Organogenesis of the colon in rats

Abstract

Colonic organogenesis in rats was studied using light microscopic techniques for the demonstration of mucosubstances, glycogen, and connective tissue fibers. Crypts began as intraepithelial spaces which were in continuity with the colonic lumen. The cells forming the floors of these invaded the nonsulfated acid glycosaminoglycan-rich mesenchyme as the basement membrane became discontinuous. As the diameter of the colon increased, the crypts lengthened and the lamina propria thickened until a layer of collagen and sulfated acid glycosaminoglycans formed at the bases of the crypts and the basement membrane was reestablished. The circular layer of the muscularis externa developed first, then the longitudinal layer, and finally the muscularis mucosae. Three types of mucous cells arose in these newly formed crypts. The initial epithelial cell type contained glycogen and gave rise to cells with apical coats of nonsulfated acid glycoproteins. This cell type was followed by the appearance of cells at the bases of the crypts containing nonsulfated acid glycoproteins. As the crypts lengthened, the goblet cells near the base contained nonsulfated and/or sulfated acid glycoproteins. Closer to and on the surface, the cells contained sulfated acid glycoproteins, a mixture of sulfated acid and neutral glycoproteins, or just neutral glycoproteins. Striated-border cells appeared intermingled with the mucous cells close to the bases of the crypts and continued onto the surface. A comparison was made between regeneration following placement of a surgical lesion in adult rats and events in organogenesis of the colon.

Histogenesis of the mucosa of the descending colon in mouse fetuses.

“…Such is not the case in the descending colon (BRACKETT and TOWNSEND, 1980; the present study). It is possible that the development of the proximal colon occurs in a manner more similar to the small intestine than the distal colon.…”

Expression and location of α-fetoprotein during rat colon development

“…The capability of both up and down modulation of growth and differentiation as a dose-dependent function of AFP has been demonstrated in a multitude of cell types including placental, ovarian, uterine, lymphoid, epidermal, endothelial, testicular, breast, and liver [14][15][16][17][18] . The rat colon undergoes rapid growth and differentiation during the last few days of gestation and the first 2 wk after birth [19][20][21][22] . This maturation process is accompanied by changes in the composition of AFP, which indicates that AFP might be involved in many aspects of colon development.…”

Morphodensitometric analysis of protein kinase C βII expression in rat colon: modulation by diet and relation to in situ cell proliferation and apoptosis

“…This is not entirely atypical, since many biological processes in the proximal and distal colon are distinct (58)(59)(60)(61). For example, distal colonic epithelial cells are derived from a stem cell population at the base of the crypt and migrate from a region of active cell proliferation in the bottom two thirds of the crypt toward the top of the crypt, obtaining a differentiated or apoptotic phenotype (62)(63)(64).…”