摘要:

AbstractThe genital morphology of femalePholcus phalangioidesis examined to clarify the composition of the uterus externus and the place of sperm storage in this species. Two conspicuous pore plates serve as exits for glandular secretion that gets discharged into the uterus externus. The secretion accumulates close to the pore plates and to some extent in the region of the heavily sclerotized valve that separates the uterus externus from the uterus internus. During copulation, the male transfers spermatozoa and male secretions into the female genital tract where they are embedded and stored in the female secretion. AsPh. phalangioidesdoes not possess any separate sperm storage organs such as receptacula seminis, the glandular secretion serves to store and fix the sperm mass in a specific position within the uterus externus itself.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1994.tb00957.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractPholcus phalangioidesdoes not possess receptacular seminis. The uterus externus (genital cavity) itself functions as a sperm storage structure. Two accessory glands are situated in the dorsal part of the uterus externus; they discharge their secretory product into the genital cavity.The secretion is considered to serve primarily as a matrix for sperm storage, i.e. to keep the spermatozoa in a fixed position.The accessory glands consist of numerous glandular units, each being composed of four cells: two secretory cells are always joined and surrounded twice by an inner and an outer envelope cell. Both envelope cells take part in forming a cuticular ductule that leads from the secretory cells to the pore plates of the uterus externus. The inner envelope cell produces the proximal part of the canal close to the microvilli of the secretory cells, whereas the outer envelope cell produces the distal part of the canal leading to the pore plate. Close to the pore the latter exhibits prominent microvilli that might indicate additional secretory activity.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1994.tb00958.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe morphological evolution of the cutaneous venom during ontogenesis in the tree‐frogHyla arborea arboreais described using light and electron microscopy. Venom biosynthesis involves the rough endoplasmic reticulum and Golgi stacks. The secretory product first appears at the hind‐limb larval stage in the form of aggregates of small granules or larger, more elaborate structures, both contained in Golgi stacks. Maturative evolution proceeds through the merging of these secretion storage bodies and leads to the remarkable morphological heterogeneity characteristic of the venom of premetamorphic larvae and juveniles. However, large structures, resulting from the aggregation of small granules arranged in a repeating pattern become the only secretory accumulation bodies found in fully developed glands. In juveniles, discrete amounts of venom were seen to be discharged through exocytosis into the exiguous gland lumen, which lies just beneath the intercalated tract. These findings strongly contrast the traditional pattern of holocrine release characteristic of anuran serous glands. The merocrine release of tiny venom particles is consistent with the regulative roles—relevant to the skin physiology—performed by component molecules of anuran cutaneous

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1994.tb00959.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe structure and function of the captaculum inGraptacme calamuswere studied using light microscopy, videomicrography, and transmission electron microscopy.Graptacme calamusutilizes a longitudinal ciliary band to transport small food particles along the outstretched filament. The head of the captaculum, which bears the alveolar indentation, contains a large ganglion, at least three types of gland cells, circular and longitudinal muscles, and connective tissue. It is likely that gland 1 secretes mucus which is used in the transport of food particles and that gland 2 secretes material which promotes adhesion of the alveolus to the substratum. The function of gland 3 is unknown. Critical observation of the captaculum surface revealed that the cilia of the alveolar region have truncated tips unlike those found on other regions of the captaculum. These alveolar cilia probably aid in the distribution of adhesive substance and in adhesion.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1994.tb00960.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe ultrastructure of the central nervous system of four species of theGeocentrophoragroup (Prorhynchida, Lecithoepitheliata) has been studied withGeocentrophora waginias a model organism. This is the first ultrastructural study of the nervous system in flatworms of the endemicGeocentrophoragroup from Lake Baikal.The neurons are characterized by invaginations of the plasma membrane with extracellular material (ECM) extending deep into the neuronal cytoplasm. Two types of neuron are distinguished on the basis of the character of the cytoplasm and the content of neuronal vesicles. Several more vesicle types are observed in the nerve processes in the neuropile.The following kinds of neuronal release sites are distinguished: single synapses, shared synapses, nonsynaptic release sites characterized by omega profiles and neuromuscular contacts. Special features of the synapses in the species ofGeocentrophoraare pronounced local thickenings of the presynaptic membrane connected to paramembraneous densities. The ECM‐filled invaginations and the local presynaptic thickenings are features that distinguish the neurons ofGeocentrophoraspp. from previously described turbellarian neuron

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1994.tb00961.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractUsing SEM and TEM techniques, the trichobothria ofAcrogalumna longipluma(Galumnidae, Pterogasterina) were studied in relation to a variety of other moss mites. Each sensillum is composed of a mostly solid bothridial seta and a very complex socket, the bothridium. The setal base bends sharply as it passes through the six chambers of the bothridium, which are arranged in an S‐shaped configuration. The proximal end of the seta is an elongated oval and inserted into a thin socket membrane provided with radiating suspension fibres. This peculiar shape of the setal base proper and probably also the existence of connecting pieces are assumed to provide directionality to the sensillum. Two differently shaped tubular bodies are found under the setal base, of which only one is in contact with the seta. The tubular bodies are surrounded by peculiar ‘dense tubes’, i.e. derivatives of the dendritic sheath. The rather thick, outer dendritic segments curve through an extensive receptor lymph cavity and terminate with ciliary regions. The inner dendritic segments are only short. Perikarya and axons as well as the enveloping cells do not show any peculiarities. The trichobothria of moss mites most probably represent vibration receptors reacting to substrate and/or air‐borne stimuli. The variety of shapes and the complexity, which is not found to this extent in any other arthropod group, are discussed in relation to ecophysiological

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1994.tb00962.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe structure and organization of the organic matrix of the cusps of the major lateral teeth of the chitonAcanthopleura hirtosahave been examined using conventional light and transmission electron microscopy techniques and by using the protein ferritin as an ultrastructural probe. The results show major structural differences in the organic matrix between the surface layers of the anterior (calcified) region and the posterior (magnetite‐mineralized) region and their respective underlying regions. In addition, the central (lepidocrocite‐mineralized) region of the tooth has been examined and shown to consist of bundles of fibres arranged such that they display a tightly interwoven pattern. It is suggested that while the structural organization of surface fibres readily permits the passage of ions required for mineralization, the architecturally discrete distribution of biominerals found in mature chiton teeth is due mostly to spatial delineation of the tooth by matrix macromolecules in the central region of the to

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1994.tb00963.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY