Attempts of these studies were made to investigate the nonspecific congenital focal accumulation of ectodermal glial cells in the brain of normal piglets. The brain samples were taken from 1-,10-,20-,35-,45- and 70-day-old piglets from a SPF-pig farm and three model pig farms. Occurrences of neuroglial cell foci (NCF) on the brain were observed with light microscope. Appearance degrees of the congenital NCF on 10 to 16 cross section slides per a pilleta brain were tentatively designed on a scale from degree+ to +++by NCF number: +, less than 20 of NCF number; +++, 21-40 of NCF number: +++, more than 41 of NCF number.
The results obtained were as follows :
1. NCF in the brain were observed mainly on the cerebrum. Regions of higher frequencies on the cerebrum were ordered as subependymal layers of the lateral ventricles, peripheral regions of lateral ventricles in the white matter and some neuron layers under the molecular layer of the gray matter. But NCF were not observed in the cerebellum, pons, medulla oblongata and spinal cords.
2. On the subependymal layers of the lateral ventricles, NCF were observed in 100% of 27 piglets, and appearance decree of +++ was observed ++ in 10 piglets(37.0%), in 10 piglets(37.0%) and + in 7 Piglets(26.0%) of 27 piglets, respectively.
3. On the white matter of the cerebrum, NCF were observed in 25 piglets(92.6%) of 27 piglets, and appearance degree of +++ was observed in 3 piglets(11.1%), ++ in 13 piglets(48.2%), + in 9 piglets(33.3%) and - in 2 piglets(7.4%) of 27 piglets, respectively.
4. On the gray matter of the cerebrum, NCF were observed in 21 piglets(77.8%) of 27 piglets, and appearance degree of +++ was not observed, appearance degree of ++ was observed in piglets(22.2%), + in 15 Pi91e17(55.6%) and - in 6 piglets(22.2%) of 27 Piglets, respectively.
5. NCF tended to be converged appearance on some regions and tended to be decreased markedly from 35th day after birth, and the shapes of NCF were: global or oval forms crowded by analogous shaped and stained cells in the empty spaces of the brain substrate or on one side of the blood vessels.
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