Photographs of individually identified humpback whales Megaptera novaeangliae were collected in regions throughout the central and eastern North Pacific during the years 1977 to 1983. A comparison of these photographs revealed extensive movement between seasonal habitats. Whales found wintering near Hawaii traveled to summer feeding regions throughout the coastal waters of Alaska. Whales wintering near Mexico were found in Alaskan feeding regions and near the Farallon Islands off central California. I-lttle exchange was found between the 2 wintering grounds or among the 5 summering grounds studied. Fidelity to a given feeding region was demonstrated by a high proportion of migratory return. Evidence of fidelity to a given wintering ground was less conclusive. The coloration of humpback whale flukes showed a longitudinal cline across the 5 feeding regions. Flukes of whales from the easternmost feeding regions were, on average, darker than those from the westernmost feeding regions. Whales in Hawaii and Mexico were similar in fluke coloration and the average coloration on both wintering grounds was intermediate between the extremes of the feeding regions. We propose that humpback whales in the eastern and central North Pacific form a single 'structured stock' consisting of several geographically-isolated 'feeding herds' which intermingle on 1 or more wintering grounds. Mark-recapture analyses of resightlng data indicate that the Hawaiian wintering congregation is 4 to 6 times larger than the southeastern Alaska feeding herd. Within a structured stock, sets of whales interact with different probabilities in each seasonal habitat. This, in turn, has important implications for the social organization and management of these whales.

To identify rat brainstem nuclei involved in the initial, shortterm response to a change in gravito-inertial force, adult Long-Evans rats were rotated in the horizontal plane for 90 min in complete darkness after they were eccentrically positioned off the axis of rotation (off-axis) causing a centripetal acceleration of 2 g. Neural activation was defined by the brainstem distribution of the c-fos primary response gene protein, Fos, using immunohistochemistry.The Fos labeling in off-axis animals was compared with that of control animals who were rotated on the axis of rotation (on-axis) with no centripetal acceleration, or who were restrained but not rotated. In the off-axis animals there was a significant labeling of neurons: in the inferior, medial, and y-group subnuclei of the vestibular complex; in subnuclei of the inferior olive, especially the dorsomedial cell column; in midbrain nuclei, including the interstitial nucleus of Cajal, nucleus of Darkschewitsch, Edinger-Westphal nucleus, and dorsolateral periaqueductal gray; in autonomic centers including the solitary nucleus, area postrema, and locus coeruleus; and in reticular nuclei including the lateral reticular nucleus and the lateral parabrachial nucleus. Also, there was greater Fos expression in the dorsomedial cell column, the principal inferior olive subnuclei, inferior vestibular nucleus, the dorsolateral central gray, and the locus coeruleus in animals who had their heads restrained compared to animals whose heads were not restrained. As one control, the vestibular neuroepithelium was destroyed by injecting sodium arsanilate into the middle ear, bilaterally. This resulted in a complete lack of Fos labeling in the vestibular nuclei and the inferior olive, and a significant reduction in labeling in other nuclei in the off-axis condition, indicating that these nuclei have a significant labyrinth-sensitive component to their Fos labeling. The data indicate that several novel brainstem regions, including the dorsomedial cell column of the inferior olive and the periaqueductal gray, as well as more traditional brainstem nuclei including vestibular and oculomotor related nuclei, respond to otolith activation during a sustained centripetal acceleration.Received Mar. 2, 1992; revised June 5, 1992; accepted June 12, 1992. We thank Jaw-Hem Lee and Huna Nauven for their sutmortine work in our labs. This work is made possible by a griduate student researchepprogram fellowship and NIH Grants DC01086, NS19208, DC001 10, DE06682, and DA06687.Correspondence should be addressed to Alvin J. Normal coordination of body movement and posture depends upon an accurate spatial reference. The otolith organs of the vestibular labyrinth are sensitive to the direction and magnitude of the earth's gravity and could provide a reference for integrating vestibular, visual, and somatosensory information to help control movement. When a sustained change in the gravitoinertial force occurs (e.g., from a novel linear motion, in a microgravity environment, or as a result of inner ear...

HYPOTHESIS:: Exposure to ciprofloxacin/dexamethasone, but not ofloxacin, prolongs tympanic membrane (TM) healing. BACKGROUND:: Exposure to hydrocortisone has been shown to delay TM wound healing. No published studies have compared the effects of ciprofloxacin/dexamethasone and ofloxacin on TM healing. METHODS:: Noninfected TM perforations were created in 30 rats. The rats were split into three groups, and ciprofloxacin/dexamethasone, ofloxacin, or isotonic sodium chloride solution drops were instilled for 8 days. Tympanic membrane healing was analyzed at specified intervals using photographic documentation verified by a blinded observer. RESULTS:: The isotonic sodium chloride solution control and ofloxacin-exposed TMs healed at similar rates. There was a statistically significant delay in TM healing in the ciprofloxacin-/dexamethasone-exposed TMs by postoperative Day 10. However, all TM perforations were healed by postoperative Day 20. CONCLUSION:: Ciprofloxacin/dexamethasone delays healing of experimental TM perforations, but the brief exposure in this study did not cause persistent perforations.

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