On the Histology and the Innervation of the Oesophagus and the First Forestomach of Goat

Abstract

Longitudinal mucous folds in the oesophagus in goat are found only in its lower parts. The epithelium there is of thick stratified flat nature and regularly arranged small papillae grow into it from the very thin propria mucosae. The longitudinal muscularis mucosae is only poorly develped in the lower oesophagus. The submucosa contains much fat tissue, but the blood vessels therein are very ill developed, perhaps owing to the absence of oesophageal glands. The tunica muscularis of striated muscle fivres consists of an inner longitudinal and an outer circular layers, which grow somewhat thicker downwards, but in the lowest part of the oesophagus, the direction of the muscle fibres is exchanged, fibres in the inner layer running circularly and those in the outer layer longitudinally, another layer of circular smooth muscle fibres is formed inside the inner layer above.
The first forestomach or the rumen of goat is provided with few folds on its mucous membrane but stomach papillae resembling those on the tongue are formed on it. The epithelium here is a stratified flat one, only 1/3-1/4 of that in the oesophagus in thickness. The papillary formation from the propria into the epithelium is good in the stomach papillae but inferior in other parts. Lamina muscularis mucosae is also anything but well developed, being utterly absent outside the incipient part of the rumen. The submucosa containing neither fat tissue nor mucous glands, the blood vessels here are very ill developed. The tunica muscularis contains some striated fibres in the incipient part, but in other parts, these fibres are replaced by smooth muscle fibres and the tunica comes to consist of thin inner circular and outer longitudinal layers.
Of the nerve fibres coming into the oesophagus, the somatomotor fibres accounting for the largest majority and originating in the n. accessorius end in motor endplates.
The vegetative fibres entering the oesophagus comprise sympathetic and vagal parasympathetic fibres and first run into the AUERBACH's plexus, which is very poorly developed, for the number of the vegetative fibres for the goat's oesophagus is much smaller than that for the gullets of man and other animals containing numerous smooth muscle fibres. In the lower oesophagus of goat, however, the AUERBACH's plexus contains some small ganglia. The MEISSNER's plexus in the submucosa is also very ill developed, containing no nerve cell.
The ganglion cells in the AUERBACH's plexus are mostly of the DOGIEL's Type I, but the development of their nerve processes is very inferior. The vegetative fibres always end in STÖHR's terminal reticula, particularly in good formation in the muscularis mucosae.
Thick sensory fibres originating in the n. vagus are found distributed in the oesophagus of goat too. These run first to the AUERBACH's plexus, a part of them ending here, but the majority run further into the submucosa and form their terminations spreading thence into the propria from the muscularis mucosae. These sensory fibres are found in a larger number and show somewhat more complex terminal mode in goat than in dog and snapping turtle, but no such high-class glomerular or complex branched terminations as found in the human oesophagus were ever found in goat.
The sensory terminations in the AUERBACH's plexus consist in specific branched terminations with their rather numerous thick terminal fibres running peculiar looped courses while showing frank change in size spread out over rather wide areas. The sensory terminations in the propria, however, are merely of simple branched type, and comprise those with little winding terminal fibres and those with peculiarly winding terminal fibres (the so-called snake-like terminations). The terminal fibres run up very close to the underside of the epithelium but never further into it.
In the incipient part of the rumen, where the tunica muscularis is well developed