Development of the cerebellum in the platypus (Ornithorhynchus anatinus) and short-beaked echidna (Tachyglossus aculeatus).

The monotremes are a unique group of mammals whose young are incubated in a leathery-shelled egg and fed with milk from teatless areolae after hatching. As soon as they hatch, monotreme young must be able to maneuver around the nest or maternal pouch to locate the areolae and stimulate milk ejection. In the present study, the embryological collections at the Museum für Naturkunde, Berlin, have been used to follow the development of the monotreme cerebellum through incubation and lactational phases, to determine whether cerebellar circuitry is able to contribute to the coordination of locomotion in the monotreme hatchling, and to correlate cerebellar development with behavioral maturation. The structure of the developing monotreme cerebellum and the arrangement of transitory neuronal populations are similar to those reported for fetal and neonatal eutherians, but the time course of the key events of later cerebellar development is spread over a much longer period. Expansion of the rostral rhombic lip and formation of the nuclear and cortical transitory zones occurs by the time of hatching, but it is not until after the end of the first post-hatching week that deep cerebellar neurons begin to settle in their definitive positions and the Purkinje cell layer can be distinguished. Granule cell formation is also prolonged over many post-hatching months and the external granular layer persists for more than 20 weeks after hatching. The findings indicate that cerebellar circuitry is unlikely to contribute to the coordination of movements in the monotreme peri-hatching period. Those activities are most likely controlled by the spinal cord and medullary reticular formation circuitry.

Morphological and functional comparison of lingual papillae in suckling and adult feral cats: Forensic evidence.

Feral cats are considered as strays and are more likely to hunt in the street. We investigated the effect of environmental adaptations on the structures of lingual papillae in feral cats, which could be used as forensic evidence for their identification. There are no reported studies about the structural comparison of lingual papillae between suckling and adult feral cats. The present study described the lingual papillae of both suckling and adult cats macroscopically and microscopically via light and scanning electron microscopy. A total of nine tongue samples each for suckling and adult feral cats were examined grossly and histologically. Papillae distributions of suckling cats were similar to those observed in adult cats. Meanwhile, the shapes of those papillae were markedly different from that of corresponding papillae in adults. The change in taste bud position and size seemed to be related to the progressive growth of the papillae between adult and suckling cats; absence of taste buds in foliate papillae of feral cats at any stage; and marginal papillae which were a characteristic feature for all suckling cats. All previous elements could be affected by the specific feeding behaviour and mastication mode adaptation in suckling and adult feral cats which might help to identify suckling and adult feral cats among other breeds and animal species. We anticipate these findings may provide promising forensic evidence to discriminate between adult and suckling feral cat remains as well as prediction of environmental harshness and feeding behaviour.

Morphology of the tongue in a newborn Stejneger's beaked whale (Mesoplodon stejnegeri).

This light and scanning electron microscopic (SEM) study on the tongue of a newborn Stejneger's beaked whale (Mesoplodon stejnegeri) demonstrated a clear difference in its form from than that of other cetacean and adult Stejneger's beaked whales. This newborn Stejneger's beaked whale had a spoon-like shaped tongue. The dorsal surface in the center part of the tongue was flat and did not have papillae, but there were marginal papillae and small papillae on the anterior part of the tongue. In the posterior of the tongue, hillock-shaped papillae with taste buds on the epithelium were observed.

Corticosteroids induce the differential expression of TGFbeta isoforms, receptors and signaling in the gastric mucosa of suckling rats.

Glucocorticoids inhibit the cell proliferation in the gastric epithelium, and induce differentiation, migration and death. The mechanism by which these effects are triggered and controlled is still discussed and can involve the transcription and activation of transforming growth factor beta (TGFbeta). The present study was conducted to evaluate the effect of hydrocortisone short-term treatment on tissue level and distribution of TGFbeta isoforms, receptors and signaling through Smad2/3. To achieve that, 18-day-old rats were injected with hydrocortisone (50 mg/Kg b.wt.) for 0, 1 and 3 h. The stomachs were collected and processed for immunohistochemistry and western blotting. We observed that the treatment for 3 h increased the number of labeled epithelial cells for TGFbeta1 (p < 0.05), decreased the distribution of TGFbeta2 (p < 0.05) and did not alter TGFbeta3, TbetaRI and TbetaRII status. The levels of TGFbeta1 and receptors were checked by western blotting and results corroborate the immunodetection. We also found that phosphorylation of Smad2/3 into Smad2P increased after 3 h (p < 0.05), indicating that the high level TGFbeta1 was active on the cells. We suggest that glucocorticoids differentially regulate the expression of TGFbeta isoforms, receptors and signaling, and so TGFbeta1 might be involved in the inhibitory pathway triggered by the hormone.

Preweaning enrichment has no lasting effects on adult hippocampal neurogenesis in four-month-old mice.

Since both living in an enriched environment and physical activity stimulate hippocampal neurogenesis in adult mice, we endeavored to examine whether pre-weaning enrichment, a sensory enrichment paradigm with very limited physical activity, had similar effects on neurogenesis later in life. Mice were removed from the dams for periods of increasing length from post-natal day 7 to 21, and exposed to a variety of sensory stimuli. At the age of 4 months, significant differences could be found between previously enriched and nonenriched animals when spontaneous activity was monitored. Enriched mice moved longer distances, and spent more time in a defined center zone of the open field. Adult neurogenesis was examined by labeling proliferating cells in the dentate gyrus with bromodeoxyuridine (BrdU). Cell proliferation, survival of the newborn cells, and net neurogenesis were similar in both groups. Volumetric measurements and stereological assessment of total granule cell counts revealed no difference in size of the dentate gyrus between both groups. Thus, in contrast to postweaning enrichment, preweaning enrichment had no lasting measurable effect on adult neurogenesis. One of the parameters responsible for this effect might be the lack of physical activity in preweaning enrichment. As physical activity is an integral part of postweaning enrichment, it might be a necessary factor to elicit a neurogenic response to environmental stimuli. The result could also imply that baseline adult hippocampal neurogenesis is independent of the changes induced by preweaning enrichment and might not contribute to the sustained types of plasticity seen in enriched animals.

Changes with age in the number and size of anterior pituitary cells in female mice from suckling to adulthood.

Changes with age in the number and size of anterior pituitary cells in female mice were calculated during their postnatal development by using a stereological morphometric study with electron microscopy. The number of parenchymal cells increased in mice from 20 to 30 days of age, and did not change around puberty, after which the number increased to the adult level. The number of somatotrophs increased with age in almost the same manner as the parenchymal cells. The number of lactotrophs increased with age and were significantly different each time they were measured. The number of non-granulated cells did not increase in mice from 20 days of age to adulthood; at 20 days of age, the number was at the same level as in the adult mice. The other types of cells increased by only a small number. The sizes of all types of cells increased during postnatal life. Somatotrophs and lactotrophs became the same size as in adults by the onset of puberty. Non-granulated cells and other types of cells reached adult size at 5 days after puberty. Lactotrophs and somatotrophs had adult ultrastructural features on the day of puberty. Sizes and ultrastructural features of anterior pituitary cells reached adult levels on the day of puberty, but their numbers were still fewer than in adult mice. The increase in the volume of the anterior pituitary with age arose mostly from an increase in the number and the size of somatotrophs and lactotrophs before puberty, increases in the size of somatotrophs and the number of lactotrophs around puberty, and an increase in the number of both types of cells after puberty.

Insulin-responsive glucose transporters-GLUT8 and GLUT4 are expressed in the developing mammalian brain.

We investigated the spatial and temporal distribution of insulin-responsive facilitative glucose transporter isoforms GLUT4 and GLUT8 in the developing mouse brain. Employing Western blot analysis and specific antibodies, GLUT4 and GLUT8 peaked during the suckling phase. Immunohistochemical analysis revealed the presence of GLUT4 mainly in neurites in sensory and motor areas of cortical and subcortical structures of the brain from P7 until adulthood. In contrast, GLUT8 was found in the same anatomical structures within neurites and cell bodies. Most striking was the presence of GLUT8 in the cell bodies of the substantia nigra. We conclude that both GLUT4 and GLUT8 are present in murine brain, with highest concentrations noted during the suckling phase. These insulin-responsive isoforms may have a unique role in augmenting substrate delivery under conditions of increased demand.

A transient afferent innervation of outer hair cells in the postnatal cochlea.

In vitro retrograde labeling techniques were used to reconstruct the peripheral terminations of afferent fibers to the outer hair cells in postnatal hamsters. Between postnatal days 4 and 6, both radial and spiral afferent fibers terminated on outer hair cells. The cell bodies which gave rise to such fibers were not distinguishable. These outer radial-fiber terminations may be a transient phenomenon since they were not observed either before or after this period.

Maternal glucocorticoid hormone influences nerve growth factor expression in the developing rat brain.

Rat pups nursed from birth by mothers with increased plasma corticosterone show long-lasting biochemical and behavioral modifications. Here we have investigated nerve growth factor (NGF) concentrations in the basal forebrain, prefrontal cortex and hippocampus of both male and female offspring at 11 days of age. Maternal hypercorticosteronemia was achieved by giving corticosterone-enriched water (200 microg/ml) from delivery. There was a significant increase of NGF in the basal forebrain of both sexes and no changes in the prefrontal cortex. In the hippocampus, an increase in NGF was found in males. These results indicate that a moderate increase of corticosterone in the lactating mother modulates NGF in the developing rat. We propose that these effects contribute directly to the long-lasting behavioral and biochemical modifications in pups nursed by hypercorticosteronemic mothers.

Cortical projections to superficial laminae of the dorsal horn and to the ventral horn of the spinal cord in the North American opossum. Studies using the orthograde transport of WGA-HRP.

The orthograde transport of horseradish peroxidase conjugated to wheat germ agglutinin (WGA-HRP) has been used to study the distribution of corticospinal axons in adult and pouch-young opossums. As predicted from the results of degeneration and autoradiographic experiments, injections of WGA-HRP into limb areas of somatic motor-sensory cortex labeled axons in the dorsal and lateral funiculi of the cervical and upper thoracic spinal cord which could be traced to dense terminal zones in laminae III-VI. In addition, we obtained evidence for the presence of a few cortical axons in the ventral white matter and for innervation of the medial part of laminae I and II, laminae VII and VIII and lamina X. A few cortical axons are even present in lamina IX.

Alterations in respiratory behavior, brain neurochemistry and receptor density induced by pharmacologic suppression of sleep in the neonatal period.

UNLABELLED: The present study examined if drug suppression of active sleep (AS) in the neonate affected the development and expression of respiratory behavior. Secondly, we assessed brain neurochemistry and receptor density in specific supra-medullary brain regions to identify coincident biochemical alterations. Sprague-Dawley newborn rat pups were randomized and divided among six rat mothers (n=10/mother/group), each mother housed separately. Two untreated control (UC) groups received either no interventions or were fed milk vehicle twice daily and were handled similarly to the drug intervention animals. Pharmacological disruption of sleep was achieved by administration (2 groups of each) of either clonidine (CLO) 100 microm/kg, or scopolamine (SCO) 800 microm/kg, given orally twice daily for the first 7 days of life. On postnatal (P) days P10 and P19 of life, pups were assessed for metabolism, minute ventilation (VE), tidal volume (Vt) and frequency (f). On P21 (14 days after the end of drug exposure), pups from each condition were sacrificed and punch biopsies of the frontal cortex, hypothalamus, and hippocampus were examined for hydroxytryptophan (5-HT), and norepinepherine (NE) by HPLC. An equal number of pups were sacrificed and brains examined for muscarinic acetylcholine (mAch), alpha2-adrenergic and I1-imidazoline receptor density. RESULTS: Both CLO and SCO exposed animals had a lower V(t) and respiratory quotient than UC animals (p<0.01). CLO animals exhibited a higher f (p<0.01) and both CLO and SCO exhibited a lower V(t) (p<0.05) than the UC groups; VE was reduced in the SCO groups, compared with CLO and UC groups (p<0.01). Pattern of breathing in response to brief hypoxia exposure was altered for CLO and SCO. The normal decline in VE during sleep was not observed in CLO rats. Both drug exposures resulted in a comparable reduction in hypothalamic NE and 5-HT levels (p<0.05), while in the frontal cortex, and the hippocampus variable changes in NE and 5-HT, occurred. In CLO and SCO rats mAch receptors were increased in cortex, and reduced in hypothalamus; I1-imidazoline receptors were increased in hypothalamus and decreased in hippocampus (p<0.05 for each). In contrast, alpha2-adrenergic receptors were increased in cortex for both CLO and SCO, decreased in hypothalamus for CLO, and decreased in hippocampus for SCO (p<0.05 for each). CONCLUSIONS: these data show that drug-induced neonatal sleep suppression will alter ventilatory pattern, metabolism, and site-specific concentrations of adrenergic neurotransmitters and in receptor density, perhaps as a result of suppression of neonatal AS.

Scanning electron microscopic changes in vaginal epithelium of suckling neonatal mice in response to estradiol or insecticide chlordecone (Kepone) passage in milk.

Groups of lactating mice received daily 9 intraperitoneal injections consisting of the following chemicals: sesame oil only or 10.0, 20.0 or 40.0 micrograms estradiol-17 beta or 250.0, 500.0 or 1000.0 micrograms chlordecone. Reproductive tracts and vaginal surface changes were examined in the neonates that were nursed by the treated lactating dams for 12 days. Ingestion of milk from dams treated with estradiol or chlordecone did not produce any toxic symptoms or mortality in the offspring. However, the neonatal reproductive tract weights and vaginal epithelium exhibited significant changes indicating the passage of these compounds in milk. The vaginal epithelium in the neonates that nursed the estradiol-treated dams exhibited mucification, keratinization, and desquamation. Neonates that ingested milk from chlordecone-treated dams exhibited similar but dose-dependent changes in the vaginal canals. However, the keratinized vaginal cells in these mice were morphologically different and lacked the well-developed microridge patterns on the cell surfaces that characterized keratinized cells in the estradiol group. The significance of these changes on the reproductive functions in adult animals are discussed in the text.

Ultrastructural identification of Merkel cells around the mouth of the newborn marsupial.

The ultrastructure of the epidermal cells surrounding the mouth of three newborn marsupial species, the Northern native cat Dasyurus hallucatus, the brush tail possum Trichosurus vulpecula and the Northern brown bandicoot Isoodon macrourus were examined. The presence of Merkel cells, highly sensitive touch receptors, would suggest that the sense of touch aids the relatively underdeveloped newborn marsupial to move from the urinogenital sinus to the pouch and to locate the teat.

Morphogenesis of the special circular muscle layer and of the interstitial cells of Cajal related to the plexus muscularis profundus of mouse intestinal muscle coat. An E.M. study.

The morphogenesis of the special layer and the interstitial cells of Cajal (ICC) related to the plexus muscularis profundus (PMP) of mouse intestinal muscle coat has been studied in foetuses at term, neonates not yet fed, suckling animals, weaning animals and adult animals. In foetuses at term, the special layer is absent, but presumed myoblasts of this layer are recognized in the tela submucosa facing the developing circular layer. The ICC, too, are not differentiated and presumed ICC-blasts are tentatively identified in submucosal cells related to nerve fibers. These nerve fibers are considered to belong to the developing PMP. In neonates, the special layer, ICC and PMP are recognizable, but are made up of poorly differentiated elements. In suckling animals, these three structures develop but become almost fully differentiated only at the end of the weaning period, whereas the other components of the muscular coat are already developed.

Cytodifferentiation of the interstitial cells of Cajal related to the myenteric plexus of mouse intestinal muscle coat. An E.M. study from foetal to adult life.

The cytodifferentiation of the interstitial cells of Cajal (Type I) related to the myenteric plexus of the mouse intestinal muscle coat was studied in foetuses at term, neonates not yet fed, suckling animals, weaning animals and adult animals. In foetuses at term, interstitial cells of Cajal and their precursor cells are not identifiable. In neonates not yet fed, presumed precursor cells of the interstitial cells of Cajal, i.e. ICC-blasts, can be identified as cells surrounding the developing myenteric plexus and interposed between the circular and longitudinal muscle layers. These ICC-blasts are poorly differentiated but, like the adult interstitial cells, are always related to nerve endings and possess large and numerous mitochondria. In suckling animals these cells gradually develop, and are fully differentiated only after the end of the weaning period.

Effect of dietary soybean meal on the microscopic anatomy of the small intestine in the early-weaned pig.

Two experiments were conducted to determine the effect of soybean meal in postweaning diets on villus height (VH), villus shape and lamina propria depth (LPD) in the small intestine. Intestinal samples were taken at 25, 50 and 75% of the small intestine's length. The first experiment determined the normal effects of age on these structures in nursing pigs from 9 to 36 d of age. Villus height decreased (P less than .01 at the 50 and 75% locations) and LPD increased (P less than .01 at the 25% location) in a quadratic fashion with increasing age. In the second experiment, pigs were weaned at 21 d of age and fed one of three 20% protein diets: 1) protein from hydrolyzed casein (CAS), 2) soybean meal (SBM) or 3) a conventional corn-soybean meal diet (CSBM). Intestinal samples were taken 0, 3, 6, 9, 12 and 15 d post-weaning. Villus height decreased dramatically the first 3 d postweaning, with a continuing decline until 12 d post-weaning. Averaged over the d 3 to 15 interval, VH were generally greater for pigs fed CAS than for pigs fed CSBM or SBM. Pigs fed SBM or CSBM had deformed villi, and pigs fed SBM had greater (P less than .05) LPD at all intestinal locations, suggesting less mature enterocytes on the villi. These data suggest that feeding high concentrations of soybean meal to the pig post-weaning has a detrimental effect on the small intestine, but this effect was minimized when soybean meal was fed as part of a corn-based diet.

Supplemental silicon increases plasma and milk silicon concentrations in horses.

The primary objective of this research was to determine the effect of supplemental dietary silicon (Si) on plasma and milk Si concentrations of lactating mares and the subsequent effect on plasma Si concentrations in nursing foals. Additionally, the role of Si on altering biochemical markers of bone turnover was investigated, because supplemental Si may be advantageous in enhancing bone health. Twelve Arabian mare/foal units were pair-matched by foaling date and randomly assigned to two groups, Si-supplemented (Supplemented) or control (Control). Blood and milk samples were taken on d 0, 15, 30, and 45, d 0 being the 1st d after parturition. Plasma and milk (or colostrum) Si concentrations were determined and serum was analyzed for osteocalcin, carboxy-terminal pyridinoline cross-linked telopeptide region of type I collagen, and pyridinoline and deoxypyridinoline crosslinks. All Supplemented mares had higher (P < 0.01) plasma Si concentrations than Control by d 30, and Supplemented mares' milk had higher (P < 0.01) Si concentrations on d 45 than Control mares' milk. By d 45, foals of Supplemented mares had higher (P < 0.01) plasma Si concentrations than foals of Control mares. Supplemental Si did not influence (P > 0.36) bone metabolism in foals; however, trends (P < 0.10) for altered bone metabolism were observed in postpartum mares. Results indicate that supplemental Si increases plasma and milk Si concentrations. Further research is required to determine whether Si has a role in altering serum biochemical markers of bone and collagen activity.

Effect of double nursing on some anatomical and physiological properties of the digestive tract of rabbits between 23 and 44 days of age.

Anatomical and physiological properties of the digestive tract were examined and compared in young rabbits nursed either by one (SS) or by two does (DD) daily up to the age of 35 days. At the age of 23, 30, 37 and 44 days, 8 young per treatment were euthanised. Double suckling and the subsequent higher level of solid feed intake after weaning were found to exert a stronger influence on the weight of the entire gastrointestinal tract and that of its individual parts (the stomach, small intestine, caecum and colon) than on its length. The quantity of the gastric content was found to rise with advancing age in both groups (from 36 to 70 g and from 37.5 to 79 g). In both groups the pH of the stomach was higher during the suckling period (4.5-5.3) than subsequent to weaning (1.6-2.4). The quantity of the caecal content also increased with age (from 4 or 8 g), but on the 37th day significantly higher quantities of caecal content were recorded in DD rabbits (50.5 g compared with 35 g). The pH of the caecal content decreased more slowly from an initial high value (6.0 and 6.5 in SS and DD rabbits, respectively), and by the 37th day had settled at a low value (5.7-5.8) in both groups. The dry matter content of the caecal content decreased from 270-273 g to 188-207 g in both groups. Total volatile fatty acid (tVFA) and acetic acid (C2) concentration, which amounted to 66-88% of tVFA, rose; in SS rabbits they were at higher levels by the 30th day (53.6 and 42.2 mmol/L, respectively), and remained at an increased level until the 44th day (P < 0.05). The ratio of C3: C4 was high on the 23rd day (2.5 and 2.4), but dropped at the age of 30 days (0.5 in SS and 1.7 in DD, P < 0.05) and, further, by the 37th day (0.2 in SS). In SS rabbits coliform count proved significantly lower (10(5)) on the 23rd day than in DD rabbits (10(6)). By the 37th day this count had decreased in both groups and subsequently remained at a low level (< 10(4)). By the 23rd day Bacteroides were present in large quantities (10(8)) in the caecum and showed no change with advancing age or feeding regime.

Morphofunctional adaptations of the olfactory mucosa in postnatally developing rabbits.

Rabbits are born blind and deaf and receive unusually limited maternal care. Consequently, their suckling young heavily rely on the olfactory cue for nipple attachment. However, the postnatal morphofunctional adaptations of olfactory mucosa (OM) are not fully elucidated. To clarify on the extent and the pattern of refinement of the OM following birth in the rabbit, morphologic and morphometric analysis of the mucosa were done at neonatal (0-1 days), suckling (2 weeks), weanling (4 weeks), and adult (6-8 months) stages of postnatal development. In all the age groups, the basic components of the OM were present. However, proliferative activity of cells of the mucosal epithelium decreased with increasing age as revealed by Ki-67 immunostaining. Diameters of axon bundles, packing densities of olfactory cells, and cilia numbers per olfactory cell knob increased progressively with age being 5.5, 2.1, and 2.6 times, respectively, in the adult as compared with the neonate. Volume fraction values for the bundles increased by 5.3% from birth to suckling age and by 7.4% from weaning to adulthood and the bundle cores were infiltrated with blood capillaries in all ages except in the adult where such vessels were lacking. The pattern of cilia projection from olfactory cell knobs also showed age-related variations, that is, arose as a tuft from the tips of the knobs in neonates and sucklings and in a radial pattern from the knob bases in weanlings and adults. These morphological changes may be attributed to the high olfactory functional demand associated with postnatal development in the rabbit.