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In confirmation of Shirai's observation, we find that transplantable mouse tumors grow actively when inoculated into the brains of rats, guinea pigs, and pigeons, whereas subcutaneous or intramuscular grafts in the same animals fail. This growth of foreign tissue in the brain, however, takes place only when the grafted material lies entirely in the brain tissue; if it comes in contact with the ventricle a cellular reaction takes place with resultant destruction of the graft. The growth of foreign tissue in the brain may be completely inhibited by simultaneous inoculations of a small bit of autologous but not by a bit of homologous spleen tissue. Mice highly immune to subcutaneous transplants of mouse cancer show no resistance to such tumors when the inoculation is made into the brain. Although the brain is without obvious power of resistance to implants of transplantable heteroplastic mouse tumors, yet grafts of spontaneous tumors fail to grow there even, as a rule, when tumor implanted and animal host are of the same species.

No abstract

Inoculation of the Jensen rat sarcoma into the developing chick embryo gives a rapidly growing tumor at the site of inoculation, whether in the membranes or in the body of the chick itself. These tumors by transfer from embryo to embryo can be kept going for as long as forty-six days, and perhaps indefinitely in the foreign species. The rat cells show no morphological change even after a very long dependence. Their biological characters are also retained, as is shown by the fact that the cells when replanted in the rat, after a prolonged sojourn in the chick, will produce a rapidly growing sarcoma of the Jensen type. These rat tissues grown for long periods in the chick show no adaptation to the new species, being destroyed even more rapidly when placed in the adult chicken than cells taken directly from the rat. Morphologically the cells retain a close resemblance to those in the original tumor. Other tissues grown in chick embryo are various embryonic cells from the chicken, mouse, and rat, the Ehrlich sarcoma and chondroma of the mouse, a mammary carcinoma of the mouse, the Flexner-Jobling adenocarcinoma of the rat, and a human sarcoma.

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The direct inoculation of a sarcoma of the fowl into the developing chick embryo or its membranes has yielded growths in many cases. The best results have been obtained with grafts of the living tumor tissue, but, as in the adult, growths can be engendered with dried tissue or with the Berkefeld filtrate of a tumor extract. When living tumor tissue is used, an actual transplantation occurs. The neoplasms developing are spindle-celled sarcomata, remarkably uniform in structure, and similar to those in the adult fowl, except that in the embryo the neoplastic cells are often extremely long and slender, and the structure of the growth is very loose. The membranes adapt themselves in a remarkable way to the support of the tumors. In them, the growth is seldom invasive; and while regional metastases are occasionally seen, none occur by the bloodstream, despite the predilection of the growth for this path of distribution in adult hosts. In the more resistant structures of the embryo itself, an invasive extension of the sarcoma occurs. Growths originally in the yolk-sac outside the chick may be carried into the latter during the course of development. Secondary growths in the viscera may cause the death of the host some weeks after hatching. In order to produce tumors in the embryo, the sarcoma cells or the agent engendering the growth must be brought into a direct association with the mesodermal tissues. This necessity is responsible for interesting differences in the location of the growths in the various membranes. The sarcoma will grow in the membranes of pigeon or duck embryos, whereas in adults of these species it will not do so; and in chicken embryos of different varieties, it grows uniformly well, a finding not obtained in adults. In embryo hosts of all the sorts mentioned, there is a total absence of the cellular reaction which in adults indicates resistance to the tumor's development. Relatively speaking, the embryo seems much more favorable than the adult as a host for the sarcoma.

Knowledge of basic gamete biology is critical to better protect and propagate endangered amphibian species and also to develop reproductive technologies combined with germplasm cryopreservation. The objectives of the study were to test different hormonal stimulations and then characterize the quantity and quality of Panamanian golden frog (Atelopus zeteki) spermatozoa. Following intraperitoneal injection of the gonadotropin-releasing hormone agonist (des-Gly, D-Ala, Pro-NHEt-GnRH 1, 2 or 4 μg/g of body weight), human chorionic gonadotropin (hCG; 5 or 10 IU/gbw), or Amphiplex™ (0.4 μg/gbw GnRH-A + 10 μg/gbw metoclopramide hydrochloride), spermic urine samples from 29 males were collected at different time points (from 0.5 to 24 h post-injection) to analyze the concentration, motility, and morphology of the spermatozoa. Peak of sperm concentration was observed at 3.5 h post injection for all hormonal treatments. Amphiplex™ led to the highest sperm concentrations (4.45 ± 0.07 × 10 cells/mL) followed by 4 μg/gbw GnRH-A (2.65 ± 0.21 × 10 cells/mL). Other stimulation protocols and doses induced sperm production, but at lower levels (ranging from 1.34 to 1.70 × 10 cells/mL). More than 60% of spermatozoa were motile following all treatments but the highest motility (>90%) was obtained from the 10 IU/gbw hCG treatment. Spermic urine samples obtained with all hormone treatments had higher pH (ranging from 7.1 to 7.8) than the urine alone (6.7-6.8). Spermatozoa were filiform and elongated with an apical acrosome, a mitochondrial sheath, a small midpiece and a long tail with an undulating membrane. More than 80% of cells were morphologically normal and 50-70% had intact DNA. These sperm characteristics were not influenced by hormonal treatments. This first comprehensive characterization of sperm samples following optimized hormonal stimulations in A. zeteki lays the foundation for more fundamental studies, reproductive technologies, and future preservation strategies.

In the course of experiments on the factors of resistance to heteroplastic tissue grafts in the chick embryo, observations were made on the effects of certain organ grafts on the embryo itself.' The working out of the finer histological details of this process has been taken up, at my suggestion, by Dr. Vera Danchakoff. This brief note on the original observations is published now for completeness and record.Experiments.-On the 7th day of incubation openings were made in the shells of hens' eggs containing embryos, and small amounts of finely divided adult organs were deposited on the outer membrane (allantois and chorion). After this procedure the eggs were closed and sealed with paraffin and then returned to the incubator. On the 17th or 18th day of incubation the eggs were opened for examination. This constituted a control for the experiments on heteroplastic grafting, where, in the main experiment, grafts of heterologous tissues were introduced with an addition of grafts of homologous adult organs. 2 As there were a comparatively small number of eggs with the organ grafts alone in each experiment and as the technique throughout the series was the same, the results as a whole will be considered rather than the individual experiments. The adult chicken tissues used for the experiments were spleen, liver, kidney, bone marrow, pancreas, bone, and muscle. With the exception of pancreas, which caused wide-spread digestion of the embryonic tissues, all the tissues survived the grafting. As only spleen, liver, 'Murphy, Jas. B.,