Adult male rats (200-280 g) were exposed to pressures of 280-250 mm Hg. (25-28,000 ft) 6 hours daily for 14 to 18 days. The mean testicular, seminal vesicle and ventral prostate gland weights ± the Standard Error are shown in Table I. Body weight losses in the experimental animals averaged only 8.7%. Examination of sections of testes from low pressure-exposed rats (Group A) showed marked degeneration of the spermatogenic cells. Polychromasia and coalescence of cytoplasm, pyknosis of nuclei, and chromatolysis were observed in these reproductive elements. The tubular lumina were devoid of sperm. The interstitial tissue of the testis and epithelium of the seminal vesicle and prostate gland, however, appeared only slightly atrophied. Pituitary glands of the low pressure-subjected animals displayed increases in the numbers of basophiles. Some of these were enlarged and showed signs of degranulation. Others resembled the vacuolated cells occurring in pituitary glands after castration. The gonadotropic hormone contents of the pituitary glands from normal and low pressure-subjected rats were determined in 48 immature female rats employing the method of Reece and Weatherly. Three assay experiments were performed using pituitary glands from 3 different sets of animals. In each case, the gonadotropic hormone potency was found to be significantly greater in the glands obtained from the low pressure-exposed rats. The mean ovarian weight in the test animals injected with pituitaries from low pressure-exposed animals was 88.3 ± 6.5 mg as against a mean ovarian weight of 62.8 ± 3.9 mg in rats receiving normal pituitary glands. In another experiment, 8 rats were subjected to the same low pressure treatment but, in addition, were injected intrascrotally twice daily with 20 LIT. pregnancy urine hormone and 10 R.U. pregnant mare serum extract for 3 days preceding and during the entire period of exposure.
There appear to be ever increasing perplexities growing out of the multitudinous researches being perpetrated on the hypophyseal complex of the mammal. It has been suggested by some of the more valiant souls that relief may be found by a re-examination of the morphology of this structure in the lower vertebrates. Carlson, in his foreword to Van Dyke's monograph The Physiology and Pharmacology of the Pituitary Body, points out that the phylogeny of the pituitary-gland functions is a field of interest as yet inadequately explored. De Beer, in the preface to his book Comparative Anatomy, Histology and Development of the Pituitary Body, published eleven years ago (1926) makes the statement that since the pituitary is a complex organ, far more so than is generally supposed, any attempt to deal with it experimentally, either by preparing extracts or by excision, must be preceded by a knowledge of the anatomy of the...
EXPERIMENTAL WORK by several groups of investigators (Gordon, Goldsmith, andCharipper, 1944; Hughes and Astwood, 1944; Leblond, 1944) has established the fact that thiourea and thiouracil given in proper dosages and over a suitable period will increase the tolerance of rats to the anoxia produced by lowered barometric pressures. These drugsare members of a group of compounds known to interfere with the production of normal thyroid hormone (Mackenzie and Mackenzie, 1943; Astwood, 1943; Astwood, Sullivan, Bissell andTyslowitz, 1943; Keston, Goldsmith, Gordon and Charipper, 1944; Franklin, Lerner and Chaikoff, 1944; Dempsey, 1944) and in this way serving to lower the basal metabolic rate (Mackenzie and Mackenzie, 1943; Astwood, Sullivan, Bissell and Tyslowitz, 1943). It has been reported previously that thyroidectomized rats withstand exposures to anoxia induced byreduced atmospheric pressures better than do normal animals (Streuli, 1918; Duran, 1920; Barach, Eckman and Molomut, 1943). Administration of thyroid or anterior pituitary substanceincreases the sensitivity of animals to oxygen deficiency
1. The RBC and hemoglobin content of normal rats show higher values than those of normal females. 2. Following castration, the RBC and hemoglobin contents of the males drop, while those in the females rise. 3. Injections of estradiol into castrated females, and testosterone into castrated males produce, respectively, a drop and rise in RBC and hemoglobin. 4. Bone marrow studies indicate that androgens stimulate and estrogens inhibit erythro-cytopoiesis. 5. Additional support is thus given to the sex hormone explanation of the normal sex difference in RBC reported for many species of animals.
Summary1. Immature splenectomized rats injected with pregnancy urine extract for 20 days produce a smaller quantity of inhibitory substance than normal injected controls. 2. “Blockage” experiments with trypan blue indicate that the production of antagonistic principle is not peculiar to the spleen but is possessed by the reticuloendothelial system as a whole.
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