摘要:

AbstractWhen 6‐OH dopamine (6‐OHDA) was injected into the body cavity of eels (Anguilla anguillaL.), which had been kept on a light background with continuous artificial illumination or a natural day‐night regime in May and June, evident but heterogeneous chromatic reactions were induced. After peripheral drug effects during the first 6 hours, the eels became darker for 2 or 3 days, whereupon the melanophore index (MI), in most cases, decreased. Darkening was accompanied by significant nuclear hypertrophy and moderate degranulation of the MSH (melanophore‐stimulating hormone) cells. Probably only some of the adrenergic nerves in the neural lobe were affected. The blood supply to the brain was decreased for several days after each injection. The results support the assumption that in the eel catecholamines released from nerve endings in the neural lobe inhibit the release of MSH from intermedia cells by their own action as an inhibiting factor, or by affecting an MIF (MSH‐release inhibiting factor) and/or an MRF (MSH‐releas

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1973.tb00459.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractThe formation of double cones in the retina of fry ofPerca fluviatilishas been investigated by light and electron microscopy. The retina of newly hatched fry is provided with single cones and rods, single cones being the predominant receptor type. Double cones are seen for the first time 22 days after hatching. Mitoses are observed in the periphery of the retina, but are also seen in more central parts of the retina containing differentiated receptors and a cone mosaic. The fate of the cells resulting from the centrally located mitoses is not known. No signs of longitudinal fission of differentiated single cones are seen. It is suggested that double cones in the retina of perch fry arise by fusion of single cones which associate closely and develop subsurface cisterns coextensive with the region of intimate contact in the ellipsoid.During the first few weeks after hatching, there is a gradual shift in arrangement of the cones. In the newly hatched fry, the single cones are arranged in rows. When double cones are first seen, square‐pattern units appear, built up from four double cones and a single con

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1973.tb00460.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractThe vascularization of the pituitary region inAcipenser ruthenusL. (Chondrostei) is described. The adenohypophysis has no direct arterial supply but is fed exclusively by a pituitary portal system supplied through a pair of infundibular arteries. Distinct portal vessels connect the lateral part of the primary plexus of the neurohaemal area (the median eminence) with the secondary plexus of the pituitary gland. The primary plexus enters the pars distalis paramedially, apparently without the formation of distinct portal vessels. The neuro‐intermediate lobe receives its blood supply exclusively from the primary plexus. The plexus intermedius gives off capillaries to the parenchyma of the intermediate lobe (an intermediate lobe sinus system). The saccus vasculosus receives (1) a “direct” supply,i.e.branches originating directly from the cerebral arteries and (2) an “indirect” supply,i.e.capillaries from the primary plexus. The pars distalis is drained into an unpaired ventral hypophysial vein, while a dorsal hypophysial vein, also unpaired, drains the plexus intermedius. These two veins join to form the unpaired hypophysial vein. The findings are discussed from comparative and functional v

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1973.tb00461.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractThe apical part of the olfactory epithelium inMyxine glutinosawas investigated by optical and electron microscopy. This part of the epithelium consists of supporting cells and two types of olfactory receptor cells,i.e., ciliated receptor cells and microvillous receptor cells. The olfactory cilia have a 9 + 0 pattern of the microtubules, occasionally with one pair of the doublets dislocated towards the center of the cilium. Giant cilia were observed. The supporting cells bear microvilli and are rich in tonofilaments. The supporting cells also have a secretory function, their secretion consisting mainly of acid mucopolysaccharides. An asymmetrical type of desmosome was found between the olfactory receptor cells and the supporting cells.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1973.tb00462.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractIn the hagfishMyxine glutinosanerve fiber bundles in the lamina propria of the olfactory lamellae run dorsally and collect to form dorsal nerves which posteriorly enter the olfactory bulb. The nerve fibers in the lamina propria and in the transitional regions between the lamina propria of each lamella and the dorsal nerves display two different appearances: 1.Small fibers(olfactory axons) range approximately between 85 and 165 nm in diameter; the cytoplasm is more electron dense than that of large fibers; one or a few microtubuli are frequently seen in the cytoplasm, whereas mitochondria are seldom observed; 2.Large fibersrange approximately between 500 and 1200 nm in diameter; the cytoplasm is electron translucent and mitochondria occur frequently. Nerve fibers in the dorsal nerves have a diameter of 100 to 500 nm and within a nerve bundle they are grouped infasciculiwith an estimated fiber density of 16/μm2. Figers with diameter exceeding 500 nm are very seldom seen in the dorsal nerves.The small fibers are with great certainty olfactory receptor cell axons, since their size, fine structure and organization infasciculiis entirely similar to that described in other species. The structure and distribution of large nerve fibers are discussed with regard to the possibility that they either are efferent fibers which constitute an extrinsic innervation of the olfactory epithelium or are the axons of olfactory receptor cells

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1973.tb00463.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY