- Collection:
- Atlanta University and Clark Atlanta University Theses and Dissertations
- Title:
- Factors affecting the loss of morphogenetic competence by chick limb mesoderm cells during suspension culture, 1987
- Creator:
- Donald, Melody R.
- Date of Original:
- 1987-05-01
- Subject:
- Degrees, Academic
Dissertations, Academic - Location:
- United States, Georgia, Fulton County, Atlanta, 33.749, -84.38798
- Medium:
- theses
dissertations - Type:
- Text
- Format:
- application/pdf
- Description:
- The present study was designed to provide further information concerning the mechanism underlying the loss of morphogenetic competence by stage 20 and 22 (Hamburger and Hamilton, 1951) chick leg-bud mesodermal cells in suspension culture and the relationship of this loss to the parallel loss which occurs in vivo. Stage 20 cells exposed to suspension culture for 1,8,12,18, and 24 hours and stage 22 cells exposed for 4,10, 15, and 24 hours showed a decline in the number of cells recovered (due to cell lysis or loss into aggregates). Dissociating the aggregates of cells that formed during suspension culture and plating in micromass cultures for 4 days to detect histogenic capacity, revealed that these cells were morphologically chondrogenic or fibroblast-like (as determined from Alcian blue staining and light microscopy). The stage 20 limb cells placed in suspension culture for 1 to 8 hours were fibroblast-like. However, after 12 to 24 hours, the stage 20 cells formed aggregates that differentiated into cartilage nodules after 4 days in micromass culture. The highest average number of single countable nodules was seen by 18 hours in suspension culture followed by 4 days in micromass plate culture. The stage 22 trypsin-EDTA dissociated cells had a greater capacity for expressing chondrogenesis following suspension culture than the stage 20 limb cells for all time periods tested. The stage 22 limb cells do not show a direct relationship between cell aggregation during suspension culture and cartilage differentiation in micromass culture as detected with stage 20 limb cells. The highest average number of single countable cartilage nodules was detected after 4 hours of suspension culture followed by 4 days in micromass culture. The stage 22 EGTA dissociated limb cells were more chondrogenic than their controls which were fibroblast-like for all time periods tested. The culture medium was altered for this study to reduce the number of additives. This alteration affected the histogenic capacity of the control cells by inhibiting their chondrogenic capacity from occurring. Thus, it appears that placing the cells in suspension culture overcame the inhibitory action of factors in the culture medium. Under this condition, the highest average number of single countable cartilage nodules was detected after 4 hours of suspension culture followed by 4 days in micromass culture. The results of these studies suggest that placing cells in suspension culture causes cell loss due to lysis and cell aggregation and selects for chondrogenic cells in the remaining population. The conclusion is drawn that further studies must be done to determine how the selection for chondrogenic cells occurs and the specific effects on the morphogenetic competence of the surviving cells.
Degree type: thesis
Degree name: Master of Science (MS)
Granting institution: Atlanta University
Department: Department of Biology
Advisor: Paulsen, Douglas F. - Metadata URL:
- http://hdl.handle.net/20.500.12322/cau.td:1987_donald_melody_r.pdf
- Holding Institution:
- Atlanta University Center Robert W. Woodruff Library
- Rights:
-
