Cholinergic nerves in the lacrimal gland of the desert rat.

The histochemical localization of acetylcholinesterase activity in the lacrimal gland was investigated in intact (control) and chemically sympathectomized desert rats. An intensely positive specific cholinesterase reaction was found in the thick nerve bundles distributed throughout the interlobular connective tissue septa. Thick and fine nerves were present in the vicinity of the intra- and interlobular ducts and round the glandular acini and the blood vessels. The finding that this distribution pattern did not alter in the lacrimal gland of chemically sympathectomized animals suggest that the nerves are of a parasympathetic nature.

Reappraisal of age-related morphological changes in the rat thymus--morphometric study.

A quantitative morphometric study, using a routine histological technique, was carried out with 72 rats aged 7 and 15 days, 1, 4 and 9 months and 1 1/2 years. A micrometric eyepiece, calibrated by means of a stage micrometer, was employed for measurement. Change due to aging included loss of septa, increased fatty infiltration, diminished demarcation of the cortex from the medulla and a decrease in the number of Hassall's corpuscles. The thymus of rats aged 1-4 months was considered to be active; it had well-developed septa, the largest lobules, with complete demarcation of the cortex and medulla, and the maximum number of Hassall's corpuscles. Differences between some of these parameters in males and females were observed.

Cholinergic innervation of the cornea and iris of the guinea pig.

Cholinergic innervation of the cornea and iris of the newborn and adult guinea pig was studied by the technique of Karnovsky and Roots (1964). The given structures are both richly innervated. The cholinesterase reaction of the cornea is more strongly positive in adult animals, whereas the intensity of the reaction of the iris in newborn and adult guinea pigs is almost identical.

Innervation and cholinesterase activity in the skin of albino and desert rats.

The distribution of nerves and cholinesterase activity in the skin of the desert and albino rats has been studied using both histological and histochemical techniques. In the desert rat, the skin was richly innervated. Specific cholinesterase was concentrated in the nervous network of the dermis and around the hair follicles, in the nerve bundles of the dermis, in perivascular nerves, in fine intra-epithelial nerves and in sensory end organs in the junctional area between the dermis and epidermis. In the albino rat, specific cholinesterase was concentrated in the sebaceous glands. The positive cholinesterase activity that was seen in the desert rat in intra-epithelial nerves, and in dermal and hair follicle networks could not be demonstrated.

Succinic dehydrogenase and cholinesterase activities in the skeletal muscles of the desert rat and the albino rat.

The deltoid and gluteus maximus of the desert rat and the albino rat were examined histochemically for the distribution of succinic dehydrogenase (SDH) and cholinesterase (ChE). SDH activity showed that the deltoid and gluteus maximus muscles of the two animals consisted of three types of muscle fibres, with a predominance of muscle fibres that have higher SDH activity in both the deltoid and gluteus maximus muscles of the desert rat than in the albino rat. The mean diameter of all muscle fibres in the deltoid and gluteus maximus muscles and their ratios to the average body weight were determined in both animals. The desert rat showed a statistically significant increase in those ratios compared with the corresponding ratios for the albino rat. ChE activity showed that the deltoid and gluteus maximus muscles are richly innervated by intensely positive ChE motor end-plates with a predominance of plaque-like terminals. The mean diameters of the end-plates and the ratios of these diameters to the diameter of the muscle fibres together with their ratios to the body weight were determined. A correlation between these values and the histological findings is proposed.

Changes in cholinergic and noradrenergic nerves in the pregnant and postpartum uterus of the albino rat and guinea pig.

The present study was undertaken to investigate the structural changes in both cholinesterase (ChE)-positive nerve fibers and adrenergic nerves with formaldehyde-induced fluorescence in pregnant and postpartum uteri of both the albino rat and guinea pig. Particular attention was directed to the relationship between these changes and the local factors associated with the growing fetus. ChE reaction was absent in the control and pregnant uterus of the guinea pig. In the albino rat, there were signs of degeneration in pregnancy. These were evidenced by vacuolation of large nerve trunks and the presence of focal segments with very faint reaction along the course of the nerve bundles. Myometrial segments from fetus-containing horns showed some fragmented nerve fibers, but at the same time some other normal ones. Most of the fine nerve bundles gave a weak reaction. Three weeks after delivery, multiple ChE fibers were found in the uterus of the albino rat. The normal appearance was, however, not regained and some nerve fibers were still fragmented. Noradrenergic (NA) nerve fibers were disintegrated and markedly reduced in number in the myometrium of the pregnant uterus of both the guinea pig and albino rat, particularly in the uterine horns that were distended by fetuses. The number of NA fibers was not significantly reduced in the tubal ends of the albino rat uterus. Three weeks after delivery, normal NA fibers were seen in the myometrium of both the albino rat and guinea pig uterus. Nerves with reduced fluorescence reaction were observed less frequently.

Comparative histological and histochemical studies on the adrenal gland of the albino and the Egyptian desert rats.

The adrenal gland of the albino rat and the Egyptian desert rodents Gerbillus pyramidum and Gerbillus gerbillus was subject to histological and histochemical studies. Compared to the albino rat, the adrenal gland of the Egyptian desert rat had a thicker capsule, its zona glomerulosa was thinner and more vacuolated, its cortex was sharply demarcated from the medulla which appeared in the form of packets of cells. Lipid droplets were larger and more numerous in the zona glomerulosa and no subglomerular zone was detected. Cholesterol and its esters were less marked in the outer cortex. Succinic dehydrogenase activity was more marked in the zona reticularis. The cholinesterase-reactive nervous network in the medulla was more complex and dense and the nerve cells were fewer. The significance of these differences is discussed.