Bruce J Crawford

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Early stage embryos of the starfish Pisaster ochraceus exhibit one cilium per cell which is primarily involved in locomotion. SEM observations have demonstrated two types of microvilli "stage horn"-like and "finger-like" microvilli (CMs), both of which probably serve to anchor and support the hyaline layer (HL). The CMs arise from the cellular membrane a(More)
In clonal culture differentiated chick retinal pigmented epithelial (RPE) cells form a monolayer which shows little or no cellular division. The cells usually rest on a basal and reticular lamina and are polarized with their apical surface towards the medium. The apical surface is characterized by apical protrusions, an extensive apical web of(More)
Immunization of rats with gelatin-affinity column purified fibronectin (FN) from rainbow trout (Oncorhynchus mykiss) plasma produced a polyclonal antiserum that reacts specifically with FN in immunoblotted protein extracts and cultured cells, not only from trout but also from swordtails (Xiphophorus helleri). Most importantly, this antiserum specifically(More)
The avian secondary palate exhibits the unique feature of a midline cleft. Cryostat sections indicated that although extensive contact between homologous shelves was present, chick palatal medial edge epithelium (MEE) failed to fuse. The failure of fusion and subsequent clefting of the avian palate were correlated with continued proliferation of the avian(More)
Development of the secondary palate was studied in the chick embryo using light and electron microscopic and histochemical techniques. The palatal shelves develop as horizontal outgrowths of the maxilla on day 6 of incubation (HH stage 29). During the next 2 days (HH stages 30-33) the shelves continue their growth toward the midline, and on day 9 (HH stage(More)
The unfertilized oocyte contains various granules which serve as storage sites for proteins, the majority which are yolk granules or platelets. Yolk granules are thought to provide the developing embryo with nutrients essential for its survival, while other granules contain proteins such as enzymes and extracellular matrix components that are required for(More)
Retinal pigmented epithelium (RPE) from 7-day-old chicken embryos (stages 29 to 31) was isolated and dissociated into single cells using different procedures. The results were assessed in two ways. (1) The yield of single RPE cells per embryo was determined, and their ability to form pigmented colonies in clonal culture was tested. The most efficient and(More)
Anti-PM-2 is a monoclonal antibody that has been developed against the ECM of embryo/larvae of the starfish Pisaster ochraceus. Immunofluorescent staining shows that the PM-2 epitope is present in the cortical granules of unfertilized eggs and is released into the perivitelline space on fertilization. At the blastula stage, staining is very faint and(More)
Distribution and organization of the extracellular glycoproteins, fibronectin and laminin, in clonal cultures of chick retinal pigmented epithelial cells have been investigated using indirect immunofluorescence microscopy. Fibronectin is located on the apical and basal cell surfaces and between the cells in the undifferentiated regions of the colony (outer(More)
When asteroid embryos cryoprotected with propylene glycol are rapidly frozen in liquid propane and freeze substituted with ethanol, preservation of the cells and extracellular matrix (ECM) is excellent. The basal lamina, although thicker and less well defined than in conventionally fixed embryos, demonstrates a region of decreased density just below the(More)