Fine Structures of Utricle of Developing Chick Embryo Exposed to 2G Gravity

Hara, Hirotaka; Sekitani, Toru; Kido, Toshishige; Endo, Shiro; Ikeda, Takuo; Takahashi, Masahiro

doi:10.3109/00016489509121918

Cited by 26 publications

(3 citation statements)

References 6 publications

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“…The size of otoconia is increased in animals subjected to microgravity (Wiederhold et al 1997), while animals born in hypergravity, have smaller otoconia (Krasnov 1991;Lim et al 1974;Sondag et al 1996), thinner utricular membranes (Lim et al 1974) with increased crosssectional areas of epithelial cells (Wubbels et al 2002). In addition, a delayed growth was observed in hamsters (Sondag et al 1996) as in fish and chicks (Anken et al 2001a, b;Hara et al 1995). Under hypergravity, a delay was found in the postnatal development of connections between type I hair cells in the utricles and their afferent calyces (Gaboyard et al 2003), and a slower development of the potassium currents in type II hair cell was reported (Chabbert et al 2003), and poorly developed saccular axons with few or no side branches or synapticlike terminals were found in the medial vestibular nucleus (Bruce 2003), while axonal branches of posterior canal axons differed in rat fetuses that developed in microgravity (Bruce and Fritzsch 1997) suggesting a delay in synaptogenesis in the medial vestibular nuclei.…”

Section: Introductionmentioning

confidence: 92%

Ground-Based Researches on the Effects of Altered Gravity on Mice Development

Jamon

Serradj

2008

Microgravity Sci. Technol.

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This chapter reviews some consequences of the exposure to an altered gravity environment on the development of small mammals. A point is made on the possible existence of several critical periods, and their interactions, in relation with the multiple points of application of the gravity influence on developing organisms, and the need to coordinate the researches on the various structures concerned. The European effort to integrate a multidisciplinary exploration, from the genes expression to the behavioural output, in a topical team is presented, and a new French centrifuge facility for mice is described. A second part reports the preliminary results of a study on the motor performance of ageing (9 months) mice exposed to Hypergravity (2 g), in the new French centrifuge, between the 10th to 31 postnatal day, a key period for motor development in mice. This study shows for the first time that a transient exposure to an hypergravity environment during the period of motor development in the mouse produced an irreversible modification of the motor function.

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Section: Introductionmentioning

confidence: 92%

Ground-Based Researches on the Effects of Altered Gravity on Mice Development

Jamon

Serradj

2008

Microgravity Sci. Technol.

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“…This process was observed in different species including snails (Wiederhold et al, 2003a), aplysia (Pedrozo et al, 1996), fish (Wiederhold et al, 1997; Anken et al, 2001, 2002a,b; Wiederhold et al, 2003a,b), Xenopus (Lychakov and Lavrova, 1985), chicken (Hara et al, 1995), hamsters (Sondag et al, 1996), rats (Lim et al, 1974; Krasnov, 1991). At variance the otoconia of animals exposed to altered gravity at maturity did not show any change (Lim et al, 1974; Ross et al, 1985; Hara et al, 1995; Sondag et al, 1995). Some of these results supported the existence of a critical period during the development of otoliths (Wiederhold et al, 2003a,b).…”

Section: Effects Of Altered Gravity On the Development Of Gravity Senmentioning

confidence: 98%

The development of vestibular system and related functions in mammals: impact of gravity

Jamon

2014

Front. Integr. Neurosci.

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This chapter reviews the knowledge about the adaptation to Earth gravity during the development of mammals. The impact of early exposure to altered gravity is evaluated at the level of the functions related to the vestibular system, including postural control, homeostatic regulation, and spatial memory. The hypothesis of critical periods in the adaptation to gravity is discussed. Demonstrating a critical period requires removing the gravity stimulus during delimited time windows, what is impossible to do on Earth surface. The surgical destruction of the vestibular apparatus, and the use of mice strains with defective graviceptors have provided useful information on the consequences of missing gravity perception, and the possible compensatory mechanisms, but transitory suppression of the stimulus can only be operated during spatial flight. The rare studies on rat pups housed on board of space shuttle significantly contributed to this problem, but the use of hypergravity environment, produced by means of chronic centrifugation, is the only available tool when repeated experiments must be carried out on Earth. Even though hypergravity is sometimes considered as a mirror situation to microgravity, the two situations cannot be confused because a gravitational force is still present. The theoretical considerations that validate the paradigm of hypergravity to evaluate critical periods are discussed. The question of adaption of graviceptor is questioned from an evolutionary point of view. It is possible that graviception is hardwired, because life on Earth has evolved under the constant pressure of gravity. The rapid acquisition of motor programming by precocial mammals in minutes after birth is consistent with this hypothesis, but the slow development of motor skills in altricial species and the plasticity of vestibular perception in adults suggest that gravity experience is required for the tuning of graviceptors. The possible reasons for this dichotomy are discussed.

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“…On the other hand otolith size increased significantly in the developing snail and fish exposed to microgravity (186). Studies in Aplysia (187), Xenopus laevis (188) chicks (189,190), hamsters (191,192) and rats (193) suggest that, after the otolith/otoconia develops, subsequent exposures to either hypergravity or microgravity have little effect on their morphology. However, hamsters exposed to an altered gravitational environment during their development show subtle changes in the otoconia in terms of the relative distribution of the small, medium and large otoconia (192).…”

Section: Vestibular System and Signal Detectionmentioning

confidence: 98%

Brain development, environment and sex: what can we learn from studying graviperception, gravitransduction and the gravireaction of the developing CNS to altered gravity?

Sajdel-Sulkowska

2008

Cerebellum

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As man embarks on space exploration and contemplates space habitation, there is a critical need for basic understanding of the impact of the environmental factors of space, and in particular gravity, on human survival, health, reproduction and development. This review summarizes our present knowledge on the effect of altered gravity on the developing CNS with respect to the response of the developing CNS to altered gravity (gravireaction), the physiological changes associated with altered gravity that could contribute to this effect (gravitransduction), and the possible mechanisms involved in the detection of altered gravity (graviperception). Some of these findings transcend gravitational research and are relevant to our understanding of the impact of environmental factors on CNS development on Earth.

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Fine Structures of Utricle of Developing Chick Embryo Exposed to 2G Gravity

Cited by 26 publications

References 6 publications

Ground-Based Researches on the Effects of Altered Gravity on Mice Development

Ground-Based Researches on the Effects of Altered Gravity on Mice Development

The development of vestibular system and related functions in mammals: impact of gravity

Brain development, environment and sex: what can we learn from studying graviperception, gravitransduction and the gravireaction of the developing CNS to altered gravity?

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