摘要:

AbstractScanning and transmission electron microscopic investigations of the epidermal surface cells, the small mucous cells, ofMyxine glutinosareveal specific structural differentiations in the form of vertical apical channels with microvilli and supporting tonofilament skeleton. The functional significance of these surface differentiations with regard to the living environment ofMyxineis discussed and a comparison with the surface characteristics of other aquatic animals is drawn.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1982.tb00776.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractFoetuses of reindeer,Rangifer tarandus tarandusL., were collected at slaughter and studied for structural primordial stages of pedicle formation and antler growth. Fresh foetuses studied in January and February exhibited a round, pale area with an epidermal infolding or groove at the site of the future antler development. Also, in an ethanol‐fixed caribou foetus from Alaska, an epidermal invagination could be seen in the area of later pedicle formation. No protruding bone or cartilage was observed as primordial stages of antler growth in reindeer foetuses collected from 10 November to 26 April. It is concluded that an epidermal infolding exists in the foetus of telemetacarpal cervids such as reindeer and caribo

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1982.tb00777.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractThe labial and maxillary palps of the bark beetle,Ips typographus, possess a diversified array of sensilla. There are four types of sensilla possessing a single tubular body indicating a mechanoreceptive function. The variation of the associated cuticular structures of these sensillar types ranges from long bristles to cavities within the cuticle. Terminal pore sensilla with a supposed mechanosensory/gustatory function and single‐walled presumably chemoreceptive sensilla are found on the apical part of the terminal palp segments. A poreless sensillar type is found on the lateral side of the terminal segment of the maxillary palp. The functional capabilities of this sensillar type are presently unknow

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1982.tb00778.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractMyriothela cocksi.a solitary athecate hydropolyp showing many peculiarities and being well investigated concerning gonophore development and embryology, has up to now hardly been examined in respect to regeneration. The simple experiments performed here demonstrate the capacity of all three body regions to regenerate, in due time, previously amputated parts entirely. Further, they reveal a clearly two‐phased regeneration process. The first phase leads to a repaired wound, the second results in a rebuilding of the missing part. Ecto‐ and endoderm are differently involved in regeneration. A greater importance of the endoderm for the first stages of regeneration has been found. Finally, the experiments prove an existing polarity in the polyp. On the basis of these findings it can be concluded that the polyp meets the major criteria of regeneration. This is an absolutely necessary presupposition for all further experime

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1982.tb00779.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractThe ampullary organs of the bichir were examined by light and electron microscopy. Unlike most other ampullary organs, they are exclusively found in the epidermis and are never sunk into the subepidermal connective tissue. The sensory epithelium consists of sensory cells and supporting cells surrounded by mantle cells. The luminal surface of the sensory cell is provided with a cilium surrounded by several microvilli. In the apical cytoplasm are found numerous mitochondria and microtubules. In the basal part of the cell synaptic sheets or synaptic bodies opposite to afferent nerve endings are frequent.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1982.tb00780.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractTo study direct action of thyroxine (T4) on duodenal development in chicken embryos, duodena from stage 42 White Leghorn (strain Hyline 934F)Gallus gallusembryos were cultured, cut into quarter segments and slit open on grids. L‐T4was added to McCoy's 5A medium to concentrations of 14 ng/ml or 14 ng/100 ml. To control for possible physicochemical effects, D‐T4was added to other media in the same concentrations, and saline vehicle was added to control media. Bovine serum albumin (BSA) was added to a duplicate set of cultures (0.2% w/vol) as a nutritive supplement. After 48 h alkaline phosphatase (E.C. 3.1.3.1) specific activity was significantly elevated (p<0.05) in segments cultured with 14 ng L‐T4/100 ml (non‐BSA) compared to saline control cultures. With 14 ng L‐T4/ml (BSA) phosphatase activity had increased significantly compared to segments treated with 14 ng L‐T4/100 ml (BSA), while those cultured with D‐T4(BSA) had significantly lower activities than all other BSA‐treated groups including controls. Total protein content was significantly elevated in all D‐T4treated segments, both non‐BSA and BSA‐treated, compared to protein values of all other treatment groups. Following 48 h of culture the fine structure of epithelial mucosal cells usually showed condensed cytoplasm, while goblet cells were well developed, structural features appearing in all segments regardless of treatment. The responses after treatment further support a direct role for T4in

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1982.tb00781.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractCentral nerve terminals have been examined for ultrastructural signs of release of neurochemical mediators in the annelidsNereis diversicolor, Harmothoe imbricataandLumbricus terrestris.Two categories of presumptive secretory inclusions are readily distinguished. Exocytosis of ‘storage granules’ is widespread in the neuropile, and involves probable peptidergic terminals as well as more conventional terminals. Plasma membranes at such sites of release are apparently unmodified. In contrast, ‘synaptic vesicles’ are aggregated adjacent to membrane thickenings and specialized clefts, and signs of their fusion with the presynaptic membranes have been observed rarely. The presence of coated pits surmounting omega profiles involving storage granules may indicate that membrane is retrieved in the form of microvesicles from the site of exocytosis. Coated pits associated with synapses have only been observed in areas of membrane adjacent to presumed sites of vesicle exocytosis. The incidence of dual sites of release, often relating to individual terminals, may be indicative of the segregated storage and independent secretion of distinct active principles. Materials released by granule exocytosis may have the role of neuromod

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1982.tb00782.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractThe prolactin (PRL) cells of the pituitary are less active in seawater (SW)‐adapted eels than in freshwater (FW) ones. The kinetics of their response during adaptation to SW or readaptation to FW was investigated. Morphometric studies show that transfer into SW induces a rapid nuclear atrophy, and a reduction of the cell height and of the amount of cytoplasmic granules. These parameters still continue to decrease slowly for one month, becoming then fairly stable. Readaptation to FW stimulates PRL cells after 2 to 10 days. After one or two months, the cells are similar to those of eels kept in FW. The responses of PRL cells appear to be slower in the eel than in Cyprinodonts, which need PRL to live in FW. A complete adaptation to both environments requires one month at least inAnguill

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1982.tb00783.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractThe functional morphology of the olfactory organ inSpinachia spinachia(L.), which has only a single nare, was studied by light microscopy, scanning electron microscopy, and experimental investigations. It was shown that only the incoming water passes over the olfactory epithelium. The device for ventilating this olfactory organ is an accessory ventilation sac activated by respiratory pressure changes in the buccal cavity. This one‐way water current over the olfactory epithelium in a monotrematous olfactory organ was found to be possible because of the morphology of the olfactory organ combined with movements of the lateral wall of the olfactory organ and the nasal tube during respiration. The olfactory epithelium is divided into irregular islets. Both ciliated receptor cells and microvillous receptor cells are presen

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1982.tb00784.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY