Cholinesterase-containing nerve fibres on blood vessels in lungs of some laboratory mammals

Summary Distribution of cholinesterase-containing nerve fibres on blood vessels in the lungs of rats, mice, rabbits, guinea pigs, cats, dogs, and rhesus monkeys has been studied with the thiocholine method modified by Coupland and Holmes and with the direct-coloring method according to Karnovsky and Roots. The presence of acetylcholinesterase positive nerve fibres on the pulmonary arteries has been established only in four species of the studied animals, namely the cat, the dog, the rhesus monkey and the rabbit. These nerves form d distinct plexus on the border between the media and adventitia. In the thick walled perihilar branches of the pulmonary artery of the rabbit the nerve fibres penetrate—as a rule—into the outer half of the media. Despite many times repeated experiments and careful investigations no nerve fibres have been found on the intrapulmonary branches of the blood vessels in the lungs of rats, mice, and guinea pigs. In the walls of the pulmonary veins, with the exception of the pulmonary veins in the rat and the mouse, cholinesterase fibres have been identified only seldom. Acetylcholinesterase nerve fibres in medio-adventitial localization have also been found in the walls of bronchial arterioles, this being the case in all the species under study. Bronchial veins do not exhibit any nerve fibres. The distribution of the acetylcholinesterase-containing nerve fibres on the pulmonary arteries is different from species to species.     

Comparative and functional morphology of musculus canalis ani in tetrapod mammals and primates]

Comparative anatomy of structure and function of the M. canalis ani in tetrapode mammals and primates is described for the first time. The muscle itself lies on the sphincter ani internus in the area between the anorectal ("pectinate") and anocutaneal ("white") lines and its circumference is intact around the entire anal canal. The canalis ani muscle orginates from the superior part of the sphincter ani internus and concomitantly receives additional fibers from the longitudinal muscle. Caudally the muscle dips back into the sphincter ani internus and, at the same time, a small portion of the fibers go to the longitudinal muscle and, likewise, a portion also sets itself on the perinaal skin. On the basis of its morphological relationship to the convoluted vessels of the rectal venous plexus, the canalis ani muscle appears to be able to complete the closing of the anus in the continence phase to such an extent that a complete closing of the anal lumen is guaranted.     

Comparative characterization of some enterocytic brush border membrane enzymes in mammals and fish

The properties of the detergent- and protease-forms of alanine aminopeptidase and alkaline phosphatase of enterocytes in rabbits, cows, dogs and trout were investigated. The hydrophobic parts of the enzymes perform not only anchor functions, but also regulatory ones. It is suggested that these functions are of peculiar regularity, but vary in different enzymes of one species as well as in the same enzyme of different species.     

Comparative anatomy of the heart of mammals

Hearts from 20 mammalian orders were examined according to a fixed protocol to determine if the gross differences of shape and internal anatomy could be explained. Three generalizations can be made: firstly differences are most closely related to taxonomic position, secondly some features, such as the prominence of the conus of the right ventricle in animals that leap, dig or sprint regularly as part of their defence mechanism and a long, narrow left ventricle in endurance performers may be more closely related to activity than ancestry, and lastly some characteristics may be pleiotropic effects of thoracic morphogenesis.     

Comparative and functional morphology of the stomach in the adult and newborn pigmy hippopotamus(Choeropsis liberiensis)

Examination of the topographical anatomy of the stomach complex and intestinal tract of an adult male and a newborn female pigmy hippopotamus (Choeropsis liberiensis) shows that the stomach consists of four chambers, the first three constituting the proventriculus and the fourth the glandular stomach. The proventriculus is made up of a visceral and parietal blind sac opening into a connecting chamber, which in turn opens into the glandular compartment. The walls of the proventricular chambers are covered with villi and non-glandular mucous membrane. The significant difference between the animals is that whereas the connecting chamber of the adult stomach lies transversely deep in the cranial part of the abdomen and connects with the glandular chamber on the right side, that of the newborn lies almost vertically and connects ventrally with the glandular compartment situated on the floor of the abdomen. A groove which in the adult runs more or less horizontally from the cardia through the visceral sac and connecting chambers is aligned almost vertically in the newborn. In the adult the connecting chamber is the largest compartment, but in the neonate the visceral blind sac and the glandular compartment are proportionally larger. Functional aspects of these anatomical differences are discussed in relation to suckling behavior. The intestine consists of a continous tube. There is no caecum; instead the junction between small and large intestine is distinguished by an increase in diameter, a change in epithelial lining, and anastomoses of the jejunal and colic arteries. Large amounts of fat are present in the omentum and mesentery of the neonate.     

The architecture of the shoulder in some mammals

A series of nine features of the shoulder girdle, chosen as having functional significance in relation to the movements of the shoulder in arboreal locomotion, have been studied in 1188 specimens of 194 genera of mammals. The features were defined metrically and examined by means of a multivariate statistical technique: viz. canonical analysis. The study has shown that those mammals which are nonarboreal differ considerably among themselves and form the arboreal forms. But the myriad shapes of the shoulder girdle in a wide range of mammals (e.g. some marsupials, edentates, rodents, carnivores and primates) which climb or forage in trees, can be summarized mathematically by a very small number of similar canonical variates. This information correlates well with that of a previous series of studies carried out on the primates alone. The biological information that was postulated as being reflected by the individual canonical variates for the primates is also apparent for the arboreal mammals. The different variates separate the forms in ways which are consonant with what is known about the function of the shoulder in locomotion. Aspects of the shape of the shoulder defined by the analysis appear to be discernible from an examination of the contribution of the original variables to each individual canonical variate. This seems to confirm that the shape of the shoulder girdle within a very wide range of mammals is limited by a very small number of underlying factors of biological significance. One interpretation of the results suggests that the genetic model of the mammalian shoulder may have been sufficiently fixed at an early stage in the evolution of the class as to place considerable constraints upon the subsequent evolution of the shoulder in the different Orders.     

Morphology of the terminal bronchiolar region of common laboratory mammals

The histomorphology of the terminal bronchiolar region of the mouse, rat, hamster, guinea pig, gerbil and rabbit was studied. Although some general structural similarities existed in the progressive intrapulmonary branching pattern of the airway tree between species, there were conflicting accounts in the literature about the presence of the respiratory bronchioles in common laboratory mammals. In our light microscopy study we failed to detect the existence of typical respiratory bronchioles with characteristic interruptions on their walls projecting into the alveoli. Frequently in these species the terminal bronchioles were short and abrupt, opening directly into several alveolar ductules.