Summary In the present investigations, referring to conventional milking machines and conventional milking technique, teat ends were transversally compressed for a short moment by means of a cutimeter before, during and after milking (main series), or before and after milking (additional series). The thickness of the teat ends between the jaw plates of the instrument decreased during the high flowrate phase, increased during the low flowrate and overmilking phases, and started decreasing as soon as milking was finished. The decreased values in the beginning of the milking process reflect the thinning of the teat wall following the vacuum‐induced teat elongation that occurs when the teatcups are attached. The subsequent increased values are due to active, i.e., functionally significant hyperaemia in the teat wall, especially in the specific teat venous system, and locally elevated vascular pressure. Both the thinning and the thickening seem to occur within physiologically tolerable limits. The diagnosis, proposed in the literature, of teat congestion (passive hyperaemia) and/or oedema involving risks of impaired teat and udder health has no support in our investigations.

The distribution pattern of myoepithelial cells in the bovine mammary gland was investigated by an immunohistochemical technique, using monoclonal antibodies against cytokeratins 5, 6 and 18 and cytokeratins 8 and 14 and against α-smooth-muscle actin filaments. Myoepithelial cells were shown to be present as a continuous basal cell layer in the intralobular ducts, as discontinuous cell rows in the basal cell layer of the interlobular ducts, and as single cells dispersed in the basal cell layer of the quarter cisterns, while they were apparently absent in the teat cisterns. Unlike the case with myoepithelial cells of the human breast, anti-cytokeratin 14 was less specific as a marker of bovine myoepithelial cells than was anti-α-smooth-muscle actin.

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