Estudio comparativo de la organización estructural y funcional de la pineal en la especie ovina.

Resumo

This Doctoral Dissertation deals with some aspects of the ovine pineal gland. The studies were done on a total of 60 healthy animals, of several races and ages. The investigations were carried out as follows: Light microscope study in order to know the differences between animals slaughtered in the day period and at night, as well as between young and adult individuals. Morfometric study of nuclei of pinealocytes of young animals, to find out the modifications in the nuclear size according to the photophase and the zone of the gland (cortical / medular). Electron microscope study of the different synaptic bodies of the pineal gland in young animals, related to photophase. We have found the following results. Ovine pineal gland is, as well as the human one, of A type. The parenchyma presents two clearly differentiated zones: cortical and medular. Mature astrocytes which are vimentine positive and glial fibrillary acidic protein (GFAP) positive are observed in the whole gland, and at all ages, whereas in rat are only located in the proximal part of the gland. The endotelial cells are vimentine positive and GFAP negative. In old animals are more cysts, conective tissue and positive cells to vimentine and, mainly more cells GFAP positive. The nuclei of pinealocytes are 15'49% bigger in the animals slaughtered by day than at night. These differences are statistically significant. The number of synaptic bodies is inferior in the day group (9'95±3'77) than in the night one (18'75±3'83). In the day period, synaptic ribbons are 31'25% of the synaptic bodies, 33'03% are synaptic spherules, and the intermediate forms are 35'71%. In the night period, synaptic ribbons diminish and only represent the 8'53% of synaptic bodies, while 64'93% are intermediate forms, and synaptic sperules are 26'54%. In the day period there aren¿t ovoid intermediate forms, whereas in the night period they represent the 14'69% . According to the previous data we conclude that the ovine pineal gland has a different activity deppending on the photophase.