Altricial

The early VN neurones migrate by various routes and in mammals become organised into two layers, each with distinct functional attributes (Chaps. 2 and 6). Amongst marsupials, the sensory cells of an opossum appear at about one-week post-conception (Jia and Halpem, 1998). Despite their extremely altricial developmental pattern, the bandicoots dendrites produce sensory processes (Fig. 4.5) on the lumenal border of the VNO at 35 days postnatal, which in the Northern Bandicoot (Isoodon macrourus) is about 50% of pouch life (Kratzing, 1986). 

The developmental changes seen in the immediate postnatal period in altricial rodents and especially in the early stages of marsupials, are an expected outcome of their shortened gestational period, early parturition and consequential dependent status. Regrettably, the relative contribution of the main and accessory chemosensory route(s) cannot be fully assessed. The lesser importance of the AOS (by some tests)... 

Several studies have identified responses that do not involve VN participation, from marsupials to Mouse-lemurs. Where the chosen endpoint is totally unaffected by absence of the organ and in addition is dependent upon MOS activity, then it needs to be classified as VN-independent. Where VN-x results are ambiguous, as already considered for opossums (Monodelphis domestica), further analysis is desirable. For instance, Goats do not use AOS input for mating, only urinalysis, although experiential variables have not been fully explored (Ladewig et al., 1980). Examples of VN independence then exist in both altricial and precocial species. 

Ultra-sound emissions typically occur when male rodents are exposed to female odours or altricial neonates to maternal sources (Whitney, 1974 Conely and Bell, 1978). Without the VNO, sexually inexperienced male mice do not utter emissions at ultra-high frequencies (UHF), whereas those with prior experience vocalise after VN-x, as discussed above (Chap. 5). Female mouse urine contains a unique UHF-eliciting component which is non-volatile but ephemeral (Sipos et al., 1995). The signal is degraded by oxidation and disappears within 15 to 18 hours of deposition. Direct contact with freshly voided urine must occur before males will vocalise (sexually experienced or inexperienced). At least one of the olfactory systems is needed for UHF to be elicited by fresh urine complete deafferentation abolishes the response (Sipos et al., 1993). Exposure to females permits UHF to be elicited by other than chemical cues (Labov and Wysocki, 1989). Nocturnal or cryptic species conceivably use ultrasound to advertise male presence whether this is to deter other males or assist with female location is unclear. 

Rosenblatt l.S. (1983). Olfaction mediates developmental transition in the altricial newborn of selected species of mammals. Dev Psychobiol 16, 347-375. 

Developmental Predictors of Coloration in Altricial Birds Studies of... 

DEVELOPMENTAL PREDICTORS OF COLORATION IN ALTRICIAL BIRDS STUDIES OF BLUE TITS AND GREAT TITS... 

The newborns of birds including chickens and of some mammals such as guinea pigs and sheep can open their eyes, eat, and exhibit sleep-wake cycles similar to those found in adulthood (1—4) these animals are precocial species. The newborns of other mammals such as those of rats, cats, and rabbits are not able to open their eyes at birth and have very different sleep-wake states from their adulthood (4,5). These species are altricial mammals. There are also a variety of developmental and anatomical brain differences in altricial and precocial species that appear to relate to learning and experiential development (1). 

Considering the fact that an increase in the percentage of wake parallels the decrease of REM sleep, the wake/REM (W/R) ratio might be an important index to describe the developmental levels in altricial mammals. This ratio is about 0.4 (28%/72%) in the first 10 days of life in the rat (4), dramatically increases to 1.77 at PN 21, 3.99 at PN 26 (9), and 8.1 in adulthood (calculated from Ref. 152). This ratio is 1.0 in the human newborn and is 2.6,10.3, and 11 at PN 1, PN 14-18, and adult, respectively (calculated from Ref. 12). The developmental features of sleep-wake states suggest that the strong REM sleep propensity in neonates is progressively suppressed or that a REM sleep inhibitory process is immature in neonatal rats. 

Brunjes, P.C. (1983) Olfactory bulb maturation in Acomys cahirinus , is neural growth similar in precocial and altricial murids Dev. Brain Res., 8, 335-341. 

Nestlings of altricial species (those confined to the nest for some time after hatch) may be considerably more sensitive to lead exposure than adults, and also more sensitive than hatchlings of many precocial species. Hatchlings of precocial species, including chickens, Japanese quail, mallards, and pheasants, are relatively tolerant to moderate lead exposure, i.e., there was no effect on growth at dietary levels of 500.0 mg Pb/kg, or survival at 2000.0 mg Pb/kg. 

Leon, M., Coopersmith, R., Ulibarri, C., Porter, R. H., Powers, J. B., 1984, Development of olfactory bulb organization in precocial and altricial rodents. Develop. Brain Research, 12 45. 

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