摘要:

AbstractThe study of development and comparisons of the adult structures of the several groups of protochordate animals reveals something of their interrelationships and origin. The hemichordates are perhaps closer to the echinoderms than to the chordates, but these groups appear to have been derived from a bilaterally symmetrical dipleurula ancestor, not from a sessile pterobranch‐like form. The origin of the chordates is speculative but the idea of a prototunicate stage is rejected. The tunicate is viewed as a highly modified end product, with fewer similarities to the ancestral form than amphioxus. Amphioxus is quite suggestive of the vertebrate, yet it is more like the tunicate in the details of its embryology and along with that rather extreme peripheral group is best thought of as constituting a subphylum, the Acraniata.The idea of the early vertebrate as a filter feeder must be rejected since it is assumed here that perfection of that function led to a sessile or inactive way of life (as in the acraniates or lamprey larva) and failed to lead to the active creature with highly developed sensory, neural, and locomotor systems identified here as the protovertebrate. Further, the muscular plastic pharynx and moveable mouth of the protovertebrate suggest feeding on larger organisms, predation, and the abandonment of ciliary water‐current feed

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1973.tb00445.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractA description is given of the neurosecretory system and a possible neuroendocrine system in polychaetes of the families Aphroditidae, Polynoidae and Sigalionidae. Two paired tracts and one unpaired tract of neurosecretory axons, and the ganglionic nuclei from which they arise, have been detected. The neurosecretory tracts are directed to the brain floor where they form a storage‐and‐release complex orneurosecretory neuropile, containing secretion‐laden fibre terminals which are diverse in character and can be distinguished on the basis of staining properties. Bundles of axons (transcapsular fibres) pass through the neurallamella and come into close association with the epithelioid cells of theinfracerebral gland, a possible endocrine structure. The “gland” cells resemble monopolar neuron cell bodies in morphology and are of two types:acells are devoid of secretory material, whereasbcells contain accumulations of PAF‐positive inclusions. Possible simple photoreceptors are associated with part of the cerebral neurosecre

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1973.tb00446.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractThe maculae of the labyrinths of several avian species were examined. Thestriolaof themacula utriculiandlagenaeis tri‐zonal, consisting of two zones of hair cells type I (HC I) located on each side of a middle zone of hair cells type II (HC II). An exception is the mute swan, in which themacula utriculihas astriolaconsisting of one broad zone of HC I.The macula sacculiis, in its central part, mainly consisting of HC I, and thestrioladoes not have a tri‐zonal structure.The hair cells in themacula utriculiare polarized with their kinociliar end oriented towards thestriola, while in themacula sacculiandlagenaethey are oriented away from this dividing line.A varying number, from 1 to 12, of HC I are enclosed within the same nerve chalice. Themacula sacculiseems to contain chalices with slightly more HC I than the two other maculae

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1973.tb00447.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractThe effects on regeneration of serotonin and analagous substances such as tryptamine, DMT, bufotenine, melatonin, auxin and gramine were studied on small pieces ofD. tigrina.By comparison with results obtained in previous works with DOPA, α methyl DOPA and noradrenaline, and also with substances of the series of tetrahydrocannabinol it is shown that the normal morphogenetic action of the neurohormone is dependant of the presence of a free hydroxyl on a flat ring (phenol or indole) and of a free amine on the lateral chain of the molecule. Essays to detect the mechanism of the morphogenetic action did not allow to give any clear conclusion

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1973.tb00448.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractA modified cilium with an adhesive function has been found in an interstitial marine turbellarianParatomella rubra(Acoela). This newly discovered cilium‐type is referred to as a haptocilium; it differs structurally from usual locomotory cilia only in the morphology of the tip. Inside the haptocilial tip is a lamellate, electron‐dense core, and visible outside the ciliary membrane of the tip is an amorphous secretion which is presumably the actual adhesive material by which the haptocilia are able to attach to surfaces. Haptocilia occupy a restricted area, a ventral tail plate, inParatomella.They are motile and display a characteristic slow, irregular b

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1973.tb00449.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractThe copulatory organ ofPantodon buchholziis described. It consists of two folded, complex structures, situated in two pouches, which open ventrally. The wall between the pouches contains the modified skeletal elements of a part of the anal fin. Laterally each pouch is covered by a bony plate. The structures are connected ventrally to the bony plates and consist of a spiral of parallel bone rays, connective tissue with many blood vessels, and covering epithelium. The organ is different from all other copulatory organs described in fishes.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1973.tb00450.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY