., Vol. 18, Part 3
Y. TAHARA & I. L. KOSIN
PLATE 1
jacing p. 310
/. Embryol. exp. Morph., Vol. 18, Part 3
Y. TAHARA & I. L. KOSIN
PLATE 2
facing p. 311
Malformations of turkey embryos
311
in the donor and, usually, in the graft as well as in the host. The degree of
severity of this condition varied (Table 2).
The presence of a peculiar intracellular 'inclusion body' (already mentioned
in part I) was also observed in cells within necrotic lesions. Their distribution
was largely limited to the epithelial lining of the neural tube, the lens, retina
Table 2. Transplantation experiments. Experimental series:
abnormal donor-normal host
Severity of reaction in the
Donor
Turkey donor and host
T-T2*
T-T7
Turkey donor-Chicken host
T-CH5
T-CH8
T-CH29
T-CH31
T-CH34
T-CH38
T-CH39
T-CH44
T-CH50
T-CH52
Graft
Host
2
10
* Host specimen number.
± Indicates cases in which a trace of cellular necrosis was found. + +, + + + indicate
cases in which degenerative lesions and cellular necrosis were found (with increasing severity
in this order).
PLATE 2
Fig. A. Section through the mesonephric duct of a 'congenitally' microcephalic turkey
embryo. Several 'inclusion' bodies (arrows) can be seen within the cytoplasm of epithelial
cells, x 624.
Fig. B. Section through the trunk region of a 5-day turkey embryo (489-01), showing various
stages of necrosis, particularly in the notochord (nt). x 624.
Fig. C. Section of the control specimen C-CH6. No evidence of organ lesion can be detected
either in the graft (which runs through the central area of the section) or in the host. The
neural complex (with active mitosis detectable at a higher magnification) can be seen in
the upper part of the graft, x 210.
Fig. D. Section of the specimen, T-CH50, through the brain region (br). Note numerous
necrotic cells in the graft (gr) and in the brain wall of the host embryo, as well as signs of
general disintegration, x 210.
Figs. E, F. Frontal sections of two regions, anterior (E) and posterior (F), of the right
mesonephros in the specimen T-CH31. Cells in E appear to be normal (containing only two
necrotic cells in the figure, arrows), while in F more than 30 are necrotic. Arrows point to
some of them, x 400.
312
Y. TAHARA & I. L. KOSIN
and mesonephric tubules. Occasionally, some were found in the epidermis and
in the amnion.
Because in the experimental series the reaction of the host to the implant
varied widely in its histological aspects, several typical examples of it will be
described below.
T-CH50. The donor was a 5-day-old microcephalic turkey embryo which
had numerous necrotic cell foci throughout its body. The graft, taken from the
Text-fig. 5. Semi-diagrammatic drawing of host chick embryo T-CH50 24 h after it
was implanted with a graft (gr) from a microcephalic 5-day turkey embryo. The
host embryo shows unmistakable signs of incipient microcephaly.
head region of the embryo, consisted mainly of neural tissue and contained
numerous necrotic cells, and was transplanted to the corresponding region of
a 2-day-old chicken embryo. Twenty-four hours later, it became evident that
the host was developmentally retarded, showing an early stage of microcephaly
(Text-fig. 5). In the host, the graft was in contact with the mesenchyme of the
head region (Plate 2, fig. D). The cells of the latter tissue as well as that located
at some distance from the graft were affected, showing gross signs of cell
lysis. The only tissue that remained completely unaffected was the epidermis.
When grafting was performed on older embryos, e.g. 3-day and 4-day turkey
embryos, the distribution pattern for necrotic cells became more specific.
Malformations of turkey embryos
313
A typical example of this is afforded by a host specimen T-CH31. This
3-day-old chicken embryo received a graft just under the skin, near the right
wingbud. The graft was taken from a 5-day-old microcephalic turkey embryo.
Extensive lesions of necrotic cells were found throughout the latter's body.
Twenty-four hours after implantation, the host showed signs of retardation and
Text-fig. 6. Semi-diagrammatic representation of the distribution pattern of necrotic
cells in specimen T-CH31 48 h after the graft was implanted. The host was a 3-day
normal chick embryo; the donor a 5-day severely microcephalic turkey embryo.
Dots represent the concentration of necrotic cells: the more dots, the greater the
concentration of these cells. The latter were located and counted through three
serial sections. A, visceral region; B, eye; C, stomach and liver; D, tailbud
region; E, mesonephros; F, wingbud; G, trunk region; H, otic vesicle, aer, apical
ectodermal ridge; ao, aorta; bd, bile duct; gr, graft; liv, liver; me, mesonephric tubule;
mes, mesenchyme; so, somite; st, stomach; tg, post-anal gut; thy, thyroid; va,
visceral arch.
314
Y. TAHARA & I. L. KOSIN
of incipient microcephalia. At 48 h cellular necrosis in the host was widespread:
necrotic cells were found in the area just adjacent to the graft site, as well as in
the brain region of the neural tube, in optic and otic vesicles, mesonephros,
mesenteries, sclerotome, fore- and hind-limb buds, and in the digestive tract
and tailbud. Only a few necrotic cells were found in the skin, heart, notochord,
myotomes, liver, pancreas, and blood vessels. The eosinophilic 'inclusion body'
was occasionally encountered in the affected tissue. An attempt to present, in
diagrammatic form, the distribution pattern of the affected areas in the embryo
is made in Text-fig. 6. In it, severity of the necrotic condition is indicated by
stippling—the greater the severity of necrosis, the denser the stippling. Photographs of selected areas affected by necrosis are shown in Plate 2, figs. E
and F.
Text-fig. 6 reveals that the frequency of the necrotic cells varied along the
cephalo-caudal axis. Within the CNS, there were two peaks, one at the level
of the telencephalon and optic vesicles, and the other in the tip of the tailbud.
Similarly, two density peaks are apparent in the mesenchyme cells of the digestive
tract, one in the region of the proventriculus, and the other at the level of the
post-anal gut. The meso- and meta-nephric mesenchymal cells, occupying the
caudal part of the primordium, were more affected than those located anteriorly
(cf.Plate 2, figs. E and F).
A similar pattern of cellular necrosis following grafting was observed in
four other hosts, T-CH8, 34, 39 and 44 (see Table 2). In general, most of the
necrotic cells were in mesenchymal tissue, which is, of course, at this stage
relatively undifferentiated; by contrast, fewer necrotic cell foci were seen in the
more differentiated epithehal tissue. The site of the graft (e.g. wingbud area in
T-CH31 and cavity of the midbrain in T-CH8) did not appear to affect the
pattern of subsequent damage to the host embryo.
In the third type of donor-host interaction, despite clear-cut histological
evidence of severe necrotic conditions in the donor, the host was found to be
only slightly affected. This was true for T-CH5, 29, 38, and T-T7 (see Table 2).
The last specimen can serve as an example. The donor was a malformed
4-day turkey embryo. Histologically, it showed the presence of widespread severe
necrotic lesions. The graft was taken from its head region and implanted into
the wingbud region of a 4-day turkey embryo. Fifty hours after the operation,
the host embryo was examined and prepared for histological analysis. It showed
no gross signs of incipient death; only a few necrotic cells could be identified
in it. The graft was relatively unaffected by the otherwise generahzed condition
of cellular necrosis of the donor. Instead, when examined in situ in the host,
the graft revealed the presence of numerous macrophages. These cells were
particularly abundant near the outer surface of the neural tube.
'Inclusion bodies' were detected in at least one of the specimens in this group
(T-CH38). These inclusions stained reddish orange with Pollack's trichrome.
Malformations of turkey embryos
315
DISCUSSION
Evidence of developmental disturbance in non-operated turkey embryos
could usually be detected by histological means early in embryogenesis.
Examination of such preparations at suspected incipient sites of damage more
often than not revealed widespread lesions of necrotic tissue in embryos less than
48 h of age. We suggest that most if not all embryos so affected die within the
first 7 days of incubation. This is deduced from the fact that during this stage
of development the various organ systems are laid down and, hence, any serious
deviation from normality at this time would likely lead to death. Furthermore,
the ease with which early embryos can be affected by various teratogenic agents
and treatments supports this view.
The fact that the evidence pointing to impending defects appears so early
in development suggests that the causes of these conditions reside within the
embryo, being in a sense 'congenital' and not caused by the embryo's immediate
micro-environment. Support for this view was obtained from another line of
evidence. A complete record was kept in 1963 and 1964 of the frequency of
malformations according to the source of egg, i.e. the hen that laid it. Thus, in
1964, hen no. 441 during the observation period produced, in all, two microcephalic and four normal embryos. On the other hand, her full-sib, hen no. 445,
laid 12 fertile eggs, all of which gave rise to normal embryos. The mother of
these two birds, hen no. 439, in the 1963 experimental period, laid 20 eggs, of
which eight were infertile. The balance yielded seven embryos that died within
the first 10 days of incubation, and five produced normal poults. Extensive
malformation characterized the affected embryos. Except for the evidence
obtained in the studies from transplantation experiments, all of the relevant data
would point to heredity as a possible underlying cause for the observed developmental abnormality. In our opinion, however, many of these and similar defects
so prevalent in our stock as well as in other stocks of the domestic turkey are
induced by a distinct agent, or agents, which is already present in the egg at
the time the latter is laid.
Extensive experimental evidence is available to show that malformations
can be produced in avian embryos by exposing them to specific conditions at
an appropriate time. Thus, physical and chemical agents can produce malformations in chick embryos (e.g. Grodzinski, 1933, 1934; Paff, 1939; Harrison &
Klein, 1954; Ancel, 1958; Rolf, 1959; Landauer, 1960; Olin, 1960; Lanot, 1963;
Boone, Hammond & Barnett, 1964; Grabowski, 1961, 1963, 1966). Introducing
certain viruses into eggs can cause a wide range of malformations in the embryo.
For example, Blattner & Williamson (1951) and Robertson, Williamson &
Blattner (1955) reported that inclusion bodies were among the characteristic
features of cellular necrosis observed in chick embryos inoculated some 24 h
earlier with Newcastle virus. Hamburger & Habel (1947) demonstrated that
the teratogenic effect of influenza-A virus introduced into chick embryos
20
JEEM l8
316
Y. TAHARA & I. L. KOSIN
(development of malformations and death) could be evoked by transplanting
tissue from affected embryos to normal ones.
The results of our transplantation studies demonstrate that our 'dead cell
syndrome' could be transmitted by a tissue graft from a visibly affected,
' congenitally' malformed embryo, to embryos which on gross examination
prior to transplantation showed no signs either of disease or of abnormal
development. In our experience, the syndrome also included the presence of
intracellular but extra-nuclear eosinophilic structures which, for want of a
better term, we have designated as inclusion bodies. Similar transplantations
from apparently 'normal' embryo donors into likewise 'normal' hosts never,
in our experience, produced this syndrome.
Both cytoplasmic and intra-nuclear inclusion bodies associated with specific
viruses have been described in the literature (e.g. Lucas, 1951; Love, Fernandes
& Koprowski, 1964).
It would be futile at this time to speculate extensively on the nature of the
agent or agents responsible for the observed phenomenon of transmissibility
of disease in our early turkey embryos. Viral involvement suggests itself. It
should be pointed out, however, that the history of our stocks lacks any evidence
of either chronic or acute widespread pathological conditions attributable to
virus. Moreover, neither the birds which supplied eggs for the present study,
nor their predecessors, were ever subjected to vaccination. (The latter could,
of course, serve as a possible source of a virus, passed on from generation to
generation.) Only healthy birds, by gross examination normal in every respect,
supplied the hatching eggs used. If viral infection was involved in the stock, the
agent must have been endemic in the experimental populations and possibly
in all domestic turkeys.
The differential susceptibility of embryonic tissues of normal host embryos
to the graft-transmitted necrotic effect of the affected donor embryos calls for
some brief comments. An example of this has been diagrammatically illustrated
in Text-fig. 6. In turkey embryos, besides cells of the rapidly evolving nervous
system, the mesenchymous cells, still relatively undifferentiated, were more
susceptible to induced necrosis than cells found in well-differentiated epithelial
complexes. The site of the graft in the host had no effect on the ultimate
distribution, within the latter, of the subsequently arising necrotic foci, corroborating a similar observation by Hamburger & Habel (1947). The latter
investigators worked with influenza-A type virus as the teratogenic agent in
initially normal, healthy chick embryos. It would appear that it is the availability
of rapidly developing systems containing a preponderance of undifferentiated
cells that determine in the host the locale of the necrotic foci rather than the
actual physical pattern of distribution of the responsible agent or agents
per se.
Embryonic tissue interrelations in the production of abnormalities in avian
embryos is indeed relevant to the origin of malformations observed by us in
Malformations of turkey embryos
317
turkey embryos (cf. Gruenwald, 1947; Zwilling, 1956; Fraser, 1960). According
to Spratt & Haas (1960, 1965), the hypoblast cells of the unincubated chicken
blastoderm constitute a gradient system necessary for subsequent normal
embryogenesis. In their experience, a major disturbance of such a system led
to malformation in embryos. In the present study, evidence has been obtained
(e.g. embryo 497-19) pointing to the involvement of the hypoblast, resulting
in the failure of the embryonic axis to form. Perhaps the origin of at least
certain other teratologies, such as twinning, can be accounted for on the same
basis.
SUMMARY
1. Abnormally developing Broad Breasted Bronze (turkey) embryos were
subjected to morphological and histological analysis. Certain malformations
such as microcephaly, twisted body axis, partial twinning, failure of the neural
tube to close, and anidian embryos were the most frequently encountered.
Histological examination of such malformed embryos usually revealed the
presence of foci of necrotic cells scattered throughout the embryo's body. When
an organ showed such a lesion, similar necrotic foci could usually be found in
tissues in direct contact with the affected organ. The cytoplasm of cells in these
lesions often carried eosinophilic 'inclusion bodies'.
2. To study the distribution pattern of the necrotic foci, series of tissue
transplantations from malformed turkey embryos into apparently normal
turkey and chicken embryos were carried out. Cell necrosis and eosinophilic
inclusions were found in the donor specimens of the experimental series.
Subsequent to transplantation, the originally normal host embryos proceeded
to develop, in varying degree, both morphological and histological symptoms
associated with the donor's teratology. No such syndrome was observed in the
control transplantation series, involving normal donors and hosts.
3. Evidence has been presented for the existence of differential susceptibility
of embryonic tissues to induced necrosis; nervous tissue and the mesenchyme
showed highest susceptibility.
4. The possible significance of the demonstrated transmissibility of the cell
necrosis syndrome to embryonic development of the domestic turkey has been
discussed.
RESUME
Observations sur la te'ratologie congenitale d? embryons de dinde
et sa transmission experimental par transplantation
1. On a fait Panalyse morphologique et histologique d'embryons de dinde
a developpement anormal (race 'Broad Breasted Bronze'). Certains types de
malformations, tels que microcephalie, torsion de l'axe du corps, gemellite
partielle, absence de fermeture du tube neural, embryons anidiens, ont ete
le plus frequemment rencontres. L'examen histologique de tels embryons
318
Y. TAHARA & I. L. KOSIN
malformes a revele la presence de foyers de cellules necrotiques disperses dans
tout le corps de l'embryon. Quand un organe presentait une telle lesion, des
foyers necrotiques semblables ont pu etre trouves dans les tissus en contact
direct avec 1'organe affecte. Le cytoplasme des cellules de ces lesions renfermait
souvent des 'inclusions' eosinophiles.
2. Pour etudier le mode de repartition des foyers de necrose, on a realise
des series de transplantations de tissus d'embryons malformes dans des embryons
apparemment normaux de dinde et de poulet. On a trouve des necroses cellulaires et des inclusions eosinophiles dans les specimens donneurs de la serie
experimental. Apres la transplantation, les embryons notes originellement
normaux ont developpe, a des degres varies, des symptomes a la fois morphologiques et histologiques associes a la teratologie du donneur. On n'a pas
observe de tel syndrome dans la serie de transplantations temoins, comprenant
des donneurs et des notes normaux.
3. On a fourni des arguments en faveur de l'existence d'une sensibilite
differentielle des tissus embryonnaires a Fegard de la necrose induite; le tissu
nerveux et le mesenchyme ont montre la sensibilite la plus grande.
4. On a discute la signification possible de la transmissibilite demontree du
syndrome de necrose cellulaire et ses rapports avec le developpement embryonnaire de la dinde.
This investigation was supported in part by Research Grant 5544 from the Division of
General Medical Sciences, U.S.P.H. Service. This is Scientific Paper No. 2946, College of
Agriculture Research Center, Pullman, Project no. 1255.
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{Manuscript received 25 April 1967)