Influences of meningeal cells on brain development

Destruction of meningeal cells during brain development results in alterations of the extracellular matrix over the surface of the central nervous system, and a regional disruption of the external glial limiting membrane, associated with a reorganization of the glial scaffold. These changes of the glial organization have repercussions on neuronal migration and aggregation leading to a failure of neurons to segregate into spatially separated layers and lobules. We propose that meningeal cells stabilize the labile outer surface of the brain and the glial scaffold during development by specifically controlling the composition of the extracellular matrix at the interface with glial end-feet.     

Prenatal diagnosis and perinatal management of a fetal ovarian cyst

A case of a prenatally diagnosed fetal ovarian cyst is presented. The pregnancy was complicated only by polyhydramnios, and some degree of fetal bowel obstruction could be recognized on sonogram. The newborn was delivered vaginally in the 39th week of pregnancy, and the cyst was removed by laparotomy on the day of the delivery. The etiology of this rare fetal condition is unknown.     

Lactation performance of guinea pigs (Cavia porcellus) does not respond to experimental manipulation of pup demands

To ensure proper development of young, mothers should react to offspring signals of need. Studies of such parent-offspring interaction often manipulated litter size to measure effects of changed offspring food demand. We used the extreme precociality of guinea pig (Cavia porcellus) pups to increase offspring demand without changing any other litter characteristic. As pups contribute to their own energy demands from birth by independent feeding, their food demand can be increased by withholding solid food early in lactation. We studied whether mothers reacted to increased food demand of offspring by enhanced parental care, especially by changes in the pattern of milk production and nursing. Pups deprived of solid food early in lactation grew more slowly and were in poorer body condition than pups in control litters, even after the former had access to solid food in late lactation. Mothers of deprived young reacted to offspring long-term need by maintaining nursing behaviour for longer than control mothers. However, this change in behaviour did not occur early in lactation when pup short-term need was greatest nor did it result in increased milk transfer at any time. Energy allocation of mothers measured by changes in their food intake, maternal body reserves, and milk production stayed the same whether offspring had early access to solid food or not. Thus mothers did not increase energy allocation to pups even though they apparently had information about the pups' poor state.     

Males in the shade: habitat use and sexual segregation in the Galápagos sea lion (Zalophus californianus wollebaeki)

In many sexually dimorphic species adult sexes tend to segregate socially, spatially, or in habitat use. Several hypotheses have been formulated regarding underlying mechanisms. We investigated terrestrial habitat use and sexual segregation in a tropical otariid, the Galápagos sea lion (Zalophus californianus wollebaeki), where most of the hypotheses can be ruled out a priori. Factors relating to thermoregulation and costs of locomotion were of prime importance for habitat use. Habitats directly adjacent to the sea, with simple structured flat surfaces, shade, and tide pools were most frequented, but sexes and age classes differed in their usage patterns. Sexual segregation, both spatial and by habitat was pronounced in the reproductive period (RP), but remained high during the nonreproductive period (NRP). A GLM model of habitat use showed that in both seasons adult males frequented habitat types that adult females and other age classes used much less. Males were most abundant in suboptimal inland habitats, which offered only shade for cooling. Females with newborns differed in habitat use from females with older offspring and lone females. Spatial and habitat segregation are explained most parsimoniously as by-products of social processes, primarily intrasexual competition and female avoidance of male harassment, linked to the polygynous mating system.Electronic Supplementary Material Supplementary material is available in the online version of this article at and is accessible for authorized users.