The control of cell number in the lumbar ventral horns during the development of Xenopus laevis tadpoles

Development ◽  
1967 ◽  
Vol 18 (3) ◽  
pp. 359-387
Author(s):  
M. C. Prestige
Keyword(s):  
Xenopus Laevis ◽  
Cell Number ◽  
Ventral Horn ◽  
Early Evidence ◽  
Motor Neurones

The developing limb has been amputated by many workers in several species and in each case the number of surviving motor neurones on the side of the operation was less than normal. This may be observed among the mammals (e.g. Barron, 1945), birds (e.g. Hamburger, 1934), urodeles (e.g. Stultz, 1942), and anurans (e.g. May, 1930). The loss of motor neurones after amputation in adults appears to have been first noticed by Vulpian (1868) and Johnson & Clarke (1868). The early evidence is reviewed by Sherrington (1893) and the later by Piatt (1948). The control that the developing leg has over proliferation, migration, maintenance and degeneration of ventral horn cells has been most completely analysed in the chick, notably by Hamburger (1934, 1939, 1958), Hamburger & Keefe (1944), Bueker (1943, 1944, 1945a), Barron (1946, 1948), Mottet (1952) and Mottet & Barron (1954). Less is known about this in Anura.

The response of the brachial ventral horn of Xenopus laevis to forelimb amputation during development

Development ◽  
1976 ◽  
Vol 36 (3) ◽  
pp. 453-468
Author(s):  
Joanne E. Fortune ◽  
Antonie W. Blackler
Keyword(s):  
Xenopus Laevis ◽  
Normal Development ◽  
Developmental Stages ◽  
Neuronal Degeneration ◽  
Neuronal Loss ◽  
Cell Loss ◽  
Cell Number ◽  
Ventral Horn ◽  
Cell Degeneration ◽  
Cell Numbers

The normal development of the brachial ventral horn of the frog Xenopus laevis and the response of the brachial ventral horn to complete forelimb extirpation at five developmental stages were assessed histologically. Differentiation of brachial ventral horn neurons occurred in pre-metamorphic tadpoles between stages 52/53 and 57. Mean cell number in the brachial ventral horn reached a peak of 2576 (S.E.M. = ±269, n = 2) per side of the spinal cord at stage 55 and decreased to 1070 (S.E.M. = ± 35, n =7) by the end of metamorphosis. Cell degeneration was presumed to be the mode of cell loss since it was most prevalent during the period of rapid decrease in cell numbers. The response of the ventral horn to forelimb removal varied with the stage of the animal at amputation. Following amputation at stage 52/53 or 54 the ipsilateral ventral horn neurons appeared less differentiated than those on the controlside and a rapid cell loss of about 80 % occurred on the operated side. These effects occurred more rapidly after ablation at stage 54 than at stage 52/53. Amputation at stage 58, 61, or 66 caused chromatolysis in the ventral horn, a period of relative cell excess on the operated side, and a delayed neuronal loss of 32–66%. It was concluded that excess cell degeneration accounted for cell loss and that suppression of normal neuronal degeneration caused the relative cell excess on the operated side. The data indicate that the brachial ventral horn was indifferent to the periphery before stage 54, was quickly affected by limb removal between stages 54 and 58, and by stage 58 had entered a phase in which a delay preceded cell death. No forelimb regeneration occurred.

The role of water-regulating mechanisms in the development of the haploid syndrome in Xenopus laevis

Development ◽  
1972 ◽  
Vol 28 (2) ◽  
pp. 449-462
Author(s):  
Louie Hamilton ◽  
P. H. Tuft
Keyword(s):  
Xenopus Laevis ◽  
Cell Number ◽  
Gastrula Stage ◽  
Tail Bud ◽  
Volume Changes ◽  
Membrane Area ◽  
Flow Through ◽  
The Difference ◽  
Haploid Embryos

The uptake of water by haploid and diploid sibling embryos of Xenopus laevis has been investigated by measuring the density changes which occur during the development of intact embryos from the blastula to the late tail-bud stage, and of explants from which most of the presumptive endoderm has been removed. The results show that up to the mid-gastrula stage there is no difference between the haploid and diploid embryos; but from then on, whereas the diploid volume increases steadily, the haploid gastrulae undergo a series of cyclical volume changes due to loss of fluid through the blastopore. It is concluded that this is the result of an excessive inflow of water through the haploid ectoderm, because it was found that the volume of haploid ectodermal explants increased much more rapidly than the volume of similar diploid explants. Excess flow through the haploid ectoderm also accounts for other characteristics of the haploid syndrome – microcephaly and lordosis. It is suggested that it is the doubling of the cell number in haploid embryos with the consequent 25% increase in aggregate cell membrane area which accounts for the difference between the uptake of water by the two types of embryos. It is also suggested that changes in the rate of water flow through the ectoderm and endoderm which are thought to account for the accumulation of water in the blastocoel and archenteron in the normal diploid embryo arise in a similar way.

Retinal growth in double dorsal and double ventral eyes in Xenopus

Development ◽  
1977 ◽  
Vol 40 (1) ◽  
pp. 175-185
Author(s):  
K. Straznicky ◽  
D. Tay
Keyword(s):  
Xenopus Laevis ◽  
Compound Eye ◽  
Ganglion Cells ◽  
Cell Number ◽  
Early Embryogenesis ◽  
Time Points ◽  
Retinal Growth

The growth of normal and surgically produced compound dorsal and ventral retinae in Xenopus laevis has been studied autoradiographically following injections of [3H]thymidine at stages 50 and 58. The animals were sacrificed 3 weeks after metamorphosis. The histogenetic pattern of the dorsal and ventral retinal halves was different at the three time points investigated, i.e. up to stage 50, between stages 50 and 58 and between stage 58 and 3 weeks after metamorphosis. Asymmetrical dorsal retinal growth occurred up to stage 50. From stage 50 onwards the retinal growth tendency reversed so that more ganglion cells were produced along the ventral than the dorsal ciliary margins. The overall preponderance of ventral retinal growth was 32·4% in cell number and 12·4% in retinal length from early embryogenesis to 3 weeks after metamorphosis. The characteristic histogenetic pattern of the dorsal and ventral retinal halves was maintained in an ectopic position in the compound eye, indicating that this particular property of the retinal halves is intrinsically determined.

A quantitative study of the growth and development of the ventral root in normal and experimental conditions

Development ◽  
1974 ◽  
Vol 32 (3) ◽  
pp. 819-833
Author(s):  
M. C. Prestige ◽  
Margaret A. Wilson
Keyword(s):  
Normal Development ◽  
Cell Number ◽  
Ventral Horn ◽  
Ventral Root ◽  
Limb Bud ◽  
Experimental Conditions ◽  
Collateral Sprouting ◽  
Cell Counts ◽  
Ventral Roots ◽  
Fibre Loss

1. The development of the ventral root (VR) in Xenopus has been studied by electron microscopy. Total fibre counts, and counts of classes of fibres were made from large photomontages of the whole of VR 9 at × 15000. 2. The total number of fibres in the root shows the same pattern of initial rise, peak, and subsequent decline that previous ventral horn (VH) cell counts had shown, The two curves overlay each other initially, but after the decline, there were apparently more cells than fibres. 3. Promyelin and myelin formation was seen at the time of the decline. There was no evidence that dying axons had started to myelinate. 4. In some animals the limb-bud was removed at the time of its first penetration by nerve fibres. The ventral roots developed normally for a week, but thereafter fibre loss was accentuated, advanced and more profound, so that after another week, no fibres were left. In these roots, no promyelin or myelin was formed. 5. In other animals, it was shown that there is no evidence for collateral sprouting in the ventral roots during normal development. 6. It is argued that the axons which die in normal development have already reached the limb-bud. 7. The correspondence between axon and cell number is discussed.

Development of the lateral line system in Xenopus laevis

Development ◽  
1983 ◽  
Vol 76 (1) ◽  
pp. 283-296
Author(s):  
Rudolf Winklbauer ◽  
Peter Hausen
Keyword(s):  
Xenopus Laevis ◽  
Lateral Line ◽  
Cell Number ◽  
Fixed Number ◽  
Cell Multiplication ◽  
Second Phase ◽  
Lateral Line System ◽  
Detailed Model ◽  
Line System ◽  
Organ Formation

Cell multiplication was studied during development of the supraorbital lateral line system in Xenopus laevis. The increase in cell number is biphasic. The first phase extends from the beginning of primordial elongation to the end of primary organ formation. Cell number increases linearly during this interval. Throughout this phase, a constant number of cells is in S phase of the cell cycle at a given time, despite a more than 10-fold increase in total cell number. After their formation, the number of the primary organs remains essentially constant. The individual primary organs are not clones of cells. Different organs grow at different rates, and become more and more heterogeneous in size. The second phase which is correlated with accessory organ formation is characterized by an elevated growth rate. This phase was not studied in detail. If developing larvae are starved, growth is normal up to completion of the first growth phase but is arrested at this point. The frequency distribution of the sizes of such growth-arrested organs approximates a binominal distribution. From its characteristics, a detailed model of cell proliferation and organ formation can be deduced: cell multiplication occurs through asymmetrically dividing stem cells, which become allocated to the forming organs at random and go through a fixed number of cell divisions.

scholarly journals Altering nuclear import in early Xenopus laevis embryos affects later development

2019 ◽  
Author(s):  
Predrag Jevtić ◽  
Daniel L. Levy
Keyword(s):  
Xenopus Laevis ◽  
Nuclear Import ◽  
Cell Number ◽  
Early Embryo ◽  
Cellular Functions ◽  
Midblastula Transition ◽  
Developmental Progression ◽  
Importin Α ◽  
Xenopus Laevis Embryos ◽  
Downstream Development

ABSTRACTMore than just a container for DNA, the nucleus carries out a wide variety of critical and highly regulated cellular functions. One of these functions is nuclear import, and in this study we investigate how altering nuclear import impacts developmental progression and organismal size. During early Xenopus laevis embryogenesis, the timing of a key developmental event, the midblastula transition (MBT), is sensitive to nuclear import factor levels. How might altering nuclear import and MBT timing in the early embryo affect downstream development of the organism? We microinjected X.laevis two-cell embryos to increase levels of importin α or NTF2, resulting in differential amounts of nuclear import factors in the two halves of the embryo. Compared to controls, these embryos exhibited delayed gastrulation, curved neural plates, and bent tadpoles with different sized eyes. Furthermore, embryos microinjected with NTF2 developed into smaller froglets compared to control microinjected embryos. We propose that altering nuclear import and size affects MBT timing, cell size, and cell number, subsequently disrupting later development. Thus, altering nuclear import early in development can affect function and size at the organismal level.

The control of cell number in the lumbar spinal ganglia during the development of Xenopus laevis tadpoles

Development ◽  
1967 ◽  
Vol 17 (3) ◽  
pp. 453-471
Author(s):  
M. C. Prestige
Keyword(s):  
Dorsal Root ◽  
Early Stage ◽  
Subsequent Development ◽  
Cell Number ◽  
Limb Bud ◽  
Spinal Ganglia ◽  
Partial Removal ◽  
Motor Neurones ◽  
The Central Nervous System ◽  
Lumbar Spinal

It is the purpose of this paper to describe the development of the lumbar dorsal root ganglia after amputation of the leg. This operation can be performed at a very early stage before any connexions between the limb and the central nervous system are established. Alternatively, it can be performed at a number of later stages after the limb has been innervated. The extent of interaction can then be investigated for each stage by observing the subsequent development of the ganglia and comparing it with that of normal animals. Amputation of the limb-bud or the growing leg results in partial removal of the peripheral field for both sensory and motor neurones; the operation thus provides a means of investigating the mechanisms that control the processes of proliferation, maintenance, and degeneration of nerve cells. Detwiler and his colleagues (Detwiler, 1933) have shown that in Amblystoma loss of cells from the ganglia (hypoplasia) follows amputation, and that increase in number (hyperplasia) follows grafting of a supernumerary limb.

A cytological study of Mauthner's cells in Xenopus laevis and Rana temporaria during metamorphosis

Development ◽  
1968 ◽  
Vol 19 (3) ◽  
pp. 415-431
Author(s):  
J. M. Moulton ◽  
A. Jurand ◽  
H. Fox
Keyword(s):  
Xenopus Laevis ◽  
Rana Temporaria ◽  
Cytological Study ◽  
Nervous Activity ◽  
Special Kind ◽  
Functional System ◽  
Ventral Horn ◽  
M Cells ◽  
Anuran Larvae ◽  
Cytological Changes

This paper discusses cytological changes which occur during anuran metamorphosis in a pair of large hind-brain neurones, the Mauthner cells or M-cells which, in many teleosts and amphibians, innervate the tail musculature via ventral horn cells. The M-cells of fishes, urodeles and anuran larvae are unusually large neurones of particular interest, and according to Stefanelli (1951) they constitute a ‘true functional system of nervous activity’. The value of a cytological study is enhanced by the fact that amphibian M-cells have not yet been extensively analysed biochemically (Deuchar, 1966). In teleosts, the abundant synapses, apparently of a special kind, that terminate on M-cells have been studied by Bodian (1937), Furshpan & Furukawa (1962), Furukawa & Furshpan (1963), Furshpan (1964), Furukawa (1966), Robertson (1963), and Robertson, Bodenheimer & Stage (1963) and have been discussed by Eccles (1964).

The ultrastructure of acinar cells in the external orbital gland of young and old male rats

1978 ◽  
Vol 36 (2) ◽  
pp. 276-277
Author(s):  
R. Carriere
Keyword(s):  
Young Adulthood ◽  
Acinar Cells ◽  
Cell Number ◽  
Male Rats ◽  
Polyploid Cell ◽  
Secretory Cells ◽  
Age Changes ◽  
Albino Rat ◽  
Golgi Membranes ◽  
Diploid Cells

The external orbital gland of the albino rat exhibits both sexual dimorphism and histological age changes. In males, many cells attain a remarkable degree of polyploidy and an increase of polyploid cell number constitutes the major age change until young adulthood. The acini of young adults have a small lumen and are composed of tall serous cells. Subsequently, many acini acquire a larger lumen with an irregular outline while numerous vacuoles accumulate throughout the secretory cells. At the same time, vesicular acini with a large lumen surrounded by pale-staining low cuboidal diploid cells begin to appear and their number increases throughout old age. The fine structure of external orbital glands from both sexes has been explored and in considering acinar cells from males, emphasis was given to the form of the Golgi membranes and to nuclear infoldings of cytoplasmic constituents.

Sign in / Sign up

Export Citation Format

Share Document