562 



Ontogeny of Immunological Properties 



at various developmental stages, using anti- 

 sera against the euglobulin, pseudoglobulin 

 and albumin fractions, as well as against 

 whole serum. The antisera against the serum 

 fractions cross-reacted with the respective 

 fractions and with egg yolk. After absorption 

 with the heterologous fractions the antisera 

 still reacted with the homologous fractions 

 and with egg yolk. After additional absorp- 

 tion with egg yolk the euglobvilin antiserum 

 still reacted with the homologous antigen but 

 the pseudoglobulin and albumin antisera 

 failed to do so. Apparently the latter two 

 fractions possess no antigens that are not 



of incubation, and more slowly subsequently. 

 These workers suggest that the vitelloid 

 constituent may be a pseudoglobulin pos- 

 sibly identical with livetin, whereas the 

 non-vitelloid constituent may be represented 

 by servim albumin. However, this does not 

 seem to be quite consistent with the pre- 

 viously reported (Schechtman, '47) results 

 showing that when antisera against pseudo- 

 globvilin and antisera against albumin are 

 absorbed with yolk they no longer react with 

 the homologous antigen (see above). 



In another set of experiments, Schechtman 

 ('48) prepared antisera against a saline ex- 



Table 25. Reactions (Ring Tests) of Rabbit Anti-19-day-Chick-Enibryo-Brain 

 Sera with Extracts of Blood and Organs of 19 -day Embryos and of 

 Early Embryos [from Schechtman, '48) 



also present in the heterologous fractions and 

 in yolk. 



The tests with embryo extracts were made 

 with anti-whole servim and with anti-euglob- 

 ulin (absorbed with pseudoglobulin and 

 albumin). Both of these antisera reacted with 

 extracts of embryos (free of visible yolk), 

 from the primitive streak stage to the 15- to 

 17-somite stage. However, after absorption 

 with yolk the antisera no longer reacted with 

 these extracts, but still reacted with adult 

 serum and with the blood and also the per- 

 fused (liver and brain) or washed (heart and 

 muscle) organs of the 19- 20-day embryo. 

 Thus, of the antigens detectable by these anti- 

 sera, the extracts of the early embryos con- 

 tain only those that are common to yolk, 

 and that may be termed "yolk-like" or "vitel- 

 loid." Although blood is present in the 7- to 

 8-somite and 15- to 17-somite stages that were 

 tested, the "non-vitelloid" antigens of adult 

 serum were not detectable. 



Further detailed tests by Nace and 

 Schechtman ('48), with yolk-absorbed an- 

 tisera vs. adult serum, showed that "non- 

 vitelloid" antigens are first detectable in the 

 blood of 5-day embryos. These increase rap- 

 idly in relative amount up to the ninth day 



tract of perfused brain of chicks of 19 to 

 20 days of incubation. These antisera cross- 

 reacted with extracts of liver, heart, muscle 

 and blood of chicks of the same stage, with 

 yolk and with extracts of yolk-free embryos 

 at the primitive streak, early neurula and 

 4- to 5-somite stages. Upon absorption with 

 blood the antisera no longer reacted with 

 yolk but still reacted with the various organ 

 and early embryo extracts (see Table 25). 

 It appears, then, that antigens of the brain 

 extract that are not present in blood or yolk 

 are present in the early embryos and the 

 other organs tested. These antigens are evi- 

 dently not specific for brain, since absorption 

 of the anti-brain sera with either liver or 

 heart removes reactivity for brain and for 

 the early embryos. Ebert ('50) partly con- 

 firms these results, but Burke et al. (see 

 above) obtained a brain-specific antiserum 

 after absorption with heterologous organs 

 and found that the absorbed antiserum re- 

 acted with extracts of late stages but not 

 of early stages. The basis for this discrep- 

 ancy is not clear. 



In the sea urchin Paracentrotus, Perlmann 

 and Gustafson ('48) find common antigens 

 to be present at stages from the unfertilized 



