No abstract

The ontogenetic development and cell differentiation of the mesencephalic trigeminal nucleus (Ntm) is lightmicroscopically examined in 58 bovine embryos and fetuses ranging from 2.4 to 80 cm Crown-Rump-Length (CRL). The cytoarchitecture and fine structure in adult cattle, sheep, and goats are investigated with the aid of light- and electronmicroscopy. At 2.4 cm CRL, the proneurons of the Ntm are detectable for the first time within the ventricular zone of the alar plate, possessing one drop-like cytoplasmic protrusion, whereas at 5 cm CRL, two cell types with differing sizes appear. Up to a CRL of 11.5 cm, the nucleus shows advanced maturation processes and has reached his final position at the border of the mesencephalic central grey. From 26 cm CRL onward, three cell types, and at 34 cm CRL four cell types, are discernible based on their nissl-granule arrangement. The cytomorphological differentiation and the maturation of the cells proceeds until 56 cm CRL, at which point the topographical and cytological characteristics of the Ntm are comparable with those of adult animals. In adult cattle, sheep and goats the Ntm consists of large (40-60 microns) and scarce medium-sized (30-40 microns) neurons with round and oval shapes. Scarcer small (20-25 microns) round and medium-sized multipolar neurons occur. The Nissl bodies are scattered throughout the pericaryon of the large neurons in a dust-like pattern and in the medium-sized neurons in a grained form. Within the cytoplasmic streets, which are situated between the membranes of the rough ER, numerous neurofilaments and mitochondria are detectable. Large Golgi complexes are placed in a perinuclear position. The neurons are also characterized by some somatic spines, and by a moderate distribution of axosomatic synapses, in which axon-endings with flattened synaptic vesicles predominate.

In the present study of nutrition control of Wistar white rats, the ultrastructure of cerebellar Purkinje cells was studied after chronic ethanol exposure and a subsequent period of prolonged abstinence: a qualitative investigation of the perikarya of Purkinje cells was performed in age-matched controls (group A) and rats alcohol-fed for 5 months and withdrawn from this diet for 3 months (group B). The results showed massive accumulation of small dense bodies as well as obvious deposition of lipofuscin in the Purkinje cells of group B. Furthermore, ring-shaped Golgi apparatus units, lamellar bodies and degenerative foci dispersed throughout the cytoplasm of the alcohol-treated animals referred to degeneration processes and neuronal cell death, the morphological characteristics and the aetiology of which are discussed.

I n order to investigate the fine structure of the didten's Bulbus olfactorius a n d to determine differences between birds and mammals, tissue specimen were taken from 26 animals. The following techniques were used: Luxol-Fast-Blue-a n d Nisslstaining, Bodian impregnation. Marked differences between the Bulbus of chidten a n d mammals were found lightmicroscopically in the number of the cell layers and the localization and size of cells.The electronmicroscope revealed that the cell organelles a n d the different types of synapses resembled the ones found in mammals. The mitral cells of the hen contrary to the ones of mammals often contained lamellar bodies.

No abstract