The distribution of myoepithelium and smooth muscle in the lactating mammary gland of the goat has been examined by a new technique of silver impregnation which is applicable to sections up to 100μ in thickness. Myoepithelium covers the stromal surface of the epithelium of the alveoli, ducts and cisterns of the entire gland, and is thus much more abundant than is generally realized. Smooth muscle forms scattered inter-lobular bundles closely associated with the blood vessels. The theory that myoepithelial contraction is the principal factor concerned with 'let-down' and the ejection of milk is examined; other factors such as inter-lobular smooth muscle contraction, vascular changes, and elastic recoil of the stroma appear to play minor roles, if any, in this phenomenon. Hitherto, it has been assumed that myoepithelial cells are contractile because they bear structural resemblances to smooth muscle fibres. With the new technique structural changes have been found in the myoepithelium of contracted as compared with distended alveoli and ducts. These changes, together with the general orientation of myoepithelial cells, and the precise relationship between these cells and the folds in the secretory epithelium from contracted glands, are consistent with the assumption that myoepithelium is the contractile tissue in the mamma which responds to a neurohormonal mechanism involving oxytocin.
Similar content being viewed by others
References
Arnstein, C. 1895 Anat. Anz. 10, 410.
Babkin, B. P. 1944 Secretory mechanism of the digestive glands, p. 676. New York: Hoeber.
Benda, C. 1894 Derm. Z. 1, 94.
Bertkau, F. 1907 Anat. Anz. 30, 161.
Biggs, R. 1947 J. Path. Bact. 59, 437.
Boeke, J. 1934 Z. mikr.-anat. Forsch. 35, 551.
Buley, H. M. 1938 Arch. Derm. Syph., N.Y., 38, 340.
Dempsey, E. W., Bunting, H. & Wislocki, G. B. 1947 Amer. J. Anat. 81, 309.
Ely, F. & Petersen, W. E. 1939 Amer. Soc. An. Prod. 32nd Ann. Meet. 80.
Ely, F. & Petersen, W. E. 1941 J. Dairy Sci. 24, 211.
Folley, S. J. 1947 Brit. Med. Bull. 5, 142.
Folley, S. J. & Greenbaum, A. L. 1947 Biochem. J. 41, 261.
Gaines, W. L. 1915 Amer. J. Physiol. 38, 285.
Hammond, J. 1936 Vet. Rec. 16, (N.S.), 519.
Hoerr, N. L. 1936 Anat. Rec. 66, 149.
Kuzma, J. F. 1943 Amer. J. Path. 19, 473.
Lenfers, P. 1907 Z. Fleisch- u. Milchhyg. 17, 340, 383, 424.
McClung, C. E. 1937 Handbook of microscopical technique, 461. Oxford University Press.
Petersen, W. E. 1942 Proc. Soc. exp. Biol., N.Y., 50, 298.
Petersen, W. E. & Ludwick, T. M. 1942 Fed. Proc. 1, 66.
Peyron, A. Corsy, F. & Surmont, J. 1926 Bull. Ass. franc. Cancer, 15, 21.
Retterer, E. & Lelievre, A. 1911 J. Anat., Paris, 47, 8.
Schäfer, E. A. 1915 Quart. J. exp. Physiol. 8, 379.
Sheldon, W. H. 1941 Arch. Path Lab. Med. 31, 326.
Sheldon, W. H. 1943 Arch. Path. Lab. Med. 35, 1.
Swanson, E. W. & Turner, C. W. 1941 J. Dairy Sci. 24, 635.
Takahara, K. 1934 Quoted from The physiology of human perspiration, Y. Kuno, 1934, p. 28. London: Churchill.
Tgetgel, B. 1926 Schweiz. Arch. Tierheilk. 68, 335, 369.
Turner, C. W. 1931 Res. Bull. Mo. agric. exp. Sta. No. 160.
Turner, C. W. 1939 The comparative anatomy of the mammary glands (with special reference to the udder of cattle). Columbia, U.S.A.: University Missouri Co-op. Store.
Turner, C. W. & Gomez, E. T. 1936 Res. Bull. Mlo. agric. exp. Sta. No. 240.
Weber, A. 1944 Bull. Histol. Tech. micr. 21, 45.
Yen, T. J. 1924 Quoted from The physiology of human perspiration, Y. Kuno, 1934, p. 27. London: Churchill.
Author information
Authors and Affiliations
Additional information
Communicated by J. Z. Young, F.R.S.
Rights and permissions
About this article
Cite this article
Richardson, K.C. Contractile tissues in the mammary gland, with special reference to myoepithelium in the goat. J Mammary Gland Biol Neoplasia 14, 223–242 (2009). https://doi.org/10.1007/s10911-009-9135-7
Received:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10911-009-9135-7