Biomedical subjects

N A Locket

Publications and source records attributed to N A Locket.

14 recordsLinked to original sources

PubMed1995

The inner ear of the echidna Tachyglossus aculeatus: the vestibular sensory organs.

The monotremes, comprising the echidnas and platypus, have more sensory organs in the inner ear than do other mammals. In addition to the organs usually seen in the mammalian inner ear, they have a lagenar macula, a sense organ found in all non-mammalian vertebrates. In the echidna Tachyglossus aculeatus, this macula consists of a narrow sensory strip at the end of the cochlea. All vestibular sensory organs are populated by two types of sensory cells, cylindrical bouton-innervated hair cells and more or less regular bottle-shaped calyceal-innervated hair cells. The two types are mixed in all vestibular organs, as in placental mammals, and their arrangement in the maculae in particular is very unlike that in reptiles. The sensory epithelia are very large relative to the size of the animals. The utricular macula contains more sensory cells than found in any other amniote so far examined.

Animals↗

PubMed1992

Problems of deep foveas.

Deep or convexiclivate foveas occur in some birds, including raptors, some lizards and certain deep-sea fishes. Theories on their function are reviewed. Common to raptor and deep-sea fish foveas is a radial fibre lining, dark staining so probably optically dense, adjacent to the less refractile vitreous. The foveal curvatures and size are remarkably similar in a wide taxonomic and size range of birds and fishes. Ray plotting through traced foveal outlines suggests that sharp images will be formed beneath the centre and shoulders, with the centre image enlarged enough to account for the high acuity of raptors. Deep foveas will also exaggerate eccentricity of off-centre images of a point source, such as deep-sea fishes may meet. Despite similarities in foveal shape, the receptors differ widely between species. Raptors, and notosudid fishes, have short cones. Searsid fishes have long single rods. Howella and Bajacalifornia have multiple bank rods, more in the fovea than the periphery. Those of Howella are shown to be multiple inner-outer segment complexes rather than interrupted single rods. Implications of foveal and receptor features are discussed.

Animals↗

PubMed1985

Persistent trigeminal artery: an anatomical study.

A detailed anatomical study of three persistent trigeminal arteries (PTA) is presented. In two cadavers the PTA linked the carotid and basilar systems by traversing the cavernous sinus and lying between the posterior clinoid process and the sensory root of the trigeminal nerve. In the third cadaver the PTA pierced the dorsum sellae and lay in the floor of the pituitary fossa. The potential clinical significance of the course and the possible pattern of blood flow in the vessels is discussed in the light of some recent clinical observations.

Aged↗

PubMed1980

Some advances in coelacanth biology.

Participants in the British-French-American Expedition to the Comoro Islands in 1972 were able to observe a living coelacanth and to obtain fresh tissue from two specimens, which were processed in the field for subsequent research. This work, by many people in several countries, still continues, and this lecture gives a condensed account of some of the investigations so far published and in progress. Separate accounts of the French contributions, by J. Anthony, of the chemistry of the body fluids, by R. W. Griffith, and of the respiration, by G. M. Hughes, are being published concurrently, the four papers being complementary to each other. A bibliography on Latimeria is included.

Animals↗

PubMed1977