Abstract
Gastrointestinal segments from 4 healthy, 17-, 21-, 22- and 23-day-old calves fed on whole cow’s milk were examined. Scanning electron microscopy showed that the anterior duodenum had short villi varying in shape from leaf-shaped to nodular; the middle duodenum had broad, tongue-shaped villi and the anterior, middle, and parts of the posterior jejunum had slender, finger-shaped or leaf-shaped villi. The villi of the mucosa covering Peyer’s patches in the posterior jejunum were short and either conical or tongue-shaped; there were also small “pseudovilli” caused by bulges in the lymphoid tissue. Morphometry showed that the villi were longer in the anterior jejunum than in the duodenum and the posterior parts of the jejunum (P < 0.005). Morphologically fat absorption was most heavy in the anterior third of the small intestine. Moderate amounts of fat were also found in the epithelium of the posterior jejunum and of the abomasum. Large fat droplets were seen in apical duodenal enterocytes, in contrast to the small epithelial droplets in other areas with fat absorption. Nile blue staining indicated that the fat in the large droplets was esterified.
Keywords: scanning electron microscopy, intestinal villi, morphometry, fat absorption, milk diet, calves
Sammendrag
Mage-tarmmukosa hos 4 friske kalver 17, 21, 22 og 23 dager gamle, fóret med helmelk, ble undersøkt. Ved skanning elektron-mikroskopi såes i fremre duodenum små villi som varierte fra blad- til knuteformede, i midtre duodenum brede, tungeformede villi og i fremre, midtre og deler av bakre jejunum slanke, finger-, eller bladformede villi. Mukosa over Peyer-plettene i bakre jejunum hadde korte, koniske eller tungeformede villi, og mellom disse såes små “pseudovilli” som var epitelkledte fremhvelvinger av lymfoid vev.
Ved morfometriske undersøkeiser viste det seg at villi i fremre jejunum var lengre enn i duodenum og i bakre avsnitt av jejunum (Ρ < 0,005). Etter morfologien å dømme var fettabsorbsjonen størst i fremre tredjedel av tynntarmen. Moderate mengder fett ble også funnet i epitelet i bakre tynntarm og i løpe. I epitelcellene apikalt i duodenalvilli såes store fettdråper, mens det i andre områder med fettabsorbsjon var små dråper i epitelcellene. Nilblått farging indikerte at fettet i de store dråpene var forestret.
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Footnotes
This study was supported by grants from the Agricultural Research Council of Norway.
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