Summary
There were no consistent significant differences between the concentrations of luteinizing hormone (LH) and adrenocorticotrophin (ACTH) in the rostral compared with the caudal zone of the echidna pars distalis. This suggests that LH is secreted by cells containing S-type granules (probably corresponding to secretory vesicles 200–300 nm diameter) which are distributed throughout the gland. Some of the cells containing vesicles 100–200 nm diameter, seen in small numbers in both zones of the gland, may be responsible for the secretion of ACTH. The concentration of pituitary LH is in the range of that found in eutherian mammals, but the concentration of ACTH is lower than that reported for other vertebrates, and this may be linked causally with the remarkably low rate of corticosteroid secretion in the echidna. The absence of significantly increased levels of pituitary LH and ACTH in a chronically orchidectomized and adrenalectomized animal adds to other evidence which suggests that mechanisms involving a negative feedback of steroid hormones on the hypothalamo-hypophysial axis may not be fully developed in the echidna.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Adams, C. W. M., Swettenham, K. V.: The histochemical identification of two types of basophil cell in the normal human adenohypophysis. J. Path. Bact. 75, 95–103 (1957)
Augee, M., Fink, G., Smith, G. C.: Morphological and experimental studies on the pars distalis of the echidna (Tachyglossus aculeatus). J. Anat. (Lond.) 108, 208 (1971)
Augee, M. L., McDonald, I. R.: Role of the adrenal cortex in the adaptation of the monotreme Tachyglossus aculeatus to low environmental temperature. J. Endocr. 58, 513–523 (1973)
Bliss, C. I.: The statistics of bioassay with special reference to the vitamins. New York: Academic Press 1952
Brown-Grant, K., El Kabir, D. J., Fink, G.:The effect of mating on pituitary luteinizing hormone and thyrotrophic hormone content in the female rabbit. J. Endocr. 41, 91–94 (1968)
Farquhar, M. G.: Processing of secretory products by cells of the anterior pituitary gland. In: Subcellular organization and function in endocrine tissues. Eds. H. Heller and K. Lederis, p. 79–122. Cambridge: The University Press 1970
Griffiths, M.: Echidnas. Oxford: Pergamon 1968
Hanström, B., Wingstrand, K. G.: Comparative anatomy and histology of the pituitary in the egg-laying mammals, the monotremata. Lunds Univ. Arssk. N. F. Adv. 2, 47, Nr. 6; Kungl., Fysiog., Sallsk., Handl. N. F. 62, Nr. 6, 1–39 (1951)
Kurosumi, K., Kobayashi, Y.: Corticotrophs in the anterior pituitary glands of normal and adrenalectomized rats as revealed by electron microscopy. Endocrinology 78, 745–758 (1966)
Li, C. H.: Hormones of the anterior pituitary gland, Part 1. Growth and adrenocorticotropic hormones. Advanc. Protein. Chem. 11, 101–190 (1956)
Mattingly, D.: A simple fluorimetric method of the estimation of free 11-hydroxycorticoids in human plasma. J. clin. Path. 15, 374–379 (1962)
McDonald, I. R., Augee, M. L.: Effects of bilateral adrenalectomy in the monotreme Tachyglossus aculeatus. Comp. Biochem. Physiol. 27, 669–678 (1968)
McShan, W. H.: Secretory granules from anterior pituitary glands. In: Subcellular organization and function in endocrine tissues. Eds. H. Heller and K. Lederis, p. 161–183. Cambridge: The University Press 1970
Naftolin, F., Brown-Grant, K., Corker, C. S.: Plasma and pituitary luteinizing hormone and peripheral plasma oestradiol concentrations in the normal oestrous cycle of the rat and after experimental manipulation of the cycle. J. Endocr. 53, 17–30 (1972)
Ortman, R., Griesbach, W. E.: The cytology of the pars distalis of the wallaby pituitary. Aust. J. exp. Biol. Med. 36, 609–618 (1958)
Parlow, A. F.: Bio-assay of pituitary luteinizing hormone by depletion of ovarian ascorbic acid. In: Human pituitary gonadotrophins. Ed. A. Albert, p. 300–310. Illinois: Thomas 1961
Pearse, A. G. E.: Histochemistry theoretical and applied, 2nd ed. London: Churchill 1961
Purves, H. D.: Cytology of the adenohypophysis. In: The pituitary gland. Eds. G. W. Harris and B. T. Donovan, vol. 1, p. 147–232. London: Butterworths 1966
Purves, H. D., Sirett, N. E.: A study of the hormone contents of the rostral and caudal zones of the pars anterior of the wallaby pituitary. Aust. J. exp. Biol. Med. 87, 271–277 (1959)
Semon, R.: Die Embryonalhüllen der Monotremen und Marsupialier. Denk. Med. Naturw. Ges. Jena 5, 17–58 (1894a)
Semon, R.: Zur Entwickelungsgeschichte der Monotremen. Denk. Med. Naturw. Ges. Jena 5, 59–74 (1894b)
Siperstein, E. R., Allison, V. F.: Fine structure of the cells responsible for secretion of adrenocorticotrophin in the adrenalectomized rat. Endocrinology 76, 70–79 (1965)
Smith, G. C.: Experimental and comparative studies on the median eminence of the rat and the echidna. Thesis for the degree M. D. Monash University (1972)
Weiss, M., McDonald, I. R.: Corticosteroid secretion in the monotreme Tachyglossus aculeatus. J. Endocr. 33, 203–210 (1965)
Author information
Authors and Affiliations
Additional information
We thank Dr. I. R. MacDonald, Department of Physiology, Monash University, for providing the animals, and are grateful to Mr. A. Kreibich and Mr. G. Rolls for their expert assistance, the National Institute of Arthritis and Metabolic Diseases, Bethesda for their gift of luteinizing hormone, and the National Health and Medical Research Council for financial support.
Rights and permissions
About this article
Cite this article
Fink, G., Smith, G.C. & Augee, M.L. Histochemical, ultrastructural and hormonal studies on the pars distalis of the echidna (Tachyglossus aculeatus). Cell Tissue Res. 159, 531–540 (1975). https://doi.org/10.1007/BF00221708
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00221708