Scanning electron microscopy of developing primary endoderm during first 6 hours of incubation in the chick
Article first published online: 26 JAN 2005
Copyright © 1993 Wiley-Liss, Inc.
The Anatomical Record
Volume 235, Issue 1, pages 151–164, January 1993
How to Cite
Low, F. N. and McClugage, S. G. (1993), Scanning electron microscopy of developing primary endoderm during first 6 hours of incubation in the chick. Anat. Rec., 235: 151–164. doi: 10.1002/ar.1092350116
- Issue published online: 26 JAN 2005
- Article first published online: 26 JAN 2005
- Manuscript Accepted: 27 MAY 1992
- Manuscript Received: 4 SEP 1991
- Scanning electron microscopy;
- Chick embryo;
- Developmental biology;
- Intercellular junctions;
Development of primary endoderm in the domestic fowl (Gallus domesticus) is described in scanning electron microscopy (SEM) supplemented by transmission electron microscopy (TEM). Although complicated by great variability, the ventral surface of the blastoderm reveals this process during the first 6 hours of incubation. Primary endoderm arises (1) from the hypoblast, (2) from the margin of the area pellucida, and (3) from intervening protions of the area pellucida. The early hypoblast becomes several cells thick while individual cells are still spherical. TEM reveals a variety of immature cell junctions. During subsequent flattening of these cells into primary endodermal epithelium, numerous filopodia arise from their surfaces. These are 0.20–0.25 μm in diameter. They become long and branched, attaching to each other and to other cell bodies. Similar filopodial processes are present less conspicuously among cells in the margin of the area pellucida. Here, there is pseudopodial evidence that cells or cell sheets creep along the ventral surface of the epiblast. The filopodia disappear as cell flattening proceeds. The ventral surface of the exposed epiblast delaminates cells that become free after their exploratory filopodia and lamellipodia are put forth. Lateral contacts among cell bodies from the above three sources increase until a continuous epithelium is formed. The primary endoderm of the embryo, a simple squamous epithelium that separates the connective tissue space above from the gastrocoele below, is generated by these developmental events. © Wiley-Liss, Inc.