The formation of the myelin sheath of the human hypogastric nerves was studied by electron microscopy in a foetus of 23 weeks of postovulatory age (220 mm C-R length). In the investigated foetus the hypogastric nerves were mainly composed of bundles of unmyelinated fibres. The myelinated fibres were seen to be at different stages of myelination. Well… (More)
In embryos at stage 13th vestibulocochlear ganglion forms a complex structure with the geniculate ganglion. The geniculate ganglion is placed rostrally and may be distinguished from the vestibulocochlear ganglion. Also at this stage there is a sign of differentiation of the vestibular and cochlear ganglia.
The formation of the myelin sheath of the human phrenic nerve has been studied by electron microscopy in fetuses aged 15, 17, and 23 postovulatory weeks. At 15 weeks, the phrenic nerve is composed mainly of large bundles of axons surrounded by lemmocyte processes. However, fibres at the beginning of myelination are present and show one or one and a half… (More)
A study was made on 18 embryos of developmental stages 13-15 (5(th) week). Serial sections made in horizontal, frontal, and sagittal planes were stained with routine histological methods and some of them were treated with silver. In embryos of stage 13, the otic vesicle is at the rhombomere 5, and close to the vesicle is the facial-vestibulocochlear… (More)
Ultrastructural study was conducted on the superior cervical sympathetic ganglia in human foetus aged 23 weeks. It was shown that in investigated foetus the nerve fibres in the ganglion were in different phases of myelination. Also growth cones, which present evidence of still growing fibres, were observed.
Studies of serial sections and reconstructions of embryos at stage 13 (32) postovulatory days) revealed that the cranial neural tube in the investigated embryos possesses 15 neuromers: 1 telencephalic, 3 diencephalic, 3 mesencephalic, and 8 rhombencephalic. Within the primary efferent column all nuclei of the cranial nerves may be distinguished. Also fibers… (More)
The mesencephalic nucleus of V was investigated in embryos of developmental stages 14 and 15. In stage 14 the nucleus is formed by a small group of cells lying a little rostrally to the sulcus limitans in the pontine flexure. In stage 15 the cells of the nucleus are also found in the anterior crus of the pontine flexure. The nucleus is composed of oval… (More)
The trigeminal nucleus was investigated on serial sections of 74 human embryos of developmental stages 13 to 23 (28 to 56 days). The main nucleus was identified in embryos of stage 13 in the alar lamina. With advancement of the development the nucleus enlarges anteriorly and posteriorly, and is always located dorsally and laterally to the motor trigeminal… (More)