Responses of the salivary glands to distension of the oesophagus and rumen

The rate of flow and composition of various salivary secretions in sheep and calves

“…The viscosity of the saliva increased with the rate of flow. The composition of submaxillary saliva collected from anaesthetized sheep and calves during the experiments reported by Kay & Phillipson (1959) is shown in Table 7. In general the composition of the sheep samples was intermediate between the zero flow and the most slowly secreted samples shown in Text- fig.…”

“…In some experiments the remaining salivary secretions, which will be called the residual saliva, were collected as they dripped from the mouth and nose. Many of these samples were collected during the experiments reported by Kay & Phillipson (1959). Saliva was stored under liquid paraffin at 10 C until analysed.…”

“…The parotid glands secrete rapidly and continuously, but the submaxillary glands secrete little except during feeding periods (Colin, 1886;Scheunert & Trautmann, 1921). In addition, considerable quantities of saliva are secreted continuously by the small glands of the mouth (Scheunert & Krzywanek, 1929;Phillipson & Reid, 1958;Kay & Phillipson, 1959) but the glands which contribute to this secretion have not been examined in detail.…”

The development of parotid salivary secretion in young goats

“…The ability to secrete is especially poorly developed during the first 5 weeks of life, when there is almost no continuous secretion and the response to stimulation is only about one third of that of an equal weight of adult parotid tissue. In young calves also the parotid glands secrete slowly if at all (Epaneshnikov, 1935;Kay, 1958b) and it is possible that they develop less rapidly than in the goat for Kay & Phillipson (1959) found that the maximum rate of secretion by reflexly stimulated parotid glands (ml./g. hr) is considerably less in calves from 4 to 8 months old than in adult sheep.…”

“…The first was collected without the application of any stimulus to secretion, and the second while the thoracic oesophagus was distended with either a rubber tube or a balloon introduced through the mouth. Oesophageal distension has been shown to be powerful stimulus to parotid secretion (Kay & Phillipson, 1959 flow from the resting gland stopped altogether. This was always due to a plug of mucus blocking the cannula, for when the obstruction was dislodged by gentle massage the flow recommenced.…”