Morphometric characteristics of the small and large intestines of Mus musculus during postnatal development.

The objective of this study was to investigate the size of the small and large intestine in postnatal development of Mus musculus mice. The gut was obtained from 2-, 4-, 6-, and 12-week-old animals. The morphometric analysis was performed at microscopic level. Measurements and calculations included dimensions of villi (height, diameter) and their number per 1 mm(2) surface area in the proximal, middle, and distal section of the small intestine, as well as the length and surface area (external and internal) of the small and large intestines. To find the allometric relationship between the size of the small and large intestines and body mass, reduced major axis regression was applied. The length and surface area of both intestinal segments gradually increased with age. The increase in the internal surface area of the small intestine was the result of lengthening of the intestine and increasing diameter of the villi in its proximal and middle sections. No increase in villus height during the studied period was detected. A marked increase in the size of the intestinal segments was observed between the 2(nd) and 4(th) weeks of life, when the length doubled and the surface area tripled in size. Allometric analysis revealed that the increase in length and internal surface area of the small and large intestines was more rapid than the body mass increase during the weaning period, while it was not different from isometry after the weaning. In conclusion, the greatest changes in the structure and size of the small and large intestines of mice occurred in the weaning period. During this period these two segments of intestine grew faster than the rest of the body and reached adult proportions.

Morphological analysis of the functional design of the connection between the alimentary tract and the gas bladder in air-breathing lepisosteid fish.

There is considerable controversy in the literature regarding the existence of a "longitudinal slit" versus a "duct" connecting the respiratory gas bladder with the alimentary tract in various species of garfishes (Lepisosteidae). The aim of the present work has been to address these discrepancies on the basis of our own work on longnose gar Lepisosteus osseus in conjunction with a review of the literature. We provide anatomical evidence for a better understanding of the functional advantages of the "longitudinal slit" versus the "duct" in respect to feeding and respiration in juveniles longnose gar. The anterior part of the garfish body cavity, from the oral cavity to the stomach, was used for morphological and histological analysis. It has been observed that the air bladder in the longnose gar is open to the alimentary tract through a longitudinal slit which is present in the glottis on the dorsal side of the oesophagus. The external side of the glottal ridges in the anterior oesophagus, on the side of the opening, consist of stratified squamous epithelium which then turns into the pseudostratified columnar ciliated epithelium in the posterior oesophagus. The glottal ridges are comprised of epithelia and radially arranged striated muscle fibres surrounded by connective tissue. It can be surmised that the tunica muscularis in the anterior oesophagus of garfish aids the glottis in moving air in and out because it supports the dorsal retractor muscle in propelling air through the longitudinal slit from the buccal cavity. When the buccal cavity of the garfish is contracted during holding prey, the muscles of the gas bladder wall and tunica muscularis, located inside and outside the glottal ridge, participate in exhalation.

scanning electron microscopy of lingual papillae in the common shrew, Sorex araneus, L.

The dorsal surface of the tongue of the adult common shrew (Sorex araneus L.) was examined by scanning electron microscopy. As in the other insectivores, three types of lingual papillae were observed: filiform, fungiform and vallate papillae. The filiform papillae represented the most numerous type of lingual papillae. The characteristic feature of the filiform papillae, covering the apex and corpus of the tongue, is the two processes tilted to the root of the tongue. The filiform papillae on the lingual apex are reduced in size and structure. Five to six fungiform papillae are placed symmetrically along the left and right border of the corpus of the tongue. Two large oval vallate papillae are located on the radix of the tongue. The posterior surface of the tongue in common shrew is covered with a smooth mucosa with the openings of the serous glands.