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Showing papers in "General and Comparative Endocrinology in 1968"


Journal ArticleDOI
TL;DR: The presence of specific hormones in excess of ontogenetically inappropriate times during development may compromise the capability of certain adaptive or survival value mechanisms at later stages of the life cycle, as well as provide for the later full expression of these adaptive mechanisms.

213 citations


Journal ArticleDOI
TL;DR: One of the prime effects of insulin is on the incorporation of glucose and amino acids into skeletal muscle, glycogen, and protein, and that these fish have a good homeostatic mechanism for the regulation of blood glucose concentration which appears to be relatively independent of insulin levels.

113 citations


Journal ArticleDOI
TL;DR: The cytological changes of the eta (“prolactin”) cells in the pituitary of Tilapia mossambica due to changes in environmental salinity have been described at both the light and electron-microscope levels, suggesting a high level of secretory activity.

103 citations


Journal ArticleDOI
TL;DR: Hydrocortisone increased liver and muscle glycogen, and blood glucose in hypophysectomized and intact eels, and may be important for gluconeogenesis in North American eels.

95 citations


Journal ArticleDOI
TL;DR: Sodium transport in the isolated intestine was increased by treatment with cortisol to a greater extent as in the case of water movement, and the significance of these results is discussed in relation to possible involvement of the pituitary-interrenal axis in seawater adaptation of the eel.

80 citations


Journal ArticleDOI
TL;DR: It is suggested that availability of thyroid hormone prior to birth and again after weaning age is reached, is not critical for development, possibly because other physiological factors operate to influence the rate of developmental processes.

77 citations


Journal ArticleDOI
TL;DR: Intraperitoneal injection of 0.03 mg per 10 gm body weight of a salmon pituitary gonadotropic preparation caused spermiation in all mature male hypophysectomized goldfish and human chorionic gonadotropin was also effective for spermiation.

72 citations


Journal ArticleDOI
TL;DR: A system of extracellular channels between the cells of the pars intermedia in continuity with dilatations of the Extracellular space, is described, and the findings are discussed in relation to the possible secretory function of the Pars inter media in mammals.

66 citations


Journal ArticleDOI
TL;DR: The data indicates that the secretion rate of cortisol is probably greater in the spawned than in the maturing fish, and the volume of distribution, biological half-life, and metabolic clearance rates of the dichloromethane-extractable radioactivity were calculated on the basis of a two-compartment model.

65 citations


Journal ArticleDOI
TL;DR: Porcine calcitonin injected, in doses of 10 mU and 50 mU, into two groups of eels with sham operations, caused a rapid decline in total Ca concentration and a rise in phosphate levels in the plasma.

63 citations


Journal ArticleDOI
TL;DR: Salmon pituitary gonadotropin purified by Sephadex G-100 was effective for spermatogenesis as well as spermiation in hypophysectomized male goldfish ( Carassius auratus ) as mentioned in this paper.

Journal ArticleDOI
TL;DR: Mammalian insulin was injected intraperitoneally into cyclostomes, cartilaginous fish, and marine and freshwater bony fish to cause a decrease of the sugar content in the blood, but the duration of hypoglycemia varied in different species.

Journal ArticleDOI
TL;DR: The effect of chronic low-level stress in elevating plasma cortisol is transitory and plasma “cortisol” levels in trout do not appear to be a useful indicator of the existence of chronic stressful conditions.

Journal ArticleDOI
TL;DR: There appeared also to be no sexual or age differences in the ability of the implants to secrete gonadotropin, at least for the hypophyses of fetuses between 11 and 28 weeks of embryogenesis.

Journal ArticleDOI
TL;DR: Pituitary glands of Xiphophorus lost more acidophilia and weight from the prolactin cells when cultured on dilute media than on concentrated media.

Journal ArticleDOI
TL;DR: Preliminary evidence suggests that increased lipolysis in the cockroach fat body in the presence of epinephrine may be mediated by cyclic 3′,5′-AMP.

Journal ArticleDOI
TL;DR: The data indicate that the thyroid-pituitary feedback is operating during the whole postnatal period and may be activated experimentally even before the physiological impact of this system becomes manifest.

Journal ArticleDOI
TL;DR: Two-day-old adrenals produce steroids of the same type as those of adult rats, and they are able to respond to exogenous ACTH, and following exogenous lysine vasopressin, the pituitary of 2- day-old rats increases ACTH production and release.

Journal ArticleDOI
TL;DR: The human fetal thyroid between the 65-80 mm crown-rump stage (73-80 gestational days) attains maturity in terms of relative weight, appearance of colloid containing central cavities, and ability to produce iodinated organic products, including thyroxine as mentioned in this paper.

Journal ArticleDOI
TL;DR: Female and feminized male gonads were similarly able to aromatize testosterone-6,7α-3H to produce tritiated estrone and estradiol-17β, but the yield was somewhat less than obtained from DHA-4-14C.

Journal ArticleDOI
TL;DR: It is concluded that the pineal complex of Mordacia is not involved in the pigmentary effector system, whereas the pineAl complex of Geotria plays an endocrine, as well as a photoreceptive role in the, control of melanophore behavior.

Journal ArticleDOI
TL;DR: The prolactins of vertebrates in the lungfish-tetrapod line are characterized by a high degree of PCS efficacy, and the pituitaries of fishes characteristically showno specific capacity to stimulate the pigeon crop.

Journal ArticleDOI
TL;DR: A hypothalamo-hypophyseal portal system and median eminence which by light and electron microscopy are comparable to those of tetrapods are demonstrated in the polypteriformid fishes Calamoichthys calabaricus and Polypterus Palmas.

Journal ArticleDOI
TL;DR: The fine structural changes in thyroid follicular epithelial cells of Xenopus laevis larvae throughout metamorphosis are described and the significance of the various organelles, especially with regard to the effects of thyrotropic stimulation, is discussed.

Journal ArticleDOI
TL;DR: It is concluded that prolactin interferes with the thyroidal iodide-trapping mechanism in tadpoles and also that some degree of peripheral action is involved, although the present experiments are not totally adequate to justify this latter point.

Journal ArticleDOI
TL;DR: It was concluded that 0.1, 0.15, and 0.2% thiouracil (TU) are equally effective in producing hypothyroid changes up to age 3 weeks, but PTU has a greater depressive effect on body weight because of its probably disagreeable taste and consequent effect upon food intake.

Journal ArticleDOI
TL;DR: Application of the assay to P. latipinna pituitary homogenates showed that the fish prolactin content of the pituitaries gland doubled during the 72 hours after transfer from dilute seawater to freshwater, and was still elevated after 4 weeks in freshwater.

Journal ArticleDOI
TL;DR: There was no synergism or additive effect with respect to total growth and the effects of prolactin on the liver were antagonized by the GH, and total lipid storage was the same under both hormone treatments but lipid distributions in the body differed, especially with regard to the liver.

Journal ArticleDOI
TL;DR: Ulastructural examination of the sinus glands of the crayfish following in vivo and in vitro electrical stimulation revels significantly fewer granules within the neurosecretory axon terminals than in similarly treated but unstimulated controls, suggesting granule depletion appears to be nonspecific with respect to the different terminal types.

Journal ArticleDOI
TL;DR: The morphology of the median neurosecretory cells of Periplaneta and “ordinary” invertebrate neurons is fundamentally identical.