Evidence for a periaqueductal gray-nucleus retroambiguus-spinal cord pathway in the rat.

The nucleus retroambiguus in the cat has been shown to receive strong projections from the periaqueductal gray and to send fibres to distinct motoneuronal cell groups in brainstem and spinal cord. The nucleus retroambiguus plays a role in the production of vocalization and possibly copulatory (lordosis and mounting) behaviour. The question arises of whether a periaqueductal gray nucleus retroambiguus-spinal cord projection also exists in the rat.

Dorsal border periaqueductal gray neurons project to the area directly adjacent to the central canal ependyma of the C4-T8 spinal cord in the cat.

In a previous study horseradish peroxidase (HRP) injections in the upper thoracic and cervical spinal cord revealed some faintly labeled small neurons at the dorsal border of the periaqueductal gray (PAG). The present light microscopic and electronmicroscopic tracing study describes the precise location of these dorsal border PAG-spinal neurons and their terminal organization. Wheat germ agglutinin-conjugated HRP (WGA-HRP) injections into cervical and upper thoracic spinal segments resulted in several hundreds of small retrogradely labeled neurons at the dorsal border of the ipsilateral caudal PAG.

Density of eosinophils reflects activity of disease in allergic asthmatic children.

Background: Low density eosinophils are more prominent in asthmatic patients compared with healthy subjects. LDE are metabolically more active and produce more tissue-injuring and spasmogenic proteins than normal eosinophils.

Objective And Methods: With a method providing information about eosinophils of 12 different densities we were able to study eosinophil density characteristics in 24 young patients in detail with allergic asthma in a stable phase, and in 21 patients after a bronchial allergen challenge.