摘要:

AbstractThe spermatozoa of two Temnocephalidae collected in Uruguay,Temnocephala iheringiHaswell, 1893 (Host:Pomacea canaliculata) andTemnocephala axenosMonticelli, 1899 (Host:Parastacus varicosus), were studied with a transmission electron microscope. In both species the spermatozoon is made up of a long sperm body which bears at one extremity two free flagella of the 9+‘1’ flatworm pattern. The sperm body contains the nucleus, mitochondria, dense bodies and parallel, cortical, longitudinal singlet microtubules. Along a part of the sperm body the palissade of the microtubules displays a spiral pattern in transverse sections. A part of the perimeter of the cell is thus lined by two overlapping rows of microtubules. This spiral pattern of the singlets is considered as a synapomorphy of the family Temnocephalidae. The singlet microtubules are interconnected by two kinds of links: tangential links between neighbouring singlets in the same row and radial links between singlets belonging to two rows. The presence of these links suggests that this structure could be a motile system of singl

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1987.tb00871.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractIn the last abdominal ganglion of the squat lobsterGalathea strigosa(Decapoda, Anomura) a unique pair of flexor motorneurones exist whose medial cell bodies occur paired either on the ventral or the dorsal surface of the ganglion or else are located separately, one dorsal and the other ventral. In 60 squat lobsters (30 ♂ 30 ♀), this pair of medial dorsal/ventral (MDV) cell bodies was found in 4 distinct cell pair configurations: ventral/ventral, 24; dorsal/dorsal, 5; right ventral/left dorsal, 14; right dorsal/left ventral, 17. MDV cell bodies were never found lying midway between the dorsal and ventral surfaces. The distribution of configurations was approximately the same for both sides of the ganglion and for both sexes, and whether a cell occurred ventrally or dorsally was found to be independent of the position of its partner. The determination of cell body location appears not to be influenced by any cell‐cell interaction, despite an apparent ‘point of close association’ between the two soma neurites and a strong bias overall towards the ventral location (dorsal 1/3, ven

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1987.tb00872.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractColony growth pattern is described inE. pilosa, an abundant cheilostome bryozoan commonly found as an epiphyte ofLaminaria.Each zooid has 4 potential budding loci—one distal, two lateral and one proximal. The ancestrula buds daughter zooids from all of these loci; the two lateral buds appear first, followed by the distal bud and, after a long delay, the proximal bud. The laterally budded zooids curve inwards as they grow to form a triad with their distally budded sibling zooid. ‘Mature’ multiserial colonies growing on flat substrata consist of a series of radially diverging sectors. Each sector has an axis, generally of 3 parallel rows of zooids, flanked by wings consisting of rows of zooids originating as lateral buds from the section axis which infills the area between the axes. Occasional colonies occur with uniserial or semiuniserial growth patterns. These resemble colonies of the obligatory uniserial speciesPyripora catenulariaand poorly fed colonies of the relatedConopeum tenuissimum, which is normally multiserial likeE. pilosa.The ‘composite multiserial’ colonies ofE. pilosadiffer in several respects from ‘unitary multiserial’ colonies characteristic of most sheet‐like cheilostomes, including the well‐knownMembranipora membranacea.Composite and unitary multiserial growth patterns may have evolved independently from un

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1987.tb00873.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractThe actinotroch larva ofPhoronis muellerihas a pair of protonephridia located beneath the tentacle ring and draining the blastocoel; each protonephridium is composed of about 25 solenocytes and a nephroduct which opens in a nephropore on the ventral side of the metasome. The neck of the solenocytes consists of bars, mutually interconnected by a fenestration lamina. Inside the neck microvilli originate proximally in the proximal intrachoanal field and extend through the neck into the nephroduct. There is no canal cell. In cross section the nephroduct is composed of 5–7 monociliary cells, with the cilium protruding through a border of microvilli and extending into the nephroduct. The whole protonephridium is surrounded by a basal lamina. Comparisons of the actinotroch protonephridium with those of other groups have not revealed any convincing homologies. The protonephridia of the protostomians are all considered to be of ectodermal origin, while the cyrtopodocytes ofBranchiostomaare mesodermal. The protonephridium of the actinotroch is ectoderma

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1987.tb00874.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractYoung toads were exposed to a light regimen of 12L/12D at 21°C and fed meal‐worms before hibernation in the autumn, when the toads reduce feeding and discontinue growth, and after hibernation in the spring, when feeding and growth is resumed. In the autumn treatment of the toads with bovine growth hormone maintained feeding and growth; in the spring the treatment protracted the period of feeding and growth. Thyroxin had no obvious effects on growth. It is concluded that the annual growth pattern of temperate zone toads is controlled by an internal rhythm in the secretion of growth hormo

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1987.tb00875.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractThe condition, CI = [body mass (g)/length (cm)3]‐1000, tends to increase in toads growing in the laboratory on a diet of meal‐worms. The allocation was therefore studied of ingested food to growth corresponding to maintenance of standard condition (ΔWS) and to increases in condition, expressing bulky growth. A condition index of 100, typical of toad populations, is chosen to characterize standard growth, higher values expressing bulky growth. The relationship between mass specific standard growth (ΔWs/W0) and actual growth in mass (ΔW/W0) was the same in controls and growth hormone‐treated toads and was independent of sex and season. It could be described by the allometric equation ΔWs/W0= 0.28 (ΔW/W0)1.36,r= 0.93. The composition of mass representing increases in bulk in excess of a CI = 100 was assessed from allometric relationships established between the indices of the chemical constituents and the overall condition index. The increases in condition were partitioned among the organs and parts of the body from allometric relationships established between indices of organs and body parts and the overall condition index. Treatment with growth hormone enhanced growth in mass and significantly increased the relative proportion of mass allocated to standard growth. However, the effect was not specific to growth hormone, but was an indirect effect of the increased growth rate. Water was the predominant constituent of the growth in bulk, amounting to about 70% of increases in CI. Fat and protein contributed about equally initially, 5–10%, with fat strongly increasing and protein slightly decreasing with increasing condition, fat to approach 20–30% when CI approached 200. Increases in water content largely reflected increases in volume of b

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1987.tb00876.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY