The development of Wistar rat fundic glands was studied using Griffonia simplicifolia agglutinin-IB₄ (GSA-IB₄) at the light microscopic and electron microscopic levels.
In adult rats, GSA-IB₄ specifically labeled the intracellular canaliculi and the apical surface on the fundic gland parietal cells, whereas the other sites of these cells were very weakly or rarely labeled.
Ontogenic studies revealed that at 18 days of gestation, GSA-IB₄ positive reaction was found along the whole cell surface of the cells on the fundic gland and immature intracellular canaliculi of the primitive parietal cells. At 1 day after birth, the positive reaction was restricted to the parietal cells. GSA-IB₄ specifically labeled the intracellular canaliculi and the apical cell surface of the parietal cells, but the labeling of the basolateral cell membrane of parietal cells decreased. At the point of weaning, 3 weeks after birth, GSA-IB₄ strongly labeled the intracellular canaliculi whereas the basolateral membrane was weakly labeled. This staining pattern did not change basically until adult stage.
From these results, it is concluded that the functional maturation of the parietal cells may occur at weaning in spite of their early appearance of morphological characters.