FISHERY BULLETIN: VOL, 71, NO. 1 



The comparison of techniques for the demon- 

 stration of TSH activity of the pituitary homoge- 

 nates on the thyroid clearly indicates the inad- 

 equacy of histological methods. In spite of a 

 highly significant increase in the release of thy- 

 roxine there was no change observed in the 

 follicular epithelium nor in measurements on the 

 colloid weight per unit area. This method is 

 capable of detecting the response of teleost thy- 

 roid follicles to a 24-hr incubation with mam- 

 malian TSH (Bromage and Sage, 1968). 



While the results of incubations of thyroid 

 with pituitary homogenates indicate TSH ac- 

 tivity is present in the pituitary, they do not 

 indicate whether it is of functional significance. 

 An obvious followup to these experiments would 

 be the removal of the ventral lobe and the mea- 

 surement of blood thyroxine levels. However, 

 removal of the ventral lobe in this species has 

 not so far been possible due to the close associ- 

 ation of this region with the carotid anastomosis. 



Furthermore, the analysis of thyroxine in 

 elasmobranch blood by the present methods is 

 difficult due to unknown factors in the blood 

 which interfere with thyroxine analysis. From 

 this study we conclude that TSH activity is pre- 

 sent in the elasmobranch pituitary and that most 

 of this activity is in the ventral lobe. However 

 the functional significance of this activity re- 

 mains to be determined. 



ACKNOWLEDGMENTS 



We are indebted to Mr. J. Thompson and his 

 staff at the Marine Science Institute, especially 

 Boat Captains E. Wingfield and J. Shanklin for 

 help in collecting Atlantic stingrays. We also 

 thank Dr. V. de Vlaming and L. C. Sage for 

 their comments on the manuscript. Supported 

 by NSF grant GB 22995. 



LITERATURE CITED 



Bakke, J. L., M. L. Heideman, N. L. Lawrence, and 

 C. Wiberg. 



1957. Bioassay of thyrotropic hormone by weight 

 response of bovine thyroid slices. Endocrinology 

 61:352-367. 

 Bromage, N. R., and M. Sage. 



1968. The activity of the thyroid gland of Poecilia 



during the gestation cycle. J. Endocrinol. 41 : 303- 

 311. 



Dent, J. N., and J. M. Dodd. 



1961. Some effects of mammalian thyroid stim- 

 ulating hormone, elasmobranch pituitary gland 

 extracts and temperature on thyroidal activity 

 in newly hatched dogfish (Scyliorhinus caniculus) . 

 J. Endocrinol. 22:395-402. 



Dodd, J. M., P. J. Evennett, and C. K. Goddard. 



1960. Reproductive endocrinology in cyclostomes 

 and elasmobranchs. Symp. Zool. Soc. Lond. 1:77- 

 103. 



Dodd, J. M., K. M. Ferguson, M. H. I. Dodd, and 

 R. B. Hunter. 



1963. The comparative biology of thyrotropin se- 

 cretion. In S. C. Werner (editor). Thyrotropin, 

 p. 3-38. Charles Thomas, Springfield. 



Fontaine, Y. A. 



1969. Studies on the heterothyrotropic activity of 

 preparations of mammalian gonadotropins of tel- 

 eost fish. Gen. Comp. Endocrinol. Suppl. 2:417- 

 424. 



Galton, V. A., AND R. Pitt-Rivers. 



1959. A quantitative method for the separation 

 of thyroid hormones and related compounds from 

 serum and tissues with an anion-exchange resin. 

 Biochem. J. 72:310-313. 



GORBMAN, A. 



1969. Thyroid function and its control in fishes. 

 In W. S. Hoar and D. J. Randall (editors). Fish 

 physiology. Vol. 2, p. 241-274. Academic Press, 

 N.Y. 

 NicoLL, C. S., AND H. A. Bern. 



1964. Prolactin and the pituitary glands of fishes. 

 Gen. Comp. Endocrinol. 4:457-471. 



Olivereau, M. 



1954. Hypophyse et glande thyroide chez les pois- 

 sons. Etude histophysiologique de quelques cor- 

 relations endocriniennes en particulier chez Sal- 

 mo salar L. Ann. Inst. Oceanogr. Monaco 29 : 

 95-296. 



PiLEGGI, V. J., AND G. KeSSLER. 



1968. Determination of organic iodine compounds 

 in serum. IV. A new nonincineration technic for 

 serum thyroxine. Clin. Chem. 14:339-347. 



PiLEGGi, V. J., D. N. Lee, 0. J. Golub, and R. J. Henry. 



1961. Determination of iodine compounds in serum. 

 I. Serum thyroxine in the presence of some iodine 

 contaminants. J. Clin. Endocrinol. Metab. 21 : 

 1272-1279. 



Pitt-Rivers, R., and J. R. Tata. 



1959. The thyroid hormones. Pergamon Press, 

 Lond., 247 p. 

 Sage, M. 



1968a. Assay of mammalian and fish TSH. J. En- 

 docrinol. 41:xv. 

 1968b. Responses to osmotic stimuli of Xiphophorus 

 prolactin cells in organ culture. Gen. Comp. 

 Endocrinol. 10:70-74. 





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