| Publication Type: | Journal Article |
| Year of Publication: | 1997 |
| Authors: | A. N. Makanya, Maina, J. N., Mayhew, T. M., Tschanz, S. A., Burri, P. H. |
| Journal: | J. Exp. Biol. |
| Volume: | 200 |
| Pagination: | 2415-2423 |
| Date Published: | 1997 |
| Keywords: | Chiroptera, digestive tract, East Africa, Epomophorus wahlbergi, histology, Kakamega, Kenya, Lissonycteris angolensis, Miniopteridae, Miniopterus inflatus, Nairobi, Naivasha, Pteropodidae, ultrastructure |
| Abstract: | The extents of functional surfaces (villi, microvilli) have been estimated at different longitudinal sites, and in the entire small intestine, for three species of bats belonging to two feeding groups: insect- and fruit-eaters. In all species, surface areas and other structural quantities tended to be greatest at more cranial sites and to decline caudally. The entomophagous bat (Miniopterus inflatus) had a mean body mass (coefficient of variation) of 8.9 g (5%) and a mean intestinal length of 20 cm (6%). The surface area of the basic intestinal tube (primary mucosa) was 9.1 cm-2 (10%) but this was amplified to 48 cm-2 (13%) by villi and to 0.13 m-2 (20%) by microvilli. The total number of microvilli per intestine was 4 times 10-11 (20%). The average microvillus had a diameter of 89 nm (10%), a length of 1.1 mu-m (22%) and a membrane surface area of 0.32 mu-m-2 (31%). In two species of fruit bats (Epomophorus wahlbergi and Lissonycteris angolensis), body masses were greater and intestines longer, the values being 76.0 g (28%) and 76.9 g (4%), and 73 cm (16%) and 72 cm (7%), respectively. Surface areas were also greater, amounting to 76 cm-2 (26%) and 45 cm-2 (8%) for the primary mucosa, 547 cm-2 (29%) and 314 cm-2 (16%) for villi and 2.7 m-2 (23%) and 1.5 m-2 (18%) for microvilli. An increase in the number of microvilli, 33 times 10-11 (19%) and 15 times 10-11 (24%) per intestine, contributed to the more extensive surface area but there were concomitant changes in the dimensions of microvilli. Mean diameters were 94 nm (8%) and III nm (4%), and mean lengths were 2.8 mu-m (12%) and 2.9 mu-m (10%), respectively. Thus, an increase in the surface area of the average microvillus to 0.83 gm-2 (12%) and 1.02 mu-2 (11%) also contributed to the greater total surface area of microvilli. The lifestyle-related differences in total microvillous surface areas persisted when structural quantities were normalised for the differences in body masses. The values for total microvillous surface area were 148 cm-2 g-1 (20%) in the entomophagous bat, 355 cm-2 g-1 (20%) in E. wahlbergi and 192 cm-2 g-1 (17%) in L. angolensis. This was true despite the fact that the insecteater possessed a greater length of intestine per unit of body mass: 22 mm g-1 (8%) versus 9-10 mm g-1 (9-10%) for the fruit-eaters. |