ISSN:
1432-0568
Keywords:
Human brain
;
Prenatal ontogeny
;
Monoamine neurons
;
Fluorescence histochemistry
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary The distribution of monoamine neurons in the human fetal brain was studied by Falck-Hillarp fluorescence histochemistry. Catecholamine (CA)- and 5-hydroxytryptamine (5-HT)-neuron systems were found in the smallest brain studied, obtained from an embryo having a total length of 2.1 cm and a gestational age of 7 weeks. A marked proliferation and differentiation of the monoamine neuron systems took place between the 7th and 23rd week of gestation (the range covered in the present investigation) permitting a mapping of major cell groups, as well as several axon pathways and terminal innervation patterns. The basic cytoarchitectonic features of the central monoamine neurons in human fetuses were strikingly similar to those of the fetal rat. Thus, a large complex of cell bodies was found in the developing substantia nigra area, in all probability the CA neurons of the nigro-striatal dopamine system. Axons projected towards the corpus striatum. Here, the putamen and, somewhat later, the caudate nucleus became richly innervated by CA nerve terminals. Small clusters of CA nerve cells were found in the hypothalamus, e. g. in the ventral periventricular area. 5-hydroxytryptamine nerve cell bodies were distributed throughout the raphe areas from the medulla oblongata to the mesencephalon forming several well delineated groups, e.g. a large group in the area of nuc. raphe dorsalis. 5-HT axons projected caudally in the ventral parts of the medulla oblongata and into the spinal cord and rostrally through the mesencephalon and into the forebrain. CA cell bodies were also found in several large complexes of the medulla oblongata and pons, where such cell bodies are of the noradrenaline type in animals. The principal locus coeruleus consisted of densely packed fluorescent cells and several loosely packed groups extended laterally, medially, dorsally and rostrally from this area. Several axon bundles ascended dorsally from this complex. Ventrally and dorsally located CA cell groups were found in the medulla oblongata, and green fluorescent axons descended into the spinal cord. Varicose nerve terminals of the CA type were found, e.g. in the spinal cord, around the third ventricle and, using brain smears, also in the developing cerebral and cerebellar cortices. There seemed to be an outflow of CA axons in ventral nerve roots of cranial and spinal nerves. The developing pineal gland showed scattered 5-HT-containing parenchymal cells. Area postrema contained a number of strongly fluorescent CA cells and some weaker fluorescent 5-HT cells.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00519968
Permalink
