CASOTTI, G.: Microvilli within the lower intestine of sparrows

Tissue from the lower intestine of two species of sparrow, the house sparrow Passer domesticus and savannah sparrow Passerculus sandwichensis was sectioned in an unbiased manner and examined quantitatively using stereology. The tissue was processed for light microscopy, and scanning and transmission electron microscopy to examine the extent to which microvilli enhanced the epithelial surface area of the rectum, coprodeum and cecae. Parameters measured included individual microvillus surface area, microvilli packing density and absolute surface area. In both species, a greater surface area and packing density of microvilli occurred within the rectum and the cecae. Overall, the three measured variables were not statistically significant between species at the 95% confidence level. In the cecae, microvilli within the savannah sparrow had a higher individual surface area, packing density and absolute surface area than in the house sparrow. The functional implications of a change in microvilli population are discussed in relation to retrograde peristalsis within the lower intestine of birds. Funded by a Pennsylvania State System of Higher Education Grant 2112-403.