The effect of androgenic substances on the growth of the teat and mammary gland in the immature male guinea-pig

Abstract

Eggs or young larvae of an ichneumonid parasite, Nemeritis, injected into caterpillars of the tomato moth, Diataraxia, evoked a rapid reaction of the haemocytes, which led to the encapsulation of the parasite within 4 h. The further development of the capsule is described, and evidence is adduced that the encapsulated parasites were killed by asphyxiation. Encapsulation was blocked by injection of carbon particles, but only when the doses were so large that they affected the general health of the hosts; it was temporarily less intense in superparasitized hosts; and it appeared to be slightly depressed by cortisone. Attempts to induce tolerance in the host by various methods-by repeated parasitization, by inoculation with an homogenate of parasite larvae, by inoculation with the blood of a susceptible host and by embryonic inoculation of substances from an homogenate of parasite larvae-all failed to protect the parasite, which was encapsulated as thickly and rapidly as in untreated caterpillars. When the parasite was given prior experience of Diataraxia blood by two different methods it acquired no immunity. The haemocytic reaction was similarly evoked by other species of parasites, by dead parasites, by glass rods and pieces of nylon thread, by injured tissues of the caterpillar itself, and by organs transplanted from caterpillars of another species. Organs transplanted from other caterpillars of the same species attracted haemocytes only to injured surfaces. Haemocytic capsules formed in one caterpillar of Diataraxia and transplanted to another caterpillar of the same species were accepted as intraspecific implants and aroused no reaction; capsules formed in another species and transplanted to Diataraxia evoked a strong haemocytic reaction in the second host. It is concluded that surface properties of the parasite or implant determine whether or not it shall be encapsulated.