Differentiation of Enteric Plexuses and Interstitial Cells of Cajal in the Rat Gut During Pre- and Postnatal Life

Abstract

The stomach, small and large intestine of fetuses at term, of unfed newborns, of suckling, weaning and of adult rats were studied by a combined light (LM) and electron microscope (EM) examination. Neuron-specific enolase was used as a neuronal marker under LM. Zinc-iodide-osmium (ZIO) impregnation was used for a selective staining of neurons and interstitial cells of Cajal under both LM and EM. A routine EM procedure made it possible to identify the nerve elements and ICC and to evaluate their degree of differentiation. The differentiation of enteric plexuses and ICC was poor at birth and was accomplished during the weaning period. The myenteric plexus differentiation preceded the submucous plexus differentiation; in particular, under both LM and EM myenteric neurons were already recognizable in the fetus, while the submucous neurons by day 0 under EM and by day 7 under LM. The ICC were poorly differentiated at birth and acquired the adult morphology during the suckling period. Nerve endings contacting ICC were differentiated before ICC differentiation. The ZIO uptake by both nerve elements and ICC correlated with the establishment of their differentiated features. In conclusion, the present findings confirmed that differentiation of ICC and enteric plexuses is microenvironment dependent, since their differentiative steps are interrelated and correlated with diet changes. ZIO impregnation under EM enabled a distinction to be made between a ‘morphological’ and a ‘functional’ differentiation, and revealed that the former is achieved during the suckling period and the latter by the weaning period. It can be suggested that during the postnatal developmental stages ICC and neuronal functions might be different from those in adulthood.

Guide to the identification of interstitial cells of Cajal

“…Moreover, the ZIO method is basically very crude and the selectivity may vary depending on uncontrolled circumstances. With this method it is, however, possible to correlate LM and TEM of the ICC and related nerve endings (Christensen et al, 1987;Faussone-Pellegrini, 1992;FaussonePellegrini and Matini, 1995;Faussone-Pellegrini et al, 1996;Ishikawa and Komuro, 1996;Stach, 1972;Zhou and Komuro, 1995), since ZIOϩ cells are distributed within the muscle coat in a manner identical to that of the ultrastructurally identified ICC and under the TEM are recognizable by their electrondense deposits caused by the ZIO mixture (Fig. 10B).…”

“…Conversely, in the myenteric plexus region of the guinea-pig ileum , one type of fibroblast-like cells was claimed to be ZIOϩ, but distinct from ICC-MGP. Interestingly, it could be demonstrated by electron microscopy that the uptake of ZIO by developing pre-to postnatal ICC in the rat correlates with their degree of differentiation (Faussone-Pellegrini et al, 1996). Lipophilic Carbocyanine Dyes: DiI To allow the visualization of intact ICC in microelectrode studies, vital dyes less photo-sensitive than methylene blue are required.…”

An age-dependent proliferation is involved in the postnatal development of interstitial cells of Cajal in the small intestine of mice

“…ICCs begin to appear during the embryonic period (Torihashi et al 1995;Faussone-Pellegrini et al 1996;Torihashi et al 1997;Ward et al 1997), and the ICC-DMP Wrst appear at the time of birth . ICC-MY are immature at birth both in ultrastructure and physiologic functions (Liu et al 1998).…”

“…ICC-MY are immature at birth both in ultrastructure and physiologic functions (Liu et al 1998). About 2 days after birth, ICC-MY develop ultrastructural features and electrophysiological features that are essentially identical to mature ones (Faussone-Pellegrini et al 1996;Liu et al 1998). Our results show that Kit-positive ICC-MY are loosely interconnected with each other by several slim and very short processes, and a loose cellular network is observed at birth.…”

Numerical metrics for automated quantification of interstitial cell of Cajal network structural properties

“…Similarly, the abundance of processes in the immature ICC networks may not all be necessary or efficient, and throughout maturation the redundant or less effective ones would be discarded. As ICC networks only acquire adult morphology in the suckling period [41], pruning may optimize network performance to accommodate for the increasing work load due to organ growth [38] and maturing dietary influences.…”