Extracellular matrix synthesis in the chick embryo lateral plate prior to and during limb outgrowth

Little is known at the present time about the molecular basis and mechanisms of morphogenesis. The present study is an attempt to determine what influence the extracellular matrix has on the initial outgrowth of the limb bud. Stage -12 to -18 chick embryo lateral plates were examined in relation to proline and sulfate incorporation into collagen and proteoglycan. The flank and limbs incorporated the same amount of labeled proline and sulfate before stage 16. At stage 16 the flank began to incorporate more of both isotopes until at stage 18 there was twice as much incorporation into the flank as into the limbs. The flank and limbs contained the same type of collagen during the period examined. The limbs contained both large and small proteoglycans but the flank contained only small proteoglycans. These data suggest that the extracellular matrix in the flank and limb regions may play a role in limb outgrowth and that the limb buds at these stages may be more inclined toward cartilage development.

Download Full-text

The stages of flank ectoderm capable of responding to ridge induction in the chick embryo

Development ◽

10.1242/dev.84.1.19 ◽

1984 ◽

Vol 84 (1) ◽

pp. 19-34

Author(s):

Jill L. Carrington ◽

John F. Fallon

Keyword(s):

Chick Embryo ◽

Early Stage ◽

Limb Bud ◽

Substantial Proportion ◽

Wing Development ◽

Limb Outgrowth ◽

Wing Bud ◽

Two Stages ◽

Inductive Signals

Reports on the stages when chick flank ectoderm can respond to ridge induction are contradictory. Different results have been obtained using presumptive wing or leg bud mesoderm as the inducing tissue with flank ectoderm as the responding tissue. In addition, although incomplete outgrowths have been obtained from recombinants with stage-19 flank ectoderm in a small percentage of cases, no complete outgrowths have been obtained from recombinants with ectoderm older than stage 18. We reinvestigated when chick flank ectoderm can respond to ridge induction and promote outgrowth of complete limbs. To do this, we combined flank ectoderm with in situ chick presumptive wing bud mesoderm using a pre-limb bud recombinant technique. When presumptive wing bud ectoderm was removed from the host and not replaced, wing development was suppressed. When host ectoderm was replaced with stage-15 through -18 chick flank ectoderm, limbs grew out in all cases; 86·% of these recombinant limbs were distally complete. Stage-19 flank ectoderm formed a ridge and promoted limb outgrowth in 80·9% of recombinants; 52·9% of these were distally complete limbs. Recombinants made by grafting early stage-20 (40-somite donor) flank ectoderm to stage-15 hosts resulted in outgrowths in 60% of the cases and 33·3% of these were distally complete. Graft ectoderm from older donors did not respond to inductive mesoderm. Our results demonstrate that chick flank ectoderm from stage-15 through early stage-20 donors can respond to inductive signals from presumptive wing bud mesoderm to form an apical ridge. This ridge can promote outgrowth of distally complete wings in a substantial proportion of recombinants. This is two stages beyond when the ability to promote outgrowth of distally complete wings appeared to be lost using other methods.

Download Full-text

The distribution of the polarizing zone (ZPA) in the legbud of the chick embryo.

Development ◽

10.1242/dev.86.1.169 ◽

1985 ◽

Vol 86 (1) ◽

pp. 169-175

Author(s):

J. Richard Hinchliffe ◽

Anna Sansom

Keyword(s):

Pattern Formation ◽

Chick Embryo ◽

High Activity ◽

Posterior Margin ◽

Posterior Part ◽

Limb Bud ◽

Limb Buds ◽

Anteroposterior Axis ◽

Low Activity

The stage-21 to 22 legbud polarizing zone (ZPA) was mapped by transplanting small blocks of posterior marginal mesenchyme preaxially into stage-20 to -22 chick wing buds and assessing the degree of duplication of the wing digital skeleton produced in the host. Blocks taken from the posterior flank, from the angle between posterior flank and the proximal base of the limb bud, and from the most anterior distal position chosen (under the AER), all had very low activity. Blocks taken from the posterior margin of the legbud, plus the next distal block under the posterior part of the AER, all had high activity. We consider that barrier and amputation results on wing and legbud, when interpreted in the light of maps of the ZPA in both limb buds, are consistent with the hypothesis that both leg and wing have their growth and anteroposterior axis of pattern formation controlled by the ZPA.

Download Full-text

Apical ridge dependent and independent mesodermal domains of GHox-7 and GHox-8 expression in chick limb buds

Development ◽

10.1242/dev.116.3.811 ◽

1992 ◽

Vol 116 (3) ◽

pp. 811-818 ◽

Cited By ~ 11

Author(s):

M.A. Ros ◽

G. Lyons ◽

R.A. Kosher ◽

W.B. Upholt ◽

C.N. Coelho ◽

...

Keyword(s):

Pattern Formation ◽

Limb Development ◽

Apical Ectodermal Ridge ◽

Limb Bud ◽

Rapid Decline ◽

Limb Buds ◽

Limb Outgrowth ◽

Removal Experiments ◽

The Relationship

The homeobox-containing genes GHox-7 and GHox-8 have been proposed to play fundamental roles in limb development. The expression of GHox-8, by the apical ridge cells, and GHox-7, in the subridge mesoderm, suggests the involvement of these two genes in limb outgrowth and proximo-distal pattern formation. A straightforward way to test this is to remove the apical ridge. Here we report the relationship between the mesodermal expression of GHox-7 and GHox-8 and the apical ectodermal ridge in the chick limb bud. The data from ridge removal experiments indicate that there are at least two domains of GHox-7 expression in the apical limb bud mesoderm. The posterior subridge GHox-7 domain in the progress zone requires the influence of the apical ridge for continued expression, while the anterior GHox-7 domain continues expression after ridge removal. Posterior subridge mesoderm is exquisitely sensitive to the loss of the ridge in that GHox-7 expression by these cells is reduced in only two hours and undetectable by three hours after ridge removal. It would appear that one of the ways progress zone cells respond to the apical ridge signal is by expressing GHox-7. The loss of ridge influence whether by growth at the apex or by ridge removal is followed by an unusually rapid decline in detectable GHox-7 transcripts. Maintenance of GHox-8 expression by the anterior mesoderm appears to be independent of the presence of the apical ridge.(ABSTRACT TRUNCATED AT 250 WORDS)

Download Full-text

The distribution of endogenous retinoic acid in the chick embryo: implications for developmental mechanisms

Development ◽

10.1242/dev.125.21.4133 ◽

1998 ◽

Vol 125 (21) ◽

pp. 4133-4144 ◽

Cited By ~ 4

Author(s):

M. Maden ◽

E. Sonneveld ◽

P.T. van der Saag ◽

E. Gale

Keyword(s):

Retinoic Acid ◽

Chick Embryo ◽

Neural Tube ◽

Cell System ◽

Limb Bud ◽

Lateral Plate ◽

F9 Cells ◽

Chick Embryogenesis ◽

Wide Range ◽

Very High

The aim of these experiments was to determine the endogenous distribution of retinoic acid (RA) across a wide range of embryonic stages in the chick embryo. By high pressure liquid chromatography, it was revealed that didehydroRA is the most prevalent retinoic acid in the chick embryo and that the tissues of the stage 24 embryo differed widely in their total RA content (didehydroRA + all-trans-RA). Some tissues such as the heart had very little RA and some such as the neural tube had very high levels, the total variation between these two being 29-fold. We showed that these tissues also synthesised RA and released it into the medium, thus validating the use of the F9 reporter cell system for further analyses of younger staged embryos. With these F9 cells, we showed that, at stage 4, the posterior end of the embryo had barely detectably higher levels of RA than the anterior end, but that a significant level of RA generation was detected as soon as somitogenesis began. Then a sharp on/off boundary of RA was present at the level of the first somite. We could find no evidence for a posterior-to-anterior gradient of RA. Throughout further development, various consistent observations were made: the developing brain did not generate RA, but the spinal part of the neural tube generated it at very high levels so there must be a sharp on/off boundary in the region of the hindbrain/spinal cord junction; the mesenchyme surrounding the hindbrain generated RA whereas the hindbrain itself did not; there was a variation in RA levels from the midline outwards with the highest levels of RA in the spinal neural tube followed by lower levels in the somites followed by lower levels in the lateral plate; the posterior half of the limb bud generated higher levels than the anterior half. With these observations, we were able to draw maps of endogenous RA throughout these early stages of chick embryogenesis and the developmental implications of these results are discussed.

Download Full-text

The origin and movements of the hepatogenic cells in the chick embryo as determined by radioautographic mapping

Development ◽

10.1242/dev.25.1.97 ◽

1971 ◽

Vol 25 (1) ◽

pp. 97-113

Author(s):

Glenn C. Rosenquist

Keyword(s):

Chick Embryo ◽

Developmental Stage ◽

Primitive Streak ◽

Limb Bud ◽

Chick Embryos ◽

Lateral Plate Mesoderm ◽

Lateral Plate ◽

Somite Stage ◽

Definition Of ◽

Exact Definition

The origin of the prehepatic cells was determined by tracing the movements of [3H]thymidine-labelled grafts excised from medium-streak to 4-somite stage chick embryos and transplanted to the epiblast, streak and endoderm-mesoderm layer of similarly staged recipient embryos. Although exact definition of prehepatic areas was not possible because of the small number of grafts placed at each developmental stage, the study showed in general that at the medium-streak stage, the prehepatic endoderm cells are in the anterior third of the primitive streak; they shortly begin to migrate anteriorly and laterally into the endoderm layer ventral to the precardiac areas of mesoderm. They are in the yolk-sac endoderm at the 2–4-somite stage, and by the 15–17-somite stage are clustered at the anterior intestinal portal. At the 26-somite to early limb-bud stages, the anterior and posterior liver diverticula have formed from these endoderm cells, and some of the branches of the diverticula may have reached the prehepatic mesenchyme, where the two tissues have begun to form cords and sinuses. At the medium-streak stage, the prehepatic mesoderm is located slightly more than halfway from the anterior to the posterior end of the primitive streak. From this position it migrates anteriorly and laterally into the lateral plate mesoderm, and from the head-process to the 2–4-somite stage it is situated posterior to the prehepatic endoderm and posterior and lateral to the heart-forming portion of the splanchnic layer. By the 15–17-somite stage the prehepatic mesoderm has reached a position in the splanchnic layer of mesoderm which forms the dorsolateral wall of the sinus venosus. By the 26-somite to early limb-bud stage the hepatic diverticula have joined with the hepatic mesenchyme to form the rudimentary cords and sinuses of the liver.

Download Full-text

IGF-I, insulin and FGFs induce outgrowth of the limb buds of amelic mutant chick embryos

Development ◽

10.1242/dev.122.4.1323 ◽

1996 ◽

Vol 122 (4) ◽

pp. 1323-1330 ◽

Cited By ~ 2

Author(s):

C.N. Dealy ◽

R.A. Kosher

Keyword(s):

Proper Time ◽

Limb Bud ◽

Chick Embryos ◽

In Vitro Morphogenesis ◽

Limb Buds ◽

Limb Outgrowth ◽

Igf I ◽

High Level

IGF-I, insulin, FGF-2 and FGF-4 have been implicated in the reciprocal interactions between the apical ectodermal ridge (AER) and underlying mesoderm required for outgrowth and patterning of the developing limb. To study further the roles of these growth factors in limb outgrowth, we have examined their effects on the in vitro morphogenesis of limb buds of the amelic mutant chick embryos wingless (wl) and limbless (ll). Limb buds of wl and ll mutant embryos form at the proper time in development, but fail to undergo further outgrowth and subsequently degenerate. Wl and ll limb buds lack thickened AERs capable of promoting limb outgrowth, and their thin apical ectoderms fail to express the homeobox-containing gene Msx-2, which is highly expressed by normal AERs and has been implicated in regulating AER activity. Here we report that exogenous IGF-I and insulin, and, to a lesser extent, FGF-2 and FGF-4 induce the proliferation and directed outgrowth of explanted wl and ll mutant limb buds, which in vitro, like in vivo, normally fail to undergo outgrowth and degenerate. IGF-I and insulin, but not FGFs, also cause the thin apical ectoderms of wl and ll limb buds to thicken and form structures that grossly resemble normal AERs and, moreover, induce high level expression of Msx-2 in these thickened AER-like structures. Neither IGF-I, insulin nor FGFs induce expression of the homeobox-containing gene Msx-1 in the subapical mesoderm of wl or ll limb buds, although FGFs, but not IGF-I or insulin, maintain Msx-1 expression in normal (non-mutant) limb bud explants lacking an AER. The implications of these results to the relationships among the wl and ll genes, IGF-I/insulin, FGFs, Msx-2 and Msx-1 in the regulation of limb outgrowth is discussed.

Download Full-text