Die organogenetische und transitorische rolle der vitellophagen in der darmentwicklung von Galathea (Crustacea, Anomura)

Fioroni, Pio

doi:10.1007/bf00282071

Cited by 6 publications

(2 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Gastrulation is epibolic in most species, but some decapod crustaceans show an invagination of cells that develop into midgut and mesoderm with germ cells. This group of cells soon becomes isolated from the ectoderm, at an early stage in Galathea (Fioroni 1970) and at an embryonic stage with appendage buds in Sicyonia (Hertzler and Clark 1992;Hertzler 2002). Stomodaeum and proctodaeum develop in later stages; in Sicyonia the proctodaeum should develop from the area of the closed blastopore.…”

Section: Arthropodamentioning

confidence: 99%

How to make a protostome

Nielsen¹

2012

Invert. Systematics

View full text Add to dashboard Cite

Abstract. The origin and radiation of the major metazoan groups can be elucidated by phylogenomic studies, but morphological evolution must be inferred from embryology and morphology of living organisms. According to the trochaea theory, protostomes are derived from a holoplanktonic gastraea with a circumblastoporal ring of downstream-collecting compound cilia (archaeotroch) and a nervous system comprising an apical ganglion and a circumblastoporal nerve ring. The pelago-benthic life cycle evolved through the addition of a benthic adult stage, with lateral blastopore closure creating a tubeshaped gut. The archaeotroch became differentiated as prototroch, metatroch and telotroch in the (trochophora) larva, but was lost in the adult. The apical ganglion was lost in the adult, as in all neuralians. Paired cerebral ganglia developed from the first micromere quartet. The circumblastoporal nerve became differentiated into a pair of ventral nerve cords with loops around mouth (the anterior part of the blastopore) and anus. Almost all new information about morphology and embryology fits the trochaea theory. The predicted presence of a perioral loop of the blastoporal nerve ring has now been demonstrated in two annelids. Alternative 'intercalation theories' propose that planktotrophic larvae evolved many times from direct-developing ancestors, but this finds no support from considerations of adaptation.

show abstract

Section: Arthropodamentioning

confidence: 99%

How to make a protostome

Nielsen¹

2012

Invert. Systematics

View full text Add to dashboard Cite

show abstract

“…This is a clear example of deuterostomy. Other decapods, such as Galathea squamifera (Fioroni, ), have yolk‐rich eggs and early stages with total cleavage. The nuclei then become situated in small cells at the periphery forming a blastoderm surrounding a large yolk mass.…”

Section: Deuterostomy In Protostomesmentioning

confidence: 99%

Evolution of deuterostomy - and origin of the chordates

Nielsen

2015

Biol Rev

View full text Add to dashboard Cite

The chordates are usually characterized as bilaterians showing deuterostomy, i.e. the mouth developing as a new opening between the archenteron and the ectoderm, serial gill pores/slits, and the complex of chorda and neural tube. Both numerous molecular studies and studies of morphology and embryology demonstrate that the neural tube must be considered homologous to the ventral nerve cord(s) of the protostomes, but the origin of the 'new' mouth of the deuterostomes has remained enigmatic. However, deuterostomy is known to occur in several protostomian groups, such as the chaetognaths and representatives of annelids, molluscs, arthropods and priapulans. This raises the question whether the deuterostomian mouth is in fact homologous with that of the protostomes, viz. the anterior opening of the ancestral blastopore divided through lateral blastopore fusion, i.e. amphistomy. A few studies of gene expression show identical expression patterns around mouth and anus in protostomes and deuterostomes. Closer studies of the embryology of ascidians and vertebrates show that the mouth/stomodaeum differentiates from the anterior edge of the neural plate. Together this indicates that the chordate mouth has moved to the anterior edge of the blastopore, so that the anterior loop of the ancestral circumblastoporal nerve cord, which is narrow in the protostomes, has become indistinguishable. In the vertebrates, the mouth has moved further around the anterior pole to the 'ventral' side. The conclusion must be that the chordate mouth (and that of the deuterostomes in general) is homologous to the protostomian mouth and that the latest common ancestor of protostomes and deuterostomes developed through amphistomy, as suggested by the trochaea theory.

show abstract

Untersuchungen zur Embryologie und Morphologie der GeißelspinneTarantula marginemaculata C. L. Koch (Arachnida, Amblypygi, Tarantulidae)

Weygoldt

1975

Zoomorphologie

View full text Add to dashboard Cite

Die organogenetische und transitorische rolle der vitellophagen in der darmentwicklung von Galathea (Crustacea, Anomura)

Cited by 6 publications

References 20 publications

How to make a protostome

How to make a protostome

Evolution of deuterostomy - and origin of the chordates

Untersuchungen zur Embryologie und Morphologie der GeißelspinneTarantula marginemaculata C. L. Koch (Arachnida, Amblypygi, Tarantulidae)

Contact Info

Product

Resources

About