Host―parasitoid metapopulations : the consequences of parasitoid aggregation on spatial dynamics and searching efficiency

Antibodies prepared in a number of species of mammals, when injected into the uterine lumen of the rabbit, penetrate the yolk-sac splanchnopleur and are found in the foetal circulation. The concentrations achieved in the foetal serum vary according to the species of origin of the immune serum. The present work was undertaken further to investigate the mechanism of this selection, and to determine what part might be played by degradation of the injected protein. Normal bovine, and immune rabbit $\gamma $-globulins were trace labelled with $^{131}\text{I}$ and injected into the uterine lumen of rabbits 24 days pregnant. It was found that rabbit agglutinin, and rabbit and bovine iodoglobulin, were present in the serum of foetuses thus exposed. The concentrations of both rabbit agglutinin and rabbit iodoglobulin in the foetal circulation, relative to those injected, were lower than is the case when natural antitoxin is used. The relative concentration of rabbit to bovine iodoglobulin in the foetal circulation is not greatly different from that of rabbit to bovine antitoxin using natural serum. Injections were made into one horn of the bicornuate uterus; high concentrations of isotope were discovered in the non-protein fraction of the serum of foetuses in the control uteri. The total isotope content of foetuses in the injected uteri was always greater than that of those in the control uteri; this excess is considered to be due to direct uptake from the uterine lumen. It is in part accounted for as circulating iodoglobulin; the remainder, amounting to approximately one-twentieth of the dose injected, is of equal magnitude whether bovine or rabbit protein has been injected.