摘要:

AbstractThe ultrastructure of the cystid ofCrisia eburneahas been studied. The cystid wall comprises an outer periostracum, a calcified layer and one inner cell layer, the ectoderm. The membranous sac, which consists of an outer basement membrane, a series of very thin annular muscle cells and an inner layer of epithelial cells, is interpreted as the detached mesoderm of the cystid wall. Accordingly, the atrial sphincter and the generally eight branched, longitudinal muscle cells connecting the terminal membrane and the membranous sac are interpreted as ectoderm. The membranous sac is attached to the cystid wall with two lateral ligaments and at four abfrontal areas: 1) a wide distal area, 2) an area at the origin of the retractor muscles, 3) a small area between 1 and 2, and 4) a small basal area at the origin of a pair of small muscle cells attached to the lowermost part of the caecum.We infer that the protrusion of the polypide is caused by a sequential contraction of the annular muscle cells of the membranous sac, starting basally and aided by the contraction of the longitudinal ectodermal muscle cells.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1979.tb00599.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractThe angioarchitecture of the toad's mesencephalon is studied by scanning electron microscopy of vascular corrosion casts. The arterial supply is performed by the superior mesencephalic artery and by an artery arising from the ramus posterior of the arteria carotis cerebralis just in front of the retroin‐fundibular communicating artery. The venous drainage is exerted by the vena diencephalica, the vena lateralis mesencephalis and by anterior and posterior branches of the encephaloposthypophysial portal vein. Characteristics of the mesencephalic angioarchitecture are the centrifugal direction of the blood flow, the intensive capillarization, and the formation of vascular meshworks in the region of the stratum griseum periventriculare tecti and of the stratum griseum superficiale tect

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1979.tb00600.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractIn the brains of the males the amount of stained secretory material was nearly constant during the last four instars. In the females a decrease in this neurosecretory product in the last nymphal and subimaginal stage could be observed, followed by an increase in the imagines. In the final nymphal stage four types of neurosecretory cells (nsc) were found in the medial protocerebral cell group, showing differences in shape, size, and the contents of the cytoplasm, especially of the secretory granules. In addition to the medial nsc, some cells in the frontal part of the brain and in the deutocerebrum are described. They contain electron‐opaque granules and probably have a neurosecretory function. The secretory product of the medial nsc is transported along the axons of the nervus corporis cardiaci 1 (ncc1), an unpaired nerve tract on the ventral side of the brain. Leaving the brain the ncc1 immediately enters the corpus cardiacum. Connections between secretory granules and neurotubuli point to an important role for the neurotubuli in the transport of secretory materia

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1979.tb00601.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractSagittal sections from pituitaries of winter and spring fish were stained with a number of methods including alcian blue‐PAS‐orange G, Herlant's tetrachrome, Luxol fast blue‐PAS‐orange G and lead haematoxylin. By these methods seven different endocrine cell types were readily demonstrated in the adenohypophysis. In the rostral pars distalis (RPD), there were conspicuous vacuoles (intra‐ and possibly extracellular) in the prolactin cell zone of all animals. The ACTH cells in the RPD were very numerous. In the proximal pars distalis (PPD), the growth hormone cells were arranged in coiling bands that were predominantly dorsal and juxtaposed to neurohypophysis. Two types of basophils were readily distinguished: both were predominantly ventral in the proximal pars distalis, though the type I basophil also formed a constant group in the dorsal region of the pituitary, between the PPD and the RPD. The pars intermedia contained two cell types — a lead haematoxylin‐positive cell and a PAS‐positive cell. The pituitary morphology is compared with that of

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1979.tb00602.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractThe early upstream migrants of the lamprey,Geotria australis, were occasionally found dead in the field and suffered a very heavy mortality when held in the laboratory. The clinical signs exhibited by dying animals included the production of massive amounts of mucus, petechial haemorrhage of the skin and fins, and both haemorrhage and oedema around the eyes. Necropsy also revealed haemorrhage and oedema in various internal structures and in one case thrombosis and degeneration of blood vessels in the gill. The disease was attributed to infection withAeromonas hydrophilaandPseudomonas fluorescenswhich were cultured from the organs of diseased animals. No signs of this disease occurred when the aquaria water was treated with chlortetracycline immediately after the introduction of each new batch of animals.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1979.tb00603.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1979.tb00604.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY