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PubMed1985

[Hormone-producing (paracrine) cells in the human labyrinth].

Presence of immunoreactive somatostatin in the covering epithelial cells of the spiral prominence was demonstrated by immunohistochemical methods. The concentration of somatostatin increases from the basal turn to the apical turn of the cochlea. Ultrastructural investigations of these cells reveal secretory granules with a diameter of 250-350 nm. The findings promote the existence of a local paracrine system of the inner ear.

Adolescent↗
PubMedDate not supplied

[Functional relationships between the horizontal and vertical anterior semicircular canals in the labyrinth of the frog (Rana esculenta L.)].

We have studied the vestibular postrotatory reactions (reactions elicited by the stimulation of the horizontal semicircular canals) in the frog blinded by section of optic nerves, before and after section of the ampullary nerves of the vertical anterior semicircular canals (VAC). 90 frogs have been studied. In 30 frogs the ampullary nerves of the two VAC have been cut; in 60 animals either the ampullary nerve of the right VAC or of the left VAC has been cut. Both after section of the ampullary nerves of the two VAC and after section of the ampullary nerve of one VAC, the postrotatory reactions were decreased in about the half of the animals. The decrease of the postrotatory reactions is not due to a lesion of the ampullary nerves of the horizontal semicircular canals and it may be explained by the existence of functional connections between the VAC and the horizontal canal.

Animals↗
PubMed1986

[An ultrastructural study of the localization of alkaline phosphatase and Na-K ATPase in the labyrinth from the IUGR rat].

To elucidate the pathogenesis of intrauterine growth retardation (IUGR), the ischemic placentae produced by uterine artery and vein ligation were morphologically and histochemically investigated in rats. In the ischemic condition, fetal growth was remarkably retarded. The labyrinthi were atrophic and trophoblasts were degenerated ultrastructurally in association with mitochondrial swelling, increased microvesicles, dense bodies and fibrin deposition in the dilated intercellular spaces. Alkaline phosphatase and Na-K ATPase were localized on the plasma membrane in control rats. Na-K ATPase activity was observed in the basal side of cytotrophoblasts. However, the enzyme activities were decreased in the ischemic condition. The reaction products of horseradish peroxidase were present in the dilated intercellular spaces and increased cytoplasmic vesicles. These results suggest that in the ischemic condition, IUGR might be induced by the plasma membrane dysfunction following decreased enzyme activities and irregular distribution of horseradish peroxidase.

Alkaline Phosphatase↗
PubMed1986

[Paradoxical transitory facilitation of performance in the Hebb-Williams labyrinth after lesion of the cingulate cortex in mice].

The effects of lesions of the anterior (Ant) or posterior (Post) regions of the cingulate cortex were tested using the closed-field maze tests of Hebb-Williams. Subjects were male BALB/c mice which had received restricted bilateral electrolytic lesions of the Ant or Post cingulate cortex. Their performances in acquisition or retention were compared to those of sham operated mice at different time intervals after the lesion. In a first series of experiments, naive animals were lesioned. The effects of lesions on acquisition were then tested at different time intervals (up to 45 days) after surgery. In a second series of experiments, the animals were lesioned only after prior complete acquisition of the maze tests and tested in a retention paradigm. The results show a differential effect of Ant versus Post cingulate lesions. Ant lesions had no significant effects whereas Post lesions induced a facilitation of performance at time intervals between 19 and 33 days (acquisition paradigm) or 11 and 25 days (retention paradigm). Conversely a reversal (impairment) of the effect was observed when Post animals were tested 28 days (acquisition) or 48 days (retention) after surgery. Taking into consideration the changing nature of the behavioral paradigm used, we suggest that the paradoxical and transitory facilitatory effects of the Post cingulate lesions may indicate that lesioned mice exhibited a greater degree of adaptability in each new learning situation. However, we can also postulate that these facilitatory effects resulted from a difficulty of lesioned mice in addressing long-term memory stores. This would therefore paradoxically protect them from interference generated by the high degree of familiarity in the behavioural testing apparatus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗