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Biomedical subjects

D Ganchrow

Publications and source records attributed to D Ganchrow.

32 records · Page 2Linked to original sources
PubMed1985

Number and distribution of taste buds in the oral cavity of hatchling chicks.

The location and number of taste buds were mapped in palatal epithelia of one-day old chicks and bud widths measured. Bud counts additionally were recorded for the tongue, and floor of the lower beak. An average of 316 taste buds was observed in the oral cavity of which 69%, 29% and 2% were distributed across oral epithelium in the upper beak (palate), lower beak and posteroventrolateral region of the anterior tongue, respectively. In each oral region, salivary gland ducts lying adjacent as well as gland ductules penetrating through the buds were prevalent. This relation may provide the bio-fluid milieu for receptor stimulation during feeding. Widths of palatal buds were bimodally distributed, peaking at diameters between 40-49 and 60-69 microns. The taste bud-rich oral epithelium in these one-day old chicks is consonant with their precocial nature. The topographic distribution of taste buds appears to be in register with those regions of epithelium contacted by food which is transported anteroposteriorly through the oral cavity by the chicken's prehensile tongue.

Age Factors↗
PubMed1983

Projections of nucleus caudalis and spinal cord to brainstem and diencephalon in the hedgehog (Erinaceus europaeus and Paraechinus aethiopicus): a degeneration study.

In the light of hypotheses related to the evolution of pain-carrying systems in mammals, terminal projection fields in brainstem and diencephalon of efferents of nucleus caudalis (NC) of the spinal trigeminal complex and spinal cord were determined in hedgehog by using Nauta-Gygax and Fink-Heimer silver techniques for degeneration. Unilateral NC lesions resulted in medullary degeneration in the ventral portion of NC contralaterally and bilaterally in cuneate nucleus (CU) and reticular formation. Pontine degeneration was noted ipsilaterally in medial (PBM) and lateral (PBL) parabrachial, facial motor (VII), and interpolar, oral, and main sensory trigeminal nuclei; degeneration in reticular formation was bilateral. Midbrain degeneration was seen bilaterally in caudal superior colliculus (SC), inferior colliculus (IC), periaqueductal gray, and tegmentum. In thalamus, projections to ventroposterior nucleus (VP) were contralateral and concentrated in a crescent extending along the lateral one-third-to-one-half and ventral border of the nucleus. Bilateral degeneration fields were noted in a dorsomedial sector of the "ventral nuclear field," posterior complex (PO), and mediodorsal nucleus (MD), the degeneration always heavier contralaterally in these nuclei. Sparse degeneration was noted in the medial most portions of the medial geniculate nuclei bordering PO and VP. In rostral diencephalon, bilateral degeneration was traced from the inferior thalamic peduncle to the lateral hypothalamic area (LH). Unilateral spinal cord lesions made between C7 and T1 vertebrae resulted in medullary degeneration in NC contralaterally, ipsilaterally in CU and lateral cuneate nucleus, and bilaterally in gracile nucleus, inferior olivary complex, and reticular formation. Pontine degeneration was limited to ipsilateral PBL and bilaterally to VII. Midbrain degeneration was found bilaterally in IC, SC, nucleus sagulum, and tegmentum; a minor projection was noted in interpeduncular nucleus. In thalamus, projections were confined to ipsilateral PO and zona incerta. In rostral diencephalon bilateral fields were noted in LH. NC terminations in PO and VP parallel results of research in hedgehogs on thalamic projections of the dorsal column nuclei (Jane and Schroeder, '71), and particularly the location in VP of most cells responsive to stimulation of the face (Erickson et al., '67). This suggests that somatic input from NC, some of which may be pain-specific, reaches thalamic areas, a portion of whose neurons are characterized as polymodal and at least partially convergent for somatotopy. These results are consistent with the thesis that specific sensory thalamic nuclei evolved from a diffuse sensory region. Response properties of neurons in the dorsomedial portion of the ventral nuclear field, an area which are also received NC efferents, are not known. Last, NC projections to MD and LH implicate the role of "limbic" aspects of nociception.

Animals↗
PubMed1981

Projections of caudal fasciculus gracilis to nucleus gracilis and other medullary structures, and Clarke's nucleus in the rat.

The extent of the projection of fasciculus gracilis from low thoracic (T12--13) spinal cord, to nucleus gracilis (NG) was studied by the Nauta--Gygax method in the rat in order to: (1) help define projection fields of fasciculus gracilis hindlimb and tail afferents along the longitudinal extent of NG; and (2) broaden the comparative data on the projection of the lower body to NG via fasciculus gracilis, already known in cat and monkey. Results showed that: (1) degenerated fasciculus gracilis axons are situated mainly dorsal to the corticospinal fibers, in the dorsal funiculus; (2) terminal projection fields were located at all levels of ipsilateral NG--caudal to the obex, terminal debris was confined to the medial two-thirds of NG--rostrad of the obex, in oral NG, degeneration was of finer caliber and projection fields more diffuse; and (3) ipsilateral degeneration was also seen at the level of a portion of Clarke's nucleus, and, in commissural and lateral cuneate nuclei and medial reticular formation in medulla.

Afferent Pathways↗
PubMed1981

Bouton renewal patterns in rat hindlimb cortex after thoracic dorsal funicular lesions.

The transneuronal effect of bilateral, dorsal funicular lesions (T 12) on the frequency of boutons on cells in layer IV of hindlimb cortex was studied. Adult rats were utilized 1, 2, 3, 7, 14, 30, 45, 60, 90, or 120 days postoperative (DPO), and tissue was processed for the light microscopic visualization of silver-impregnated boutons (Rasmussen method). Bouton counts were taken on soma, or along 5- and 10-micrometers segments or proximal dendrite branching from soma. The soma diameter also was measured on those neurons chosen for bouton counts on the circumference of the soma. Statistically significant, increased afferentation on soma and proximal dendrite occurred during the first postlesion week relative to longer survival times; bouton counts on the proximal dendrite showed a trend (not statistically significant) toward increases above normal. These data mirror similar, consistent increases in bouton counts reported in thalamic ventroposterolateral nucleus of these same cases. At 14 DPO, bouton counts on the soma decreased below normal (P less than 0.005) and, except at 60 DPO, remained so through 120 DPO (P less than 0.025). Bouton counts on the proximal dendrite also decreased below normal at 14 DPO (P less than 0.005), thereafter exhibiting either periodic (along 5-micrometers) or extended (along 10-micrometers) periods in significant decreases from normal. Correlations in lesioned cases between the number of boutons on the soma and either bouton counts on proximal dendrite or soma diameter were positive and statistically significant (P less than 0.005 in all correlations). Possible anterograde (via the dorsal column-medial lemniscal system) and/or retrograde (via the corticospinal tract) transneuronal mediation of these effects in hindlimb cortex is discussed.

Animals↗
PubMed1979

Possible evidence for secondary degeneration of central nervous system in the pathogenesis of anencephaly and brain dysraphia. A study in young human fetuses.

In an attempt to help elucidate pathogenetically those human cases exemplifying secondary degeneration of the neural tube causing brain dysraphia, macroscopic and histologic observations of two young human fetuses are described. A nine-week-old anencephalic fetus exhibited an absence of spinal cord (amyelia) with retention of neural crest derivatives (dorsal root ganglion cells and thusir processes, and sympathetic ganglia) implying the presence of a neural tube in early gestation. The second, ten-week-old exencephalic case exhibited restricted brain hemorrhage and necrosis of the telencephalon and brain stem amongst otherwise normal brain and spinal cord tissue. These two young fetal cases may represent examples of a previously normal neural tube which has undergone degeneration at a stage where neural crest has already undergone differentiation, and thus distinguishes them from cases of complete dysraphism which probably results from primary degeneration during neurulation.

Anencephaly↗
PubMedDate not supplied

Taste quality and intensity: lessons from the Morrison technique.

The nontoxic and nonshock Morrison operant technique was used to evaluate taste quality in rat and marmoset: response to a tastant test solution in pursuit of a pellet reward was dependent on making a choice between two bars that had been linked in discrimination training to qualitatively different stimulus pairs (NaCl versus either HCl, QHCl, or NH(4)Cl). The percentage distribution of bar-press responses to test stimuli showed: (1) stability of quality across 0.069-0.3 M NaCl, 0.003-0.1 M HCl, and 0.0001-0.003 M QHCl; (2) for LiCl, a quality change consistent with human reports of a "sour" to "salty" shift; (3) a suggestion that the "salty-like" quality of NH(4)Cl and NaCl are not perceptually equivalent; (4) NaNO(3) shares NaCl-like, QHCl-like, and NH(4)Cl-like components; (5) CaCl(2), KCl, and MgCl(2) share QHCl-like and NH(4)Cl-like components; and (6) responses to HCl and QHCl were not hedonically driven in the rat. Comparison of rank order correlations of single-unit firing rates to the distribution of bar-press responses for the same test stimulus concentration revealed that (7) no single level of the gustatory pathway exclusively accounts for the operant response distribution pattern to either simple or complex tastants, and (8) discriminations between tastants, one of which may be qualitatively complex, are not necessarily mediated only at levels proximal to the solitary nucleus. Thus, the Morrison discrimination technique effectively yields statements about gustatory quality without use of negative reinforcers and largely uninfluenced by tastant hedonics.

Animals↗