NEB
Nebulin
Publications[править]
In neonatal dogs, neuroepithelial bodies (NEB) are located in the distal lung. They consist of closely packed and granulated epithelial cells showing a positive immune reaction to serotonin and carrying well-developed apical microvilli. They make close contact with capillaries and form morphologically afferent synaptic junctions with intracorpuscular nerve endings. Since most nerve endings degenerate after hilar lung denervation, they are carried by extrinsic, most likely vagal, sensory nerve fibers. We conclude that pulmonary NEB probably are receptor organs, sampling the inspired air and secreting bioactive substances. These might have a local vaso- or bronchoactive regulatory effect, or could be carried to other body parts via the blood vessels. In addition, NEB might induce integrative reflexes via the central nervous system. The NEB intracorpuscular nerve endings also show spontaneous degeneration. This, in addition to the scarcity of NEB in the distal lungs of adult dogs, strongly suggests that the pulmonary NEB are particularly important during the perinatal period of life.
MeSH Terms
- Aging
- Animals
- Animals, Newborn
- Chemoreceptor Cells
- Denervation
- Dogs
- Immunoenzyme Techniques
- Inclusion Bodies
- Lung
- Male
- Microscopy, Electron
- Nerve Degeneration
- Nerve Endings
- Neurosecretory Systems
- Pulmonary Circulation
- Serotonin
- Vagus Nerve
The size, density and total number of neuroepithelial bodies (NEB) in the lungs of late fetal, neonatal, and mature rabbits were determined using fluorescence microscopy. In this study lungs from 27-, 29-, 30-, and 31-day fetuses; neonates of ages 2, 7, and 30 days; and 4- and 7( )-month-old rabbits, were used. The total number of NEB in the entire lung of rabbits from each age group was estimated based on measurements of collapsed lung volume, average NEB diameter, and NEB density (number/mm2). Average NEB diameter increased between 27 and 29 days gestation, then remained constant at 42-44 micron between 29 days gestation and two days postpartum. Thereafter the diameter was significantly reduced in the 7-day group (33.7 micron) and further reduced in the 4-month group (20.3 micron). NEB density was initially high in 27-day fetuses (3.87/mm2), decreased significantly by 30 days gestation, increased to a high level by 2 days postpartum, then fell steadily, reaching the lowest level in the adult (0.15/mm2). This steady decrease in density was paralleled by a large increase in lung volume. The estimated total number of NEB in the lung was constant in all age groups except for a significant drop at 30 and 31 days gestation. These data indicate that the total number of NEB is maintained into adulthood; however, the density and average diameter of NEB decreases rapidly after 2 days postpartum. A sharp decrease in both total number and density observed under fluorescence microscopy at 30 and 31 days gestation suggests a change in NEB cellular activity just prior to birth.
MeSH Terms
- Aging
- Animals
- Female
- Fetus
- Gestational Age
- Lung
- Neurosecretory Systems
- Pregnancy
- Rabbits