Changes in mesenchymal cell and hyaluronate distribution correlate with in vivo elevation of the mouse mesencephalic neural folds

Abstract

The mesenchyme of the elevating mesencephalic neural folds of the mouse is composed primarily of mesenchymal cells embedded in an hyaluronate-rich extracellular matrix. In this study we provide evidence that hyaluronate and mesenchymal expansion may play a role in neural fold elevation and closure. Spatial and temporal patterns of mesenchymal cell and hyaluronate distribution were analyzed during neural fold elevation and closure using the computer-assisted method of smoothed spatial averaging and established methods of image processing. Degree of fold elevation and fold shape changes were analyzed using standard morphometric measures. The results of these analyses defined five distinct stages in mesencephalic neural fold elevation and closure. Mesenchymal cells and hyaluronate were found in a non-random distribution within the neural fold and showed distinct patterns of distribution which could be correlated with specific stages in neural fold elevation. The results of these analyses suggested that the elevation of the mesencephalic neural folds is produced by the expansion of an hyaluronate-rich extracellular matrix in the central mesenchyme which under the direction of surrounding tissues pushes the folds mediad towards the dorsal midline.

twist is required in head mesenchyme for cranial neural tube morphogenesis.

“…Currently, it is generally agreed that abnormalities in the neuroepithelium and non-neuroepithelial tissues can cause neural tube defects (Shoenwolf and Smith 1990). However, only correlative evidence suggesting that head mesenchyme is required for neural tube closure has been reported (Marin-Padilla 1966;Morriss 1972;Morriss and Solursh 1978a, b;Morris-Wiman and Brinkley 1990). Here, we provide direct evidence that head mesenchyme is required for cranial neural tube formation.…”

Effect of Topical Na-Hyaluronan on Hemidesmosome Formation in n-Heptanol-Induced Corneal Injury

“…Immunohistochemical studies also have identified HA-specific receptors in the cornea [25]. HA has been shown to control cell migration and growth, cellular differentiation, and tissue morphogenesis [26][27][28]. These effects of HA should facilitate wound healing and topically applied Na-HA has been reported to protect the surface structure of the corneal epithelium from chemical insult [29], increase the stability of the tear film [3] and enhance the migration of corneal epithelial cells both in vivo [5] and in vitro [6].…”

Bending of the neural plate during mouse spinal neurulation is independent of actin microfilaments

“…The elevating midbrain and hindbrain neural folds are convex, owing to the expanded extracellular matrix of the cranial mesenchyme that underlies the neuroepithelium (Morriss and Solursh, 1978;Morris-Wiman and Brinkley, 1990). Apposition of the cranial neural folds is achieved in a second phase of neurulation in which the edges of the folds bend medially, converging on the dorsal midline (Morriss-Kay, 1981).…”