A histochemical study on the innervation of the cerebral blood vessels in the carp

Pericyte endothelial gap junctions in human cerebral capillaries

Human cerebral tissue has been ultrastructurally studied and gap junctions have been visualized between endothelial cells and pericytes that permit ion exchange. We propose that the functional interrelationship between endothelium and pericytes may play a role in the alteration of capillary diameter for the control of local cerebral blood flow.

A histochemical study on the innervation of the cerebral blood vessels in bats

The adrenergic and cholinergic nerves innervating the cerebral blood vessels of four species of Japanese chiropterids (Rhinolophus ferrumequinum, Murina leucogaster, Vespertilio superans and Miniopterus schreibersi) have been investigated using specific histochemical techniques. In all these species of bats arteries of the internal carotid system are poorly developed, whereas those of the vertebro-basilar system are well developed. The adrenergic and cholinergic nerves innervating these cerebral arteries, however, all originate from the stem nerve bundles entering the cranial cavity along the internal carotid artery. Both nerve plexuses are among the densest of any vertebrate species so far investigated. Adrenergic nerve plexuses are usually composed of complicated meshworks of fine fibres, while cholinergic ones are composed of rather longitudinally arranging meshworks of both thick and thin fibres, exhibiting a very high acetylcholinesterase activity. Small parenchymal arteries and arterioles are also dually innervated by adrenergic and cholinergic nerve fibres of peripheral origin. Intracerebral capillaries, on the other hand, are in several places directly connected with both adrenergic and cholinergic fibres of parenchymal origin. Capillaries in the cerebral and cerebellar cortices, diencephalon and cochlear nucleus in v. superans exhibit a heavy non-nervous acetylcholinesterase activity in their walls, but in R. ferrumequinum and M. schreibersi, the response is weak or negative, except for that in the cochlear nucleus.

A histochemical and ultrastructural study of serotonin-containing nerves in cerebral blood vessels of the lamprey

Lamprey, Entosphenus japonicus, cerebral blood vessel autonomic nerve supply was studied with fluorescence and cholinesterase histochemistry and electron microscopy. Nerve fibers emitting a yellow fluorescence characteristic of serotonin (Exc./Em. max.; 380/530 nm) were found on the major cerebral and pial arteries, but not acetylcholinesterase (AChE)-positive ones. Single ganglion cells also emitting a strong yellow fluorescence were seen in the artery adventitia. On rare occasions these cells were observed in pairs. Terminal varicosities of central catecholamine-containing nerves (Exc./Em. max.; 410/475 nm) were observed on parenchymal capillaries, but not central AChE-positive nerve terminals. In ganglion cells, dense cored vesicles (ca. 130 nm in average diameter; DCV) were abundant in the Golgi area, suggesting their formation at this site. Two types of DCV were observed; one with a homogeneous dense core and the other with a granular core. DCV were numerous in axons as well, axons in which many small clear vesicles (40--60 nm in diameter) as well as DCV were occasionally observed. The question of whether the small clear vesicles or the DCV contained serotonin could not be resolved.