Resumo

ARIAS M., Walter; SANDOVAL CH., Nieves; CHAVERA C., Alfonso  e  MANCHEGO S., Alberto. Cytoarchitecture characterization of foetal spleen in the alpaca (lama pacos). Rev. investig. vet. Perú [online]. 2011, vol.22, n.2, pp.81-88. ISSN 1609-9117.

The aim of the present study was to determine the spleen cytoarchitecture in alpaca fetuses of different stages of development. Sixteen alpaca fetuses were obtained from female alpacas slaughtered in the central highlands of Peru. The fetuses were distributed in six groups according to their fetal age (55, 100, 120, 150, 180, and 200 days). Spleens were dissected and samples were stained with hematoxylin-eosin (cellular distribution), Masson´s trichrome (collagen and muscle fibers), and periodic acid Schiff for argentic impregnation (reticular fibers) for histological evaluation. Macroscopically, the spleen at 55 days of age is slightly outlined, at 120 days is lobed with a triangular shape and at 150 days had the appearance of the mature animal. Microscopically, at 55 days there is a predominance of transitional embryonic connective tissue to reticular tissue and some lymphoid cells are located in large vessels, plus cells compatible with hematopoietic nests that are seen in all later stages. At day 100, fibrous connective tissue of the capsule infiltrates the parenchyma to form trabecules and lymphoid cells form lymphoid cumuli that surround the large vessels. At day 120, lymphoid cumuli can be named as white pulp, and the hematopoietic nests become the erythroid series by day 150. At 180 days, lymphoid follicles are filled with lymphocytes resembling mature lymphoid follicles, where the central arteriole is displaced to the surface. Finally, by day 200, the spleen has similar histological appearance of the adult.

Palavras-chave : alpaca; fetuses; spleen; lymphoid groups; hematopoyetic nest.

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