John R. Cotter

Visual and Nonvisual Units Recorded from the Optic Tectum of Gallus domesticus

Units recorded from the optic tectum of Gallus domesticus were tested for responses to visual, auditory and somesthetic and stimuli. Units recorded from the superficial tectal layers (stratum opticum, stratum griseum et fibrosum superficiale) responded only to visual stimuli. On the basis of the units responsiveness to the directionality of a moving visual stimulus, three unit types referred to as pandirectional, unidirectional, and multidirectional units were identified. In the deeper layers (stratum griseum centrale, stratum album centrale) unimodal and bimodal units were encountered. These units responded to visual, auditory, and/or somesthetic stimuli. These results indicate that the tectal cortex of Gallus domesticus is subdivided into two functional divisions: the superficial layers which correlate visual information and the deep layers which correlate visual and nonvisual information.

Uncrossed retinal projections to the accessory optic nuclei in rabbits and cats

SummaryRetinal projections to the accessory optic nuclei of rabbits and cats were demonstrated with standard autoradiographic techniques following intraocular injections of [35S]methionine and [3H]proline.In the pigmented rabbit, albino rabbit, normally pigmented domestic cat and Siamese cat the medial, lateral and dorsal terminal nuclei (MTN, LTN, and DTN, respectively) of the accessory optic system were densely labelled on the side contralateral to the injected eye. An ipsilateral projection, while clearly present in all but the Siamese cat, varied in the number of nuclei involved. In the albino rabbit, the ipsilateral projection ended in the MTN, while in the pigmented rabbit, it ended in the MTN, LTN and DTN, and in the normally pigmented domestic cat it ended in the MTN and LTN.These results indicate that the accessory optic system in rabbits and cats is more extensive than previously reported and that differences exist in the accessory optic system which may be related to genetic differences in normally pigmented and hypopigmented animals.

Attenuation of contraction-induced skeletal muscle injury by bromelain.

The proteolytic enzyme, bromelain, reportedly has therapeutic effects in the treatment of inflammation and soft tissue injuries. We tested the hypothesis that bromelain attenuates skeletal muscle injury induced by lengthening contractions. The left extensor digitorum longus (EDL) muscle of anesthetized hamsters was injured using a motorized foot pedal which repeatedly flexed/extended the foot through a range of 125 degrees. The EDL muscle was electrically stimulated for 400 ms during plantarflexion. Animals were assigned randomly to either a 0-d group (evaluated 3-h post-injury) or to untreated (UT) or bromelain-treated (T) groups, evaluated 3, 7, or 14 d post-injury. Following injury, T received 5 mg.kg-1 b.w. of bromelain, twice daily. Maximum isometric tetanic force (Po) was measured in vitro, then muscles were fixed, sectioned, and examined for evidence of fiber damage. The Po of injured muscles from T were higher than Po of injured muscles from UT at 3 (18.7 +/- 0.4 vs 16.5 +/- N.cm-2 and 14 d (20.5 +/- 0.6 vs 18.2 +/- 0.6 N.cm-2) (P less than 0.05), but not 7 d (19.5 +/-0.7 vs 17.7 +/- 0.8 N.cm-2). The Po of UT injured muscles were significantly lower than Po of contralateral control muscles at all time periods. Po of injured muscles from T were lower than Po from control muscles at 3 and 7 d (P less than 0.05), but not 14 d. The number of intact fibers of 3-d UT injured muscles was lower than the number of intact fibers in control muscles (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Immunocytochemical localization of vasoactive intestinal polypeptide (VIP) in the brain of the little brown bat (Myotis lucifugus)

SummaryVasoactive intestinal polypeptide (VIP)-like immunoreactivity has been examined in the brain of the little brown bat,Myotis lucifugus, using light microscopic immunocytochemistry and the indirect antibody enzyme method of Sternberger. Animals were sacrificed at three different and discrete levels of physiological activity: euthermic, hypothermic and hibernating. The density and distribution of immunoreactive neurons and fibres was compared in the three animal groups with the aid of a computerized image analysis system. Our results were compared with those of previous studies in laboratory species such as the rat and cat.Our study has demonstrated marked changes in the density of VIP-immunoreactive fibres and plexuses in the anterior hypothalamic area which correspond to the physiological state of the animal. In addition we have demonstrated the presence of VIP immunoreactive perikarya in a number of previously unreported locations. These include the paraventricular and periventricular hypothalamic nuclei, the linear raphe nucleus, nucleus interfascicularis, and in neurons embedded in the fibres of the dorsal tegmental decussation.

Endocytosis of cationized ferritin by rat photoreceptors

Endocytosis by rods of the rat retina was studied at the ultrastructural level with cationized ferritin. Endocytosed ferritin was found within all photoreceptor subdivisions except the outer segment. Within the cell, synaptic vesicles, lysosomes and a variety of other membrane-bound organelles including the axonal agranular reticulum contained ferritin. These findings indicate that surface membrane and materials bound to surface membrane are recycled to form synaptic vesicles, that a portion of the captured membrane and extracellular material enters a lysosomal pathway, and that endocytosed materials can be retrogradely transported to the myoid region of the photoreceptor.

VIP-like immunoreactivity in the anterior hypothalamic area of a hibernating bat varies with physiological state.

Vasoactive intestinal polypeptide (VIP)-like immunoreactivity in the anterior hypothalamic area (AHA) was studied in 15 bats which are seasonal hibernators, using the unlabeled antibody enzyme method of Sternberger. Our results showed that the density of immunoreactive fibers and terminal plexuses in the AHA was greatest in euthermic animals and decreased dramatically when body temperature and cardiac rate were depressed and animals entered hibernation.

Histology on the World Wide Web: A digest of resources for students and teachers

Thirty-seven World Wide Web (WWW) sites that are devoted to instruction in histology were compiled and organized into a digest. The sites were located using Netscape and two search engines (Lycos and HotBot). The scope and design of the sites were highly variable and the Web sites could be categorized as electronic manuals, syllabi, atlases, image galleries and quizzes. Those listed in the digest can be used for teaching, learning and reviewing laboratoy histology. To assist instructors and students in identifying those that are most likely to be useful to them, the topics, content and highlights of each were briefly reviewed.

Neuropeptide Y innervation of the cerebellum in the little brown bat (Myotis lucifugus).

Light microscopic immunocytochemistry for neuropeptide Y (NPY) has demonstrated the presence of a diffuse system of NPY-immunoreactive fibers in the cerebellum of Myotis lucifugus. These fibers gain access to the cerebellum by way of the superior cerebellar peduncle, and terminate on Purkinje cell dendrites and on neurons in the granule cell layer. The origin of cerebellar NPY and possible colocalization with norepinephrine are discussed.

Organization of the retinofugal fibers to the dorsal lateral geniculate nucleus of Pteropus giganteus

SummaryThe projection of the retina to the dorsal lateral geniculate nucleus was studied following unilateral enucleations and intraocular injections of tritiated proline in the fruit bat, Pteropus giganteus. Three cell laminae (lamina 1, 2, 3) were identified in Nissl preparations. Input from the two eyes to the laminae was partially overlapping and segregated. At levels where the input was clearly segregated the input from the contralateral eye ended in the outer portions of the three laminae while the input to the laminae from the ipsilateral eye ended along the medial edge of the optic tract (lamina S) and the inner portions of the three laminae. These results indicate that the organization of the projection is similar to that described in other mammals, i.e., the terminals of input fibers from the retina form concealed terminal laminae and they are to some degree segregated to specific terminal zones within laminae.