1. The increase in wet weight of the host spleen following implantation of competent chick, juvenile or adult chicken spleen has been shown to be paralleled by increases in dry weight and in content of RNA, DNA, and protein.

  2. No increase in the spleen-weights of the hosts was found when non-competent spleen cells from chick embryos or 1-day-old chicks were used as donor.

  3. The onset of immunological competence with respect to this transplantation reaction has been shown to occur at about 5 days post-hatching when the spleens were implanted into embryos at 8 days of incubation and the host spleens removed 10 days later.

  4. The ability of chicken spleen cells to evoke hepatomegaly and splenomegaly of the embryo hosts increased with age and was greatest after 21 weeks of age. Sometimes a reduction in whole body-weight of the embryo hosts also occurred.

  5. Although no sex differences in host spleen-weight were observed when 8– 15-day-old male chick spleens were used as grafts, a significant increase in female host liver- and spleen-weights (compared with those of the male hosts) was noted when 8–21-day-old female chick spleens were used as grafts.

  6. Spleen cells from male chickens of 6–17-weeks old did not produce much greater splenomegaly than those from young chicks and there were no sex differences between the host embryo spleen-weights. However, when female spleen tissue from 6-to 20-week-old chicks was used as graft a significant increase in the hepatomegaly and splenomegaly of the female hosts above those in the male hosts was observed.

  7. No sex differences were obtained in embryo host spleen-weights when small implants of adult male or female spleen cells were used as grafts.

  8. Thymus, liver, and bone-marrow from competent donors have been found to be nearly as effective as spleen in producing splenomegaly of the embryo hosts.

When implants of spleen from mature homologous chicken are placed on the chorio-allantoic membranes of chicken eggs, certain of the adult cells rapidly invade the vascular system of the host (Dantchakoff, 1918). Some of these cells colonize the spleen of the host embryo (Biggs & Payne, 1959; Ebert, 1959; Simonsen, 1957) and after a short latent period these adult cells proliferate in the host spleen under the stimulus of continuous exposure to the individual specific foreign antigens of the host. The resulting splenomegaly of the host embryo is generally recognized to be due to the proliferation of these immunologically competent cells. However, the possibility of enhanced mitotic division of spleen cells of the embryonic host being also partly responsible for the splenomegaly has been suggested by Biggs & Payne (1959). This type of transplantation effect has been termed the ‘graft versus host’ reaction (Simonsen, 1957) of which the initial symptoms are splenomegaly and hepatomegaly of the host. These are followed in some cases by the more drastic symptoms of runt disease (Billingham & Brent, 1959; Duyff, 1929; Mun, Kosin, & Sato, 1959).

In 1951 Ebert related the appearance of certain antigens during the development of the chick embryo to a small but statistically significant increase of host spleen-weight when spleens from embryos of at least 14 days of incubation were used as grafts. The spleens were implanted on to the chorio-allantoic membrane of homologous chick embryos at 8 days of incubation and the host spleen removed 10 days later. This finding is not in accord with the work of Dantchakoff (1918), Delanney (1961), and Solomon (1960a): these workers found that under similar conditions to those used by Ebert (1951), splenic implants from chick embryos of any age did not produce splenomegaly in the host embryo. Under these conditions of implantation Solomon (1960a) showed that there was a sudden onset of the ability to evoke splenomegaly of the host when the donor spleens were taken from chicks which were 5 days old post-hatching. Simonsen (1957) had previously shown that no splenomegaly occurred when blood from chicks less than 11 days old post-hatching was injected into 18-day-old chick embryos and, more recently, Isacson (1959) obtained similar results with intravenous injection of spleen cells into 14-day-old embryo hosts.

This paper presents data on the onset and maturation of the ability of small implants of certain chicken cells to evoke splenomegaly in the embryonic host and the effect of age and sex of the donor and host on the initial stages of the graft versus host reaction as shown by splenomegaly is examined.

White Leghorn chickens and eggs supplied by Withers & Son (Appleby Farm Ltd., Kent) were used in this investigation. Brown Leghorn fowls were obtained from the Poultry Research Centre, Edinburgh. Eggs were incubated in a Westernette incubator at 99° F. for 8 days. Spleens were taken from young chicks (2–21 days post-hatching), juvenile chickens (6–20 weeks old), and adults.

Aseptic techniques were used for the removal of the tissue from the donor and the implantation and injection methods. Implants weighing about 5 to 10 mg. (wet weight) were prepared by cutting up the tissues in a Petri dish and then gently macerating the pieces with curved forceps. The method of implantation was essentially that described by Willier (1924). A slit was cut into the shell above the air-sac and a triangular window (1×1×l cm.) was cut in the shell (with a cutting disk on a dental drill) at a point where a large vein of the chorioallantoic membrane had been previously located by candling. The shell membrane was punctured, the chorio-allantoic membrane dropped, and the macerated implant placed on a vein of the chorio-allantoic membrane. A sterilized cellophane square was placed over the window which was sealed with paraffin wax containing some Sudan red dye. The eggs were placed in an incubator with the window uppermost and were then incubated for a further 10 days at 99° F. Embryos were removed at 18 days of incubation, dried on paper, and weighed to the nearest 0·1 g. Livers and spleens were removed and placed on moist lint and the host embryos sexed. The gall-bladders were removed from the livers, and the latter were weighed to the nearest mg.; spleens were weighed to the nearest 0·1 mg. Each experiment included sham-operated controls which underwent the same operation as the experimental eggs except that they had no tissue implanted. Chicks used as donors were sexed by examination of their gonads. Unless stated otherwise, spleens from White Leghorn donors were implanted on to 8-day-old White Leghorn host embryos and the livers and spleens removed 10 days later, i.e. at 18 days’ incubation.

Ribonucleic acid (RNA), deoxyribonucleic acid (DNA), and protein were estimated by extraction and colorimetric methods similar to those used in previous work on the chick embryo (Solomon, 1957a). Spleens were homogenized in ice-cold phosphate buffer, pH7 (1 g./l5 ml.), and a small fraction of this was retained for protein estimation. The remainder of the homogenate was brought to 0-2 M perchloric acid (PCA) with 1-0 M PCA and stirred for 15 minutes at 4° C. After centrifugation, the supernatant containing acid-soluble nucleotides was discarded and the pellet resuspended in 1·0 M PCA (approx. × pellet volume) and incubated at 70° C. for 20 minutes. After centrifugation and a further similar extraction and centrifugation the pooled supernatants were retained. Protein was determined by the method of Sutherland, Cori, Haynes, &lsen (1949), DNA was measured by the method of Burton (1956), and RNA was measured by the orcinol method of Ceriotti (1955), omitting the isoamyl alcohol extraction, but with a preliminary hydrolysis of the extract with 0·1 M NaOH at 100° C. for 15 minutes to remove interfering hexose compounds. Standards were bovine serum albumin and chick-liver RNA and DNA.

Splenomegaly of the host as a proliferation of cells

There is abundant histological evidence that the increase of host spleen-weight in the graft versus host reaction is due to cellular proliferation (e.g. Dantchakoff, 1918; Ebert, 1951; Biggs &Payne, 1961). There is also evidence that the increase in wet weight is accompanied by an increase in total nitrogen (Ebert, 1954). As Anreini, Drasher, & Mitchison (1955) found that a slight increase in the RNA to protein ratio apparently accompanied antibody production in mice, I oth RNA and DNA as well as protein and dry weight have been measured in this work. The RNA, DNA, and protein content was determined in host spleens from some of the experiments to be described later. These included experiments in which the hosts received grafts of spleen from 15-to 20-day-old embryos, from 8-to 21-day-old chicks, and from adult fowls of20-78 weeks old. Each determination of nucleic acids and protein was made in duplicate on the extract from 100 to 200 mg. host spleen. Table 1 shows that the RNA, DNA, and protein per g. wet weight remained constant in both the sham-operated control host spleens and in the non-enlarged and enlarged experimental spleens. These results do not agree with those of Ebert (1954), who found that the DNA content per g. wet weight of the host spleens bearing adult chicken spleen implants showed a statistically significant 30 per cent, decrease below that of the controls. There was no change in the RNA/protein ratio in this work. Dry weights were determined by drying the spleen overnight at 90° C.; the dry weight, expressed as a percentage of the wet weight, was 18·3 per cent, for 7 control spleens (mean wet weight 15·6 mg.) and 19·4 per cent, for 10 selected enlarged spleens (mean wet weight 61·8 mg.) from hosts which had been implanted with adult spleen. It can be concluded that the increase in wet weight of the spleens is due to cellular proliferation. When spleen cells from competent fowls were implanted, the enlarged livers frequently appeared green due to bile stasis and the gall-bladders were shrunken; enlarged spleens usually had a normal appearance except that occasionally they showed marked white nodules.

Table 1.

RNA, DNA, and protein content of host spleens from chick embryos grafted with splenic implants from embryo, chick and adult donors

RNA, DNA, and protein content of host spleens from chick embryos grafted with splenic implants from embryo, chick and adult donors
RNA, DNA, and protein content of host spleens from chick embryos grafted with splenic implants from embryo, chick and adult donors

Comparison of the effectiveness of spleen, liver, bone-marrow, and thymus in eliciting splenomegaly

Several tissues of the chicken have been found to evoke the graft versus host reaction. Table 2 shows a few experiments in which two or three tissues were taken from the same donor and small implants of each tissue were then used in the 8–18-day White Leghorn host system. The active cells are distributed in the thymus, liver, and bone-marrow as well as in the spleen; all these tissues are rich in reticulo-endothelial cells in the chicken. In the White Leghorn donor to White Leghorn host experiments in Table 2 liver tissue from 3 donors produced a host spleen mean weight of 27·3±2·9 mg. (19 hosts), bone-marrow from 2 donors produced a host spleen-weight of 28·5±3·3 mg. (17 hosts), thymus from one donor produced a mean spleen-weight of 31·9 ±7·1 mg. (7 hosts), and spleen from 5 donors produced a host spleen-weight of 34·4±3·2 mg. (63 hosts). There was no significant difference between any of these mean weights.

Table 2.

Comparison of the effectiveness of spleen, liver, thymus, and bone-marrow from juvenile and adult donors in eliciting splenomegaly

Comparison of the effectiveness of spleen, liver, thymus, and bone-marrow from juvenile and adult donors in eliciting splenomegaly
Comparison of the effectiveness of spleen, liver, thymus, and bone-marrow from juvenile and adult donors in eliciting splenomegaly

Onset of competence in White Leghorn spleens implanted into White Leghorn embryos

Solomon (1960a) reported that chicks up to 4 days post-hatching were incapable of producing splenomegaly and that there was a tendency for greater increases of spleen-weight to occur in female hosts rather than in the male hosts. These results are shown in full in Table 3 which gives results from one hatch of White Leghorn chick donors. In this case the onset of competence to produce splenomegaly is shown at 5 and 6 days post-hatching in the female hosts. In the experiment in which 6-day-old chick spleens were used as donors there was a statistically significant difference (P = 0·05) in the spleen-weights of the male and female hosts; the same tendency was shown in the experiment with 8-dayold chick donors. However, there was no difference between the male and female hosts when 7-day-old chicks were used as donors. The time of onset of competence of donor chick spleen cells to produce splenomegaly has not been so well defined in other experiments. This has been due to a lower proportion of enlarged spleens and consequently a small increase in the mean weight of the host spleens. For example, in one experiment spleens from 10-day-old chick donors produced only one enlarged spleen of 89 mg. out of 25 within the normal range. Similarly, in earlier experiments (Solomon, 1960a), 2-day-old chicks had produced one enlarged host spleen of 60 mg. out of 19 others which had been within the normal (control) range of 5–25 mg., and 5-day-old chicks had produced only one enlarged spleen of 38 mg. in 23 spleens within the normal range.

Table 3.

Onset of the competence of chick spleen to elicit splenomegaly

Onset of the competence of chick spleen to elicit splenomegaly
Onset of the competence of chick spleen to elicit splenomegaly

It was desirable to ascertain whether any small sex differences occurred when incompetent cells were used as donor tissue. Table 4 shows some small-scale experiments with 15-, 18-, and 20-day chick embryo donors supplying small implants of spleen for the 8–18-day period of host incubation. No increase in spleen-weight and no sex differences in the mean spleen-weights were observed. The sex differences in host spleen-weight which were found when spleens from unsexed chick donors were used (Table 3) were examined more fully in separate experiments using male or female donors. Table 5 shows the results of 3 experiments with male chick donors of from 8 to 15 days post-hatching. Most of the host spleen- and liver-weights showed statistically significant increases compared with the controls; no sex differences in host spleen-weight were found. When female chicks 8–21 days post-hatching were used as donors, the 8-day-old chick spleens did not elicit hepatomegaly or splenomegaly in the hosts (Table 6). However, 11 -day-old female chick donors produced a highly significant hepatomegaly and splenomegaly in the host. Although there were no significant sex differences in the host liver- and spleen-weights within the individual experiments, the total liver- and spleen-weights from all 4 experiments showed a statistically significant (P = 0·05) increased liver- and spleen-weight in the female hosts.

Table 4.

Inability of embryonic spleen to elicit splenomegaly

Inability of embryonic spleen to elicit splenomegaly
Inability of embryonic spleen to elicit splenomegaly
Table 5.

Ability of male chick spleen implants to elicit splenomegaly

Ability of male chick spleen implants to elicit splenomegaly
Ability of male chick spleen implants to elicit splenomegaly
Table 6.

Ability of female chick spleen implants to elicit splenomegaly

Ability of female chick spleen implants to elicit splenomegaly
Ability of female chick spleen implants to elicit splenomegaly

Maturation of the competence to evoke splenomegaly

Earlier work by Solomon (1960a) had shown that spleens taken from chicks of from 1 to 7 weeks of age (post-hatching) produced a 62 per cent, increase in host spleen-weight, but no hepatomegaly (Table 7). As the age of the donor chicken increased so did the extent of the hepatomegaly and splenomegaly of the embryonic hosts (Table 7). Spleens from male donors of from 9 to 16 weeks of age gave a significantly greater (P = 0·05) increase of spleen-weight above those of the 1–7-week age group. Although the 26–32-week-old male donor group did not produce significantly greater splenomegaly and hepatomegaly compared with that of the 9–16-week-old group, the 46–78-week-old donor group produced significantly greater (P = 0·05) splenomegaly than the 9–16-week-old group. No significant decreases in whole body-weight of the host embryos was observed in the experiments with male donors. The female donor spleen from 12–17-week- old chickens did not produce any hepatomegaly and no greater splenomegaly of the hosts than the 1–7-week-old male and female donor group. The 21–22- and the 52-week-old female donors both produced significantly greater (P = 0·05) hepatomegaly and splenomegaly than the 12–17 female donor group. Highly significant reductions of from 13 to 20 per cent, in the host body-weight were produced by female donors of from 12 to 52 weeks of age.

Table 7.

Maturation of the competence of juvenile chicken spleen to elicit splenomegaly

Maturation of the competence of juvenile chicken spleen to elicit splenomegaly
Maturation of the competence of juvenile chicken spleen to elicit splenomegaly

The ability of spleens from juvenile donors to produce splenomegaly in the host was re-examined with the sex of the donor and host determined. Results in Table 8 show that with male donors 6–17 weeks of age there was no sex difference in the increased spleen-weight of the hosts. However, when pieces of spleen from 6–20-week-old female donors were used as implants, the splenomegaly of the female hosts tended to be greater than that of the male hosts by as much as 14 mg. (Table 8). Although this tendency was not statistically significant within any individual experiment with female donor spleen, the total results from experiments in which female donors from 6 to 20 weeks were used showed a significantly increased mean spleen-weight (P = 0·05) and liver-weight (P = 0·01) of the female hosts above that of the male hosts. Solomon (1961) has since found that large implants (30 mg.) of macerated spleen from juvenile female donors produced an increase of spleen-weight of the female hosts which showed a highly significant (P = 0·01) difference from that of the other three sex combinations.

Table 8.

The splenic weight of chick embryos implanted with juvenile chicken spleen

The splenic weight of chick embryos implanted with juvenile chicken spleen
The splenic weight of chick embryos implanted with juvenile chicken spleen

The absence of sex differences in the reaction in male and female host spleens when small implants of adult cockerel or hen spleens were used as donor is shown in Table 9. Body-weights of experimental embryos were only 10 per cent, below those of the controls.

Table 9.

The splenic weights of chick embryos implanted with adult chicken spleen

The splenic weights of chick embryos implanted with adult chicken spleen
The splenic weights of chick embryos implanted with adult chicken spleen

The extent of the increase of spleenand liver-weight of a chick embryo acting as host to immunologically competent homologous cells is subject to a large number of biological variables. These include the number of competent donor cells injected, the genetic diversity between donor and host (Cock & Simonsen, 1958; Isacson, 1959; Mun, Kosin, & Sato, 1959), the extent of colonization of the host spleen by donor cells (Simonsen, 1957; Cock & Simonsen, 1958), and the age of the donor cells with regard to their immunological maturity. When cells are administered as implants there may be another variable due to the extent of the invasion of implant cells into the vascular system of the host.

Dantchakoff (1918) mentioned that she had found that homologous liver and bone-marrow as well as spleen produced splenomegaly of the host embryo. Willier (1924) found that thyroid, liver, thymus, and spleen produced splenomegaly. Ebert (1954) stated that of 11 tissues studied, only spleen, thymus, and liver were effective but that neither thymus and liver were as effective as spleen and that thymus was better than liver. However, in this work it has been shown for donors at various ages that small implants of liver, thymus, and bonemarrow are as effective at producing splenomegaly and hepatomegaly as splenic implants. Billingham & Silvers (1959) have found that adult chicken skin will also elicit splenomegaly. These results probably only mean that there are sufficient competent cells in these tissues capable of invading the hosts’ vascular systems and colonizing the hosts’ spleen. The concept of organ specificity due to protein templates (Weiss, 1947) does not appear to be tenable in this type of reaction as it is more probably due to a specific cell type such as the large lymphocyte (Terasaki, 1959) which can be found in several different tissues in the chicken.

Hepatomegaly, which does not always accompany splenomegaly in the initial stages of the graft versus host reaction, is presumably also produced by colonization of the liver by certain lymphoid cells from the implant. In this work hepatomegaly has usually accompanied splenomegaly; when homologous Spleen cells were injected intravenously into 15-day-old chick embryo hosts only the extent of the splenomegaly increased with cell dosage (Solomon, unpublished results). Hepatomegaly and splenomegaly are sometimes accompanied by reduction in whole body-weight which may be a ‘ranting’ effect. Such a reduction in whole body-weight has not been related to the extent of splenomegaly. Differentiation is not retarded in such runted embryos.

Biggs & Payne (1959) found by cytogenetic analysis of the enlarged chimeric chick spleens that about half of the cells in mitosis are of donor origin and that the other half belong to the host. While furnishing clear proof of colonization of intact dividing donor cells in the host spleen (cf. Ebert, 1959), the fact that mitotic division of the host spleen cells is possibly enhanced is of great interest. This reaction of the embryonic cells cannot be immunological as the embryo host is not yet competent. Biggs & Payne (1961) found that the splenomegaly syndrome lasted for 7 days after intravenous injection of adult cock spleen cells into 15-day-old chick embryos. It consisted of extensive proliferation of reticulum cell foci and a blast cell and granulocytopoietic response. Biggs & Payne suggested that the reticulum cell foci and some of the blast cells are of donor origin and that most of the blast cells and developing granulocytes may be of host origin.

As no splenomegaly occurs with non-competent (embryonic) homologous donor cells or with fully competent donor cells injected into an isologous host (Cock & Simonsen, 1958), the mitosis of the embryonic spleen is probably a secondary effect induced by the primary proliferation of colonies of neighbouring adult cells.

The cellular proliferation of competent donor cells on exposure to the tissue antigens of the host may be similar to the splenomegaly found in fowls treated with soluble antigens. Norton, Wolfe, & Crow (1950) obtained up to 75 per cent. increases in spleen-weight of fowls which had been injected with bovine serum albumin and some correlation with spleen size and precipitin titre was found. They found that splenomegaly was more rapid in birds older than 4 weeks posthatching. The onset and maturation of the ability to evoke splenomegaly in the graft versus host reaction shows, in chickens, some resemblance to the immunological maturation to other antigens (Buxton, 1954; Norton, Wolfe, & Crow, 1950; Wolfe & Dilkes, 1948).

The time of onset of the ability of donor cells to evoke splenomegaly in the host can be from 5 to 11 days post-hatching when the 8–18-day host system is used. This is in good agreement with the work of Simonsen (1957), who found the time of onset to be 11 days post-hatching when older embryos were injected with adult blood. In the 8–18-day host system, which is essentially the same as that used by Ebert (1951), it has been impossible to show such a well-defined time of onset except in one series of experiments on the same batch of chicks. More recent work (Solomon & Tucker, unpublished results) has indicated that this failure to obtain a well-defined time of onset in the 8–18-day host system may be due to the low extent of colonization of donor cells in the host spleen when embryos are implanted at 8 days of incubation. The onset of the ability of donor cells to evoke splenomegaly at 11 days post-hatching is in good agreement with the work on transplantation of skin grafts in the chick. Tolerance is most readily induced in embryos or newly hatched chicks, and the ‘null period’ between this phase and the age after which the chick will reject a skin graft occurs within the 2nd to the 7th day post-hatching (Cannon & Longmire, 1952; Billingham, Brent, & Medawar, 1956).

The student of development has difficulty in finding substances or functions which suddenly arise de novo during embryogenesis or later development. Some enzymes have been found to be at higher concentrations in embryonic tissues than in those of the adult (Solomon, 1957b, 1958) and attempts to induce synthesis of enzymes in embryos in vivo have so far been unsuccessful (e.g. Solomon, 1960b). The onset of the ability to evoke splenomegaly, while probably entirely cellular in nature, has the great virtue that it is entirely absent in embryonic life and is a clear example of a sudden acquisition of function during post-embryonal development.

Data in this work show that this ability increases with the age of the chicken, reaching a maximum at about 20 weeks post-hatching. These results are somewhat different to those of Ebert (1951), who claimed that the 6-week-old chicken spleen was mature in this respect although it and adult chicken spleen only produced a twofold increase in host spleen-weight. However, Ebert later (1954) obtained greater (fourfold) increases in host spleen-weight with adult cockerel donors, and this is in agreement with the present results. A similar maturation effect has been found in the homograft reaction in mice (Mariani, Martinez, Smith, & Good, 1959).

The small differences in the extent of splenomegaly between male and female hosts which have been found in this work have, as yet, no ready explanation. They are only apparent when young chick or juvenile female spleens are used as donor tissue and the reaction in the female host is greater than in the male hosts. The female-female donor-host combination in experiments using 8–21-day-old chick donors (Tables 5, 6) gave a mean spleen-weight of 24·6 mg., which was not significantly greater than that of the other three sex combinations when they were pooled (range of mean spleen-weights 16·9–21·2 mg.). However, in experiments with 6–20-week-old juvenile chicken donors (Table 8) the female-female donor-host combination gave a mean spleen-weight of 36·6 mg., and this was significantly greater (P = 0·02) than those of the other three sex combinations when they were pooled (range of mean spleen-weights 27·4–28·7 mg.). The finding that, under certain conditions, female hosts bear greater spleens than male hosts, may have a hormonal basis, and the enhancement of the splenomegaly syndrome by female hormone is being investigated.

Apparition et réalisation de la réaction anti-hôte du greffon chez le Poulet

  1. L’augmentation du poids brut de la rate de l’hôte après implantation de rate compétente de poulet jeune ou adulte correspond à une augmentation de son poids sec et de sa teneur en ARN, ADN et protéines.

  2. On n’a pas observé d’augmentation du poids de la rate de l’hôte quand on utilise comme greffon des cellules spléniques non compétentes d’embryon ou de poussin à l’éclosion.

  3. On a montré que l’apparition de la compétence immunologique en ce qui concerne cette réaction de transplantation se situe au 5e jour environ après l’éclosion, si on a implanté les rates dans des embryons au 8e jour de l’incubation, puis ôté la rate de l’hôte 10 jours plus tard.

  4. L’aptitude des cellules spléniques de poulet à provoquer l’hépatomégalie et la splénomégalie de l’embryon-hôte a augmenté avec l’âge, et a été maximale après l’âge de 21 semaines. Quelquefois aussi est survenue une diminution du poids corporel total des embryons-hôtes.

  5. Bien qu’on n’ait pas observé de différences selon le sexe dans le poids de la rate des hôtes quand on a utilisé comme greffons des rates de poussins mâles âgés de 8 à 15 jours, on a noté un accroissement significatif du poids du foie et de la rate des hôtes femelles par rapport à celui des mâles quand on a utilisé comme greffons des rates de poussins femelles âgés de 8 à 21 jours.

  6. Des cellules spléniques de poulets mâles de 6 à 17 semaines n’ont pas provoqué une splénomégalie beaucoup plus importante que ne l’ont fait celles de jeunes poussins, et il n’y avait pas de différences d’ordre sexuel entre les poids des rates des embryons-hôtes. Néanmoins, quand on a utilisé comme greffon une rate de femelle âgée de 6 à 20 semaines, on a observé une augmentation significative de l’hépatomégalie et de la splénomégalie des hôtes femelles, par rapport à celles des hôtes mâles.

  7. On n’a pas décelé de différences selon le sexe dans le poids des rates des embryons-hôtes quand on a utilisé comme greffon de petits implants de cellules spléniques d’adultes mâles ou femelles.

  8. Le thymus, le foie et la moelle osseuse de donneurs compétents sont presque aussi actifs que la rate pour produire la splénomégalie des embryonshôtes.

I am grateful to Miss J. A. Eckett and Mr. D. E. Palmer for their skilled technical assistance and to Professor A. Haddow, F.R.S., for his interest and encouragement in this work.

This investigation has been supported by grants to the Chester Beatty Research Institute (Institute of Cancer Research, Royal Cancer Hospital) from the Medical Research Council, the British Empire Cancer Campaign, the Jane Coffin Childs Memorial Fund for Medical Research, the Anna Fuller Fund, and the National Cancer Institute of the National Institutes of Health, United States Public Health Service.

Anreini
,
P.
,
Drasher
,
M. L.
, &
Mitchison
,
N. A.
(
1955
).
Studies on the immunological response to foreign tumour transplants in the mouse. III. Changes in weight and content of nucleic acids and protein of host lymphoid tissues
.
J. exp. Med
.
102
,
199
204
.
Biggs
,
P. M.
, &
Payne
,
L. N.
(
1959
).
Cytological identification of proliferating donor cells in chick embryos injected with adult chicken blood
.
Nature, Lond
.
184
,
1594
.
Biggs
,
P. M.
, &
Payne
,
L. N.
(
1961
).
Pathological changes following the inoculation of chick embryos with adult cells. 1. Spleen cells
.
Immunol
.
4
,
24
37
.
Billingham
,
R. E.
, &
Brent
,
L.
(
1959
).
Quantitative studies on tissue transplantation immunity. IV. Induction of tolerance in new bom mice and studies on the phenomenon of runt disease
.
Phil. Trans
.
243
,
439
77
.
Billingham
,
R. E.
,
Brent
,
L.
&
Medawar
,
P. B.
(
1956
).
Quantitative studies on tissue transplantation immunity. III. Actively acquired tolerance
.
Phil. Trans
.
239
,
357
412
.
Billingham
,
R. E.
, &
Silvers
,
W. K.
(
1959
).
Immunological competence of chicken skin
.
Immunol
.
82
,
448
57
.
Burton
,
K.
(
1956
).
Study of the conditions and mechanism of the diphenylamine reaction for the colorimetric estimation of deoxyribonucleic acid
.
Biochem. J
.
62
,
315
23
.
Buxton
,
A.
(
1954
).
Antibody production in avian embryos and young chicks
.
J. gen. Microbiol
.
10
,
398
410
.
Cannon
,
J. A.
, &
Longmire
,
W. P.
(
1952
).
Studies of successful skin homografts in the chicken
.
Ann. Surg
.
135
,
60
68
.
Ceriotti
,
G.
(
1955
).
Determination of nucleic acids in animal tissues
.
J. biol. Chem
.
214
,
519
70
.
Cock
,
A. G.
, &
Simonsen
,
M.
(
1958
).
Immunological attack on newborn chickens by injected adult cells
.
Immunology
,
2
,
103
10
.
Dantchakoff
,
V.
(
1918
).
Equivalence of different hematopoietic anlages (by method of stimulation of their stem cells). II. Grafts of adult spleen on the allantois and response of the allantoic tissues
.
Amer. J. Anat
.
24
,
127
73
.
Delanney
,
D. E.
(
1961
).
Unpublished
.
Duyff
,
J. W.
(
1929
).
The potencies and reactions of mesenchyme in fowls in connection with the problem of avian leucosis
.
Proc. K. Akad. Med. Wet
.
32
,
311
20
.
Ebert
,
J. D.
(
1951
).
Ontogénie change in the antigenic specificity of the chick spleen
.
Physiol. Zool
.
24
,
20
41
.
Ebert
,
J. D.
(
1954
).
Effects of chorioallantoic transplants of adult chicken tissues on homologous tissues of the host chick embryo
.
Proc. nat. Acad. Set. Wash
.
40
,
337
47
.
Ebert
,
J. D.
(
1959
).
The acquisition of biological specificity
.
In The Cell
, volume
i
, pp.
619
93
, ed.
J.
Brachet
&
A. E.
Mirsky
.
Isacson
,
P.
(
1959
).
Cellular transfer of antibody production from adult to embryo in domestic fowls
.
Yale J. Biol. Med
.
32
,
209
28
.
Mariani
,
T.
,
Martinez
,
C.
,
Smith
,
J. M.
, &
Good
,
R. A.
(
1959
).
Age of donor and host in sex histoincompatability to skin isografts
.
Proc. Soc. exp. Biol. N.Y
.
102
,
751
5
.
Mun
,
A. M.
,
Kosin
,
I. L.
, &
Sato
,
I.
(
1959
).
Enhancement of growth of chick host spleen following chorio-allantoic membrane grafts of homologous tissues
.
J. Embryol. exp. Morph
.
7
,
512
25
.
Norton
,
S.
,
Wolfe
,
H. R.
, &
Crow
,
J. F.
(
1950
).
Effect of injections of soluble antigen on the spleen size and antibody production in chickens
.
Anat. Rec
.
107
,
133
47
.
Simonsen
,
M.
(
1957
).
The impact on the developing embryo and newborn animal of adult homologous cells
.
Acta path, microbiol. scand
.
40
,
480
500
.
Solomon
,
J. B.
(
1957a
).
Nucleic acid content of early chick embryos and the hen’s egg
.
Biochim. biophys. Acta
,
24
,
584
91
.
Solomon
,
J. B.
(
1957b
).
Glutamic dehydrogenase in the developing chick embryo
.
Biochem. J
.
66
,
264
70
.
Solomon
,
J. B.
(
1958
).
Lactic and malic dehydrogenases in the developing chick embryo
.
Biochem. J
.
70
,
529
35
.
Solomon
,
J. B.
(
1960a
).
Onset of the ability of spleen cells to evoke the graft versus host reaction in chickens
.
Exp. Cell Res
.
20
,
223
6
.
Solomon
,
J. B.
(
1960b
).
Constitutive enzymes of the developing chick embryo: adenosine deaminase
.
Biochem. J
.
75
,
278
84
.
Solomon
,
J. B.
(
1961
).
Sex differences in the extent of splenomegaly associated with the graft against the host reaction in chicken
.
Sem. Hop. Paris, in press
.
Sutherland
,
E. W.
,
Cori
,
C. F.
,
Haynes
,
R.
, &
Olsen
,
N. S.
(
1949
).
Purification of the hyperglycaemic-glycogenolytic factor from insulin and from gastric mucosa
.
J. biol. Chem
.
180
,
825
37
.
Terasakt
,
P. I.
(
1959
).
Identification of the type of blood cell responsible for the graft versus host reaction in chicks
.
J. Embryol. exp. Morph
.
7
,
512
25
.
Weiss
,
P.
(
1947
).
The problem of specificity in growth and development
.
Yale J. Biol. Med
.
19
,
235
78
.
Willier
,
B. H.
(
1924
).
The endocrine glands and the development of the chick
.
Amer. J. Anat
.
33
,
67
103
.
Wolfe
,
H. R.
, &
Dilks
,
E.
(
1948
).
Precipitin production in chickens. III. Variation in the antibody response as correlated with the age of animal
.
J. Immunol
.
58
,
245
50
.