title: A freeze-fracture study of perinatal changes of intramembranous particles in microvilli of absorptive cells in mouse small intestine.
abstract: Perinatal changes in the appearance of intramembranous particles (IMPs) of microvilli of enterocytes were analyzed quantitatively. In both the jejunum and the ileum, the IMP density on the P-face showed no significant changes from day 17 of gestation to day 5 of postnatal life. It increased between day 5 and day 12, reached a maximum at day 21, and thereafter decreased slightly. The IMP density on the E-face remained almost constant during the perinatal period in both intestinal parts. Measurements of particle diameters proved that neither the P-face nor the E-face membrane showed significant differences in either mean value or size distribution among different age groups. This study has revealed that the perinatal change in the IMP density on the P-face of microvilli correlates well with changes in the activity of certain enzymes found in the membranes of microvilli, e.g. disaccharidase and aminopeptidase.
mesh_terms: D000469:Alkaline Phosphatase / Q000032:analysis; D000626:Aminopeptidases / Q000032:analysis; D000818:Animals; D000831:Animals, Newborn / Q000033:anatomy & histology; D005333:Fetus / Q000648:ultrastructure; D005614:Freeze Fracturing; D007421:Intestine, Small / Q000648:ultrastructure*; D051379:Mice; D008871:Microvilli / Q000201:enzymology / Q000648:ultrastructure*
chemical_list: D000469:Alkaline Phosphatase; D000626:Aminopeptidases