Growth cones in the superior cervical sympathetic ganglion in human foetus aged 23 weeks

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

Nerve cells and synapses in the human foetal hypogastric nerves

The hypogastric nerves of a human foetus of 220 mm C-R length (23rd week) were investigated with an electron microscope. These nerves were composed mainly of bundles of unmyelinated fibres and single myelinated fibres. Small ganglia and single ganglion cells were observed in the hypogastric nerves. Light and dark cells were found among the nerve cells. The two types of cell differed in the number of ribosomes and the amount rough endoplasmic reticulum. In the period of development investigated protosynapses and mature synapses were observed in the hypogastric nerves

Formation of synapses on the growth cones in human embryonic inferior ganglion of the vagus

Ultrastructural study was performed on inferior ganglia of the vagus in human embryos aged 7 and 8 weeks (developmental stages 18 to 23, 44 to 56 days). The growth cones are observed between the bundles of axons of the inferior ganglia of the vagus. Many primitive synapses (protosynapses) between dendritic and axonal growth cones are observed

An ultrastructural study of the myelination of the trigeminal ganglion in human foetuses aged 10 to 23 weeks

An ultrastructural study was performed on trigeminal ganglia removed from foetuses aged 10 to 23 weeks. The first turns of lemmocyte processes around the axons were observed in the trigeminal ganglion in the 12th week of development. During the period between the 15th and the 18th weeks the myelin sheath increases in thickness and becomes a compact, laminated structure. In foetuses of 23 weeks the compact myelin sheath has up to 24 myelin lamellae

Development of the myelin sheath of the hypogastric nerves in a human foetus aged 23 weeks

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 myelinated fibres had thick compact laminated myelin. The number of myelin lamellae on a single fibre was 22

The origin of cells of the cochlear ganglion in early human embryos

The study was conducted on 6 human embryos at stage 13. It was found that the facial-vestibulocochlear complex is closely related to the otic vesicle, and the particular components of that complex may be distinguished. They show different cellular arrangement and shape. The neural crest cells migrating from the dorsal hindbrain are continuous with cells forming the cochlear ganglion. This gives evidence for neural crest contribution to the cochlear ganglion

Scanning electron microscopic study of the fibrous rings of the arterial orifices in embryos of the 7th and 8th weeks

The arterial fibrous rings were investigated in human embryos aged 7 and 8 weeks under light and scanning electron microscopes. In the present study it was shown that the arrangement of collagen and formation of fibres changes rapidly within one week. In the 7th week there are no collagen fibres and the netlike fibrils extend between processes of fibroblasts. At the end of the 8th week the collagen fibres are formed and they have different arrangements in the particular layers of the fibrous rings. (Folia Morphol 2010; 69, 3: 180-183

The structure of the cusps of valves in the human foetal great saphenous vein

The study was performed on 110 great saphenous veins in human foetuses of both sexes aged 9 to 37 weeks. The earliest well-shaped valves were observed in foetuses aged 13 weeks. In these foetuses the number of valves varies from 2 to 7. Consecutive microscopic sections revealed that the developing valves at their origin present thickening of the endothelium which is continuous into the cusps of the valves. The bicuspid cusps are crescent-shaped and both surfaces are lined by endothelium

Foramina on the internal aspect of the alveolar part of the mandible

Observations were made on 299 dry human mandibles and 21 autopsy heads. Foramina were observed in the inner surface of the alveolar part in 32% of the mandibles investigated. The diameter of the foramina varied between 0.4 mm and 1.6 mm. In most instances foramina were present between the lower medial and lateral incisors but in some cases they were also observed in the midline or between the lower lateral incisors and canines. Histological studies confirmed the presence of a neurovascular bundle in the accessory foramina. This bundle was formed by branches of the mylohyoid nerve, sublingual artery and accompanying veins