Intestinal Morphology and Cell Production Rate in Aging Rats

Abstract

Age-related changes in the gut were investigated in male gnotobiotic rats, living in a controlled and constant environment until death. Parameters of the regenerative compartment of the jejunum and ileum were the cell production rate (measured by a stathmokinetic technique), the number of crypts, and the crypt:villus ratio. Parameters of the functional compartment were the average surface area of the villi, height and broadness of villi, etc. Age did not change the size of individual villi or crypts or the cell production rate. The number of crypts and, to the same extent, the number of villi increased with age, indicating a continuation of mucosal growth up to an age of 2 yr.

Mucosal surface area in chicken small intestine during development

“…The present results of villus development, expressed as villus amplification factor, suggest significant regional differences during the period considered; the duodenum shows a peak in the third week of age (66% increase with respect to 1-day-old animals), after which it remains unchanged; the jejunum shows a progressive increase, and in the ileum this variable shows few changes. The regional comparison of VAF results agrees with the distal reduction previously described for mammalian species (Wood 1944;Pénzes and Skála 1977;Stenling and Helander 1981;Ecknauer et al 1982;Holt et al 1984;Karasov et al 1986;Thomson 1986;Gardner and Steele 1989) and confirms the data of Levin and Mitchell (1984), who have described for the chicken intestine higher values of villus surface in the jejunum than in the ileum. Smith et al (1990) have attributed the smaller development of ileal villus to the lowest luminal concentration of nutrients that reach this intestinal segment.…”

Morphometric study of the guinea pig small intestine during development

“…The regional pattern detected for 12-week-old guinea pigs, i.e., the highest villus development of the duodenum, has also been described in other mammalian species by several authors (Wood, 1944;Boyne et al, 1966;Barry, 1976;Penzes and Ská la, 1977;Stenling and Helander, 1981;Bastie et al, 1982;Ecknauer et al, 1982;Holt et al, 1984;Karasov et al, 1985;Gardner and Steele, 1989;Mayhew and Carson, 1989). The lower development of ileal villi may be attributed to the lowest luminal concentration of nutrients that reach this intestinal segment (Smith et al, 1990), which is also associated with the regional differences in D-glucose transport (Fisher and Parsons, 1950) and carrier protein density (Buddington and Diamond, 1989).…”

Altered controls of proliferation in proximal small intestine of the senescent rat.

“…Other studies in 19-to 21-month-old Swiss albino mice showed prolongation of the cell cycle but no change in S-phase duration (4,5). In contrast, a study in 24-month-old outbred gnotobiotic Wistar strain rats described a higher number of crypts per unit area of jejunum without a pronounced increase in proliferative activity (6). These experiments often compared immature (growing) and mature (nongrowing) animals and ignored diurnal variations in proliferative rates and the medical, environmental, and nutritional status of the experimental animals.…”