The fine structure of perinotochordal microfibrils in control and enzyme‐treated chick embryos

Abstract

A B S T R A C TMicrofibrils in the notochordal sheath of chick embryos of two to four days incubation age were analyzed electron microscopically. Collagenase, trypsin, hyaluronidase and alpha amylase were administered to both "living" and "fixed" embryos. Living embryos were either explanted on an agar-albumen growth medium or were allowed to survive within the shell during experimental procedures. Fixed embryos were immersed in Karnovsky's aldehyde fixative prior to enzyme digestion. Both living and fixed specimens yielded similar results.Control embryos possessed microfibrils of ca. 200 A, ca. 100 A and less than 100 A in diameter in the notochordal sheath. The smaller fibrils (100 A and less) were present in all regions of the sheath, but were especially concentrated near the notochordal boundary (basement) membrane. The larger fibrils (200 A ) were farther removed from the notochord. Flaky amorphous material was attached to all fibrils and was abundant especially in the inner region of the sheath.Collagenase produced elimination of the 200 A microfibrils, but the smaller ones remained intact. Trypsin caused digestion of all fibrils. Hyaluronidase digested fibrils chiefly 100A and less in diameter. Alpha amylase was similar to hyaluronidase in digesting the small fibrils. This study supports the hypothesis that microfibrils are primarily mucopolysaccharide-protein precursors of larger collagen-rich fibrils.

The morphology of the rostral notochord in embryos of Ichthyophis kohtaoensis (Amphibia, Gymnophiona) is comparable to that of higher vertebrates

“…Different extracellular matrix molecules, mainly proteoglycans and basement membrane proteins, have been identified within the sheath (see for discussion O'Connell and Low 1970;Frederickson and Low 1971;Ruggeri 1972;Carlson and Kenney 1980;Götz et al 1995a, b). A cartilage-like collagen II was likewise found in Xenopus notochordal sheath (Seufert et al 1994) and was proposed to mediate neurocranial morphogenesis.…”

Modulation of hyaluronan in the migratory pathway of mouse primordial germ cells

“…The amount of granules, on the contrary, was constant during the whole migratory process. Cytochemical studies performed in the migratory pathways of bird neural crest cells revealed filaments that were also removed after hyaluronidase treatment (Frederickson and Low 1971;Hay 1978). Similar filaments were observed Table 1 The total length of ruthenium hexammine trichloride-positive filaments per area (3.6 µm 2 ) of the extracellular space of the migratory pathway of mouse embryo primordial germ cells.…”

Macrophage mobilization and morphology during lens regeneration from the iris epithelium in newts: Studies with correlated scanning and transmission electron microscopy

“…Except for seven whole eyes fixed in Bouin's fluid for light microscopy, anterior half-eyes were dissected out and the posterior surface of the iris cleaned with watchmaker's forceps. These freshly dissected tissues were treated with enAbbreviations H enzyme treatment, hyaluronidase only HC enzyme treatment, hyaluronidase followed by collagenase, series two only M macrophage NE no enzyme treatment zymes as follows: (1) no enzyme treatment; (2) testicular hyaluronidase (bovine testis, Sigma type I-S, 500 U/ml) in 80% Dulbecco's PBS (Gibco) at pH 5.2 for 30-45 min at room temperature; (3) hyaluronidase as above followed by a rinse in PBS and treatment with 0.1% collagenase (Clostridium, Sigma type I-A) in 80% Dulbecco's PBS at pH 6.8 for 45-60 min at room temperature (Frederickson and Low, 1971). Following these treatments, the specimens were rinsed in PBS and fixed in Karnovsky's fixative in 0.1 M Na cacodylate buffer at pH 7.3 for 3 h r a t room temperature or 30-90 min at room temperature followed by 4°C overnight.…”