Transient expression of NF200 by fibers in the nasal septum and rostral telencephalon of developing opossums (Monodelphis domestica).

Marsupials are born very immature and crawl on their mother's belly to attach to teats. Sensory information is required to guide the newborn and to induce attachment to the teat. Olfaction has been classically proposed to influence neonatal behaviors, but recent studies suggest that the central olfactory structures are too immature to account for them.

Facial Mechanosensory Influence on Forelimb Movement in Newborn Opossums, Monodelphis domestica.

The opossum, Monodelphis domestica, is born very immature but crawls, unaided, with its forelimbs (FL) from the mother's birth canal to a nipple where it attaches to pursue its development. What sensory cues guide the newborn to the nipple and trigger its attachment to it? Previous experiments showed that low intensity electrical stimulation of the trigeminal ganglion induces FL movement in in vitro preparations and that trigeminal innervation of the facial skin is well developed in the newborn. The skin does not contain Vater-Pacini or Meissner touch corpuscles at this age, but it contains cells which appear to be Merkel cells (MC).

Cephalic sensory influence on forelimb movement in newborn opossums, Monodelphis domestica.

Like other marsupials, the opossum Monodelphis domestica is born very immature and crawls, unaided by the mother, from the urogenital opening to a nipple where it attaches and pursues its development. If the alternate, rhythmic movements of the forelimbs which allow this locomotion are generated by the developing spinal motor networks, sensory information is nonetheless needed to guide the newborn to a nipple. Behavioral, anatomical and physiological studies suggest that the auditory and the visual systems are insufficiently developed in newborn opossums to influence spinal motor centers, while the vestibular, trigeminal, and olfactory systems are likelier candidates.

Distribution of the neuronal gap junction protein Connexin36 in the spinal cord enlargements of developing and adult opossums, Monodelphis domestica.

We use opossums Monodelphis domestica to study the development of mammalian motor systems. The immature forelimbs of the newborn perform rhythmic and alternating movements that are likely under spinal control. The hindlimbs start moving in the second week.

Comparing the retinal structures and functions in two species of gulls (Larus delawarensis and Larus modestus) with significant nocturnal behaviours.

Ring-billed gulls (Larus delawarensis) and gray gulls (Larus modestus) are two species active both by day and night. We have investigated the retinal adaptations that allow the diurnal and nocturnal behaviours of these two species. Electroretinograms and histological analyses show that both species have a duplex retina in which cones outnumber rods, but the number of rods appears sufficient to provide vision at night.