摘要:

AbstractScanning electron microscopy and light microscopy demonstrate that the mature thread cells inEptatretus deaniandMyxine glutinosaconsist of a single, coiled thread up to 10 cm long. Mature thread cells apparently loose the cell membrane within the slime gland before expulsion. Thus the old idea that rupture of the cell membrane causes the uncoiling in sea water is no longer tenable. If the thread cells are transferred without additional fluid to a microscope slide, no uncoiling occurs until sea water or distilled water is added when the process occurs rapidly; however, in double strength sea water uncoiling is slowed down. In tetrahydrofuran or glycerin there is no uncoiling in 100 % or 50 % solutions; however in 5 % solutions uncoiling occurs slowly. Thus the availability of adequate amounts of water seems to be necessary for uncoiling. Presumably, water acts directly on the thread, causing the organelle to straighten and thus uncoil. The defensive value of the slime production is discussed.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1981.tb00623.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractCiliated cells in the rostral epidermis of amphioxus have been serial sectioned and examined in the electron microscope. The cells have a basal axonic process, which can be traced to the subcutaneous nepve‐bundles, and hence these cells are primary sensory cells. Apically only the cilium, which takes its origin from an invagination, and a surrounding corolla of microvilli are exposed to the surface. Cross‐striated filament bundles closely associate with a basal body and accessory centriole. One such bundle continues into the central part of the cell, while another bundle is attached at the lateral membrane. Between adjoining cells there are apical zonulae adhaerentes, and also poorly developed septate junctions. In addition, a third cell junction is described. Rod‐like structures in the surface interdigitations are shown to be continuous with a peripheral layer of microfilaments. The choanocyte‐like appearance of the ciliated cells and their resemblance to similar cells in various invertebrates are di

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1981.tb00624.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractVascular casting and dissection of fresh specimens had been used to investigate the arrangement of vessels before and after the gills in the head region of the eel. Arterial and venous morphology was found to be as reported in previous works, but the presence in the eel of a venous system that does not confom to the generalised teleost plan necessitated the use of a non‐standard nomenclature. The gills are the site of the connection of the arterial system with a second vascular system and it is suggested that this system should be termed the veno‐lymphatic system. The veno‐lymphatic system connects dorsally to the systemic lymphatic system and so to the internal jugular vein. Ventrally the veno‐lymphatic vessels from the first three gill arches are collected into a connective tissue sheath around the ventral aorta. The sheath is connected to a veno‐lymphatic sinus posterior to it which also collects the veno‐lymphatic of the fourth gill arch. This sinus then drains into the external jugular vein which at this point is the fusion of the left and right branches. These later separate and each branch contains a valve preventing flow towards the ventral aortic sheath. It is proposed that because of the form of this ventral route for veno‐lymphatic drainage, and the ease and completeness of filling of this route compared with the dorsal route, that the ventral veno‐lymphatic system is probably the primary route of drainage of veno‐lymphatic outfl

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1981.tb00625.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractThe inner ear of the caecilianIchthyophis glutinosusis briefly described. An analysis of the fine structure of the utricular macula show the presence of several varieties of hair cells. At least one type seems to be degenerating, another developing. A slow hair cell turnover is proposed. The number of afferent nerve endings in contact with a few hair cells were found to be 6–13 as reconstructed from electron microscopical serial sectionin

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1981.tb00626.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractA histochemical study was made of the distribution of catecholamines and cholinesterases in two autonomic ganglia closely associated with the swimbladder of the Atlantic cod,Gadus morhua. The “swimbladder nerve ganglion” comprised large (40 μm) neurones, the majority of which are positive for both catecholamines and acetylcholinesterase. It is argued that these neurones are mainly adrenergic postganglionic elements of sympathetic pathways which pass through the vago‐sympathetic trunk. The “gas gland ganglion” comprised small (20 μm) neurones, positive for acetylcholinesterase but showing no catecholamine reaction. It is argued that these neurones are cholinergic postganglionic elements of the parasympathetic vagal innervation of gas

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1981.tb00627.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractLight and electron microscopic studies showed that the oral gland cells have two quite different zones. Medially, the basal zone is in contact with body fluids and the endostyle. Its strongly pyroninophile cytoplasm contains the extremely digitated nucleus and numerous small mitochondria. Laterally, the apical zone contacts the epidermis and it may also send a process between epidermal cells and deliver cell fragments into the primordium of the new house. This cell zone contains numerous membranes. It is concluded that the oral gland cells are light producing glands and that the membrane‐rich cell fragments which are incorporated into the house wall are the source of the bioluminiscence which has been reported from empty houses. The ontogenetically related subchordal cells have a similar structure and it is possible that also these cells are light producer

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1981.tb00628.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY