... and jawless vertebrates are crucial. Cyclostomes – lampreys and hagfishes – are the only extant jawless vertebrates, and diverged from jawed vertebrates (gnathostomes) over 500 million years ago. Previous developmental studies on the cyclostome brain were conducted mainly in lampreys because hagfish embryos...

... areas, the thalamus, the basal ganglia with the dopamine system, and the habenulae. The ambition here is to compare the mammalian forebrain with that of the lamprey representing the oldest now living group of vertebrates, by a review of earlier studies. We show that the lamprey dorsal pallium has...

... and, therefore, homologous between the major vertebrate lineages. One challenge for this hypothesis is that the olfactory bulbs project throughout most of the pallium in the most basal vertebrate lineages (notably lampreys, hagfishes, and lungfishes) but do not project to the putative dorsal pallia in teleosts...

...Manuel A. Pombal; Manuel Megías; Sylvia M. Bardet; Luis Puelles Ten years ago, we published the first detailed prosomeric map of the forebrain in lampreys. In the interim, the prosomeric model has been modified and simplified to better explain numerous data on the expression patterns of regulatory...

...R.J. Martin 47 reticulospinal neurons of the lamprey brain-stem were stained by intracellular injection of Procion yellow, so that their morphology and dendro-architecture could be determined. The vagal, bulbar, Mauthner, isthmic and mesencephalic groups could be distinguished by the shape and size...

...Arthur N. Popper; Becky Hoxter The inner ear of the sea lamprey, Petromyzon marinus, was examined using scanning and transmission electron microscopy. Many of the nonsensory surfaces of the ear chamber are lined by numerous, noninnervated, multiciliated epithelial cells. Each multiciliated...

...Mark Ronan; R. Glenn Northcutt Primary lateralis projections in silver lampreys, Ichthyomyzon unicuspis, and young adult sea lampreys, Petromyzon marinus, were examined utilizing silver impregnation of degenerating fibers and transganglionic transport of horseradish peroxidase. Anterior lateral...

... in the telencephalon and diencephalon. In lampreys, the majority of labeled fibers terminate in the hypothalamus, while in bony fishes the main projection is to periventricular nuclei of the anterior commissure. The course of the nervus terminalis through the dorsomedial telencephalon in lungfishes supports...

...R. Kawasaki; Carl M. Rovainen Feeding behavior was initiated in juvenile and adult lampreys, Ichthyomyzon unicuspis, by attachment to goldfish or by injection of saline extracts of goldfish skin and muscle into the sucker cavity. Feeding was confirmed by the apparent swallowing of fish extract plus...

...Scott N. Currie Larval lampreys (ammocoetes) exhibit a rapid vibration-evoked startle response involving a bilateral activation of musculature along the length of the body. The resulting movement is variable, contingent on the animal's prestimulus posture: lateral curves along the trunk and tail...

...Carl M. Rovainen A basic problem faced by the agnathans in evolution was how to feed and breathe without jaws. Three solutions are represented by lampreys and their ammocoete larvae, reviewed here, and hagfishes. Lampreys feed upon fish with their suckers and breathe in and out of their branchial...

...N.P. Vesselkin; J.-P. Rio; J. Repérant; N.B. Kenigfest; V.O. Adanina In the lamprey Lampetra fluviatilis the centrifugal visual system is well developed. Centrifugal fibers arise from cells of two tegmentomesencephalic nuclei–reticular mesencephalic area and nucleus M5 of Schober – as demonstrated...

...James T. Buchanan An isolated lamprey spinal cord generates rhythmic ventral root bursting that closely resembles swimming activity: ventral roots on opposite sides of the spinal cord burst in alternation, and rostral ventral roots lead caudal ventral roots. This rhythmic activity is induced...

...María del Carmen de Arriba; Manuel A. Pombal Tectal afferents were studied in adult lampreys of three species (Ichthyomyzon unicuspis, Lampetra fluviatilis, and Petromyzon marinus) following unilateral BDA injections into the optic tectum (OT). In the secondary prosencephalon, neurons projecting...

.... The abducens and trochlear nerves of lampreys add further unusual features. The axons of VI neurons in lampreys do not exit ventrally like those of somatomotor neurons, rather they ascend rostrally to exit in close association with the V root, acting more like branchiomotor axons. Likewise, the lateral...

...Adam R. Root; Nathaniel V. Nucci; Jocelyn D. Sanford; Beverly S. Rubin; Vance L. Trudeau; Stacia A. Sower The distribution of lamprey gonadotropin-releasing hormone (GnRH)-I and -III has been extensively characterized by immunocytochemistry in the forebrain of the sea lamprey, Petromyzon marinus...

... of sea lamprey, Petromyzon marinus . In immunocytochemical studies, GABA-containing neurons were detected early in lamprey development, by day 20 post-fertilization. At this time point, one population of GABA-containing neurons was visualized in the hypothalamus and preoptic area, and another population...

...Shaun P. Collin; Ian C. Pottert A description is given of the morphological and ultrastructural characteristics of the eye of Mordacia mordax, one of the two parasitic species of the southern hemisphere lamprey family Mordaciidae. The avascular retina is well-differentiated, containing two ganglion...