Talk:Neural - Medulla Oblongata Development

2008

The development of nicotinic receptors in the human medulla oblongata: inter-relationship with the serotonergic system

Auton Neurosci. 2008 Dec 15;144(1-2):61-75. Epub 2008 Nov 5.

Duncan JR, Paterson DS, Kinney HC.

Department of Pathology, Children's Hospital Boston and Harvard Medical School, Boston, Massachusetts 02115, USA. jhodie.duncan@childrens.harvard.edu Erratum in:

Auton Neurosci. 2009 Jan 28;145(1-2):108. Abstract Maternal cigarette smoking during pregnancy adversely affects fetal development and increases the risk for the sudden infant death syndrome (SIDS). In SIDS we have reported abnormalities in the medullary serotonergic (5-HT) system, which is vital for homeostatic control. In this study we analyzed the inter-relationship between nicotinic receptors (nAChRs), to which nicotine in cigarette smoke bind, and the medullary 5-HT system in the human fetus and infant as a step towards determining the mechanisms whereby smoking increases SIDS risk in infants with 5-HT defects. Immunohistochemistry for the alpha4 nAChR subunit and 5-HT neurons was applied in fetal and infant medullae (15-92 postconceptional weeks, n=9). The distribution of different nAChRs was determined from 39-82 postconceptional weeks (n=5) using tissue autoradiography for 3H-nicotine, 3H-epibatidine, 3H-cytisine, and 125I-bungarotoxin; the findings were compared to laboratory 5-HT1A and 5-HT transporter binding data, and 5-HT neuronal density. Alpha4 immunoreactivity was ubiquitously expressed in medullary nuclei related to homeostatic functions from 15 weeks on, including rhombic lip germinal cells. At all ages, alpha4 co-localized with 5-HT neurons, indicating a potential site of interaction whereby exogenous nicotine may adversely affect 5-HT neuronal development and function. Binding for heteromeric nAChRs was highest in the inferior olive, and for homomeric nAChRs, in the vagal complex. In the paragigantocellularis lateralis, 5-HT1A receptor binding simultaneously increased as alpha7 binding decreased across infancy. This study indicates parallel dynamic and complex changes in the medullary nicotinic and 5-HT systems throughout early life, i.e., the period of risk for SIDS.

PMID: 18986852

2006

Morphometric development of the posterior funicular nucleus in the human medulla oblongata

Ma X, Goto N, Goto J, Nonaka N, Shibata M. Okajimas Folia Anat Jpn. 2006 Aug;83(2):35-42.

Abstract Using serial sections of 11 human brains of fetuses 18-40 weeks of gestation (WG), 2-month-old infant and 63-year-old adult, we conducted the quantitative analysis of the development of the posterior funicular nucleus (PFN) in the medulla oblongata. The results suggest the following: (1) The cells of the human cuneatus lateralis nucleus are easily distinguished from those of the gracilis nucleus and cuneatus medialis nucleus because the neuronal somatic areas are the largest; the smallest neuronal areas are in the cuneatus medialis nucleus. (2) The development of the PFN occurs at least in four stages characterized by the degree of maturation of the neurons: (a) immature neuronal stage before 20 WG, (b) preparatory stage between (a) and (c), (c) accelerated development stage from 30 to 40 WG, and (d) postnatal stage. The development of the human posterior funicular nucleus accelerates after 30 WG, and postnatal qualitative maturation also occurs. Developmental differences of the three nuclei of the PFN in the medulla oblongata are presented and discussed from the morphological and morphometric point of view.

PMID: 16944836 http://www.ncbi.nlm.nih.gov/pubmed/16944836

2003

Development of catecholaminergic neurons in the human medulla oblongata

Life Sci. 2003 Jul 25;73(10):1315-31.

Lorke DE, Kwong WH, Chan WY, Yew DT.

Department of Neuroanatomy, Institute of Anatomy, University Hospital Eppendorf, Martinistr. 52; D 20246 Hamburg, Germany. lorke@uke.uni-hamburg.de Abstract Distribution and maturation of catecholaminergic (CA) neurons have been studied by tyrosine hydroxylase immunohistochemistry in the medulla oblongata of human fetuses aged 14.5-25 weeks of gestation. Already at 14.5 weeks, CA neurons were observed in two longitudinally oriented cell clusters, one located ventrolaterally in the area of the lateral reticular and ambiguous nuclei, the other one dorsomedially forming 4 groups related to the dorsal vagal nucleus, the commissural nucleus of the vagus, the nucleus of the tractus solitarius and the area postrema. CA neurons in the area postrema were often found close to blood vessels. Scattered intermediate CA neurons were seen between these two larger clusters. CA neurons still appeared immature exhibiting bipolar morphology with only one or two short stout processes, which hardly branched. At 21 weeks, CA neurons occupied essentially the same location, but had a more mature morphology. Though still bipolar in shape, they had thinner and much longer processes which frequently branched. Both in the ventrolateral and the dorsomedial cell clusters, these processes were frequently lying close to blood vessels. At 25 weeks, CA cells had matured into multipolar neurons with long thin processes forming fine fiber networks in the ventrolateral medulla as well as around and within the dorsal vagal and solitarius nuclei. Only at this stage, a distinct CA fiber tract was seen located in the region of the tractus solitarius. Our results indicate that CA neurons in the human medulla, which are presumably involved in the control of ventilation and blood pressure, though generated rather early during development, mature relatively late.

PMID: 12850246