The Development of Motor Responses in the Stomach of the Foetal Sheep

Abstract

The state of motor activity of the stomach was studied in a series of foetal sheep. The non-functional period was found to end between the 50th and 60th days of gestation. Sustained activity was preceded by short periods of myogenic and neuromotor activity, and was not in evidence until the 70th day. Foetal swallowing commenced soon after this, but the pattern of suckling behaviour developed gradually over an extended period. The motor mechanisms mediated by the vagus were studied by section and electrical stimulation of the nerve.

Prenatal histomorphological development of the reticulum in fallow deer (Dama dama)

“…By 96 days (40% gestation), the tunica muscularis comprised two muscle fiber layers; an internal obliquely arranged layer and an external longitudinal layer. Similar findings have been reported for sheep by Duncan and Philipson (), Del Rio Ortega () and Franco et al, (). In red deer (Franco et al, ) and goat (García et al, ), a primitive tunica muscularis was observed at an earlier stage (25% gestation).…”

“…By 96 days (40% gestation), the tunica muscularis comprised two muscle fiber layers; an internal obliquely arranged layer and an external longitudinal layer. Similar findings have been reported for sheep by Duncan andPhilipson (1951), Del Rio Ortega (1973) and Franco et al, (1993b).…”

Development of Digestive Motor Patterns During Perinatal Life

“…The trophic role of amniotic fluid in the development of the gastric mucosa , including the parietal cell s, and in overall gastrointestin al grow th, has been recently shown by es ophagea l ligation studies in 28-day-old rabbit (24). Such a role is also likely in the 80-day-old fet al lamb in which stimul ation of the perioral region is accomp anied by gastric filling (25). The daily swallowing of 150-350 ml (26) or more (27) of amniotic fluid in 2.5-3-kg ovine fetu ses near term is accompanied during the last week of prenatal life b y a reduced inhibition of pro staglandin synthesis (28).…”

Restitution of Swallowing in the Fetal Sheep Restores Intestinal Growth after Midgestation Esophageal Obstruction

“…It is likely that ingestion of fluid by the ovine fetus begins as early as 60 days of gestation (11), which is at least 30 days earlier than when we fistulated the esophagus in our earlier studies (6,7). Thus, in our earlier studies, the GIT had already been exposed to a considerable volume of swallowed fluid, and the effects we noted could have been the result both of reduced GIT growth rates and abnormal growth patterns as a result of tissue atrophy and adaptation.…”

“…An aim of this study was to clarify this issue by maximizing the impact of the absence offetal ingestion. To do this, we ligated the esophagus as early as was surgically practicable (between 60 and 70 days" gestation), soon after the onset of swallowing (11), and determined the effects on GIT development near term (136 days). A second aim of this study was to determine whether deficits in GIT development caused by esophageal obstruction could be reversed at a later stage of gestation by restitution of fetal swallowing.…”