Terminal Swelling Research Articles

A fine structural and enzyme histochemical study of muscle innervation in the normal and 6-hydroxydopamine (6-OHDA)-treated rat vas deferens including a numerical assessment of axonal changes within 48 hours of a single injection of the drug

A distribution study was made of presumptive adrenergic and cholinergic axons in relation to smooth muscle in the vas deferens of the normal and 6-hydroxydopamine-treated rat. Acetylcholinesterase (AChE) was found associated with both types of nerve terminal; cholinergic terminals being AChE-positive and adrenergic terminals AChE-part-positive or AChE-negative. Adrenergic terminals, identified by their content of small (300–500 Å diam.) dense-cored vesicles, were specifically stigmatised by intravital 6-OHDA but up to 48 hr after treatment both degenerate and normal axons could be found. Specific changes in adrenergic terminals induced by 6-OHDA include (1) axon terminal swelling and vacuolation (2) dilatation of many large dense-cored vesicles (3) certain vesicle population changes. No changes were induced in cholinergic terminals by the drug. Comparisons are made with other innervation studies and the results discussed in the light of current theories of adrenergic transmission.

Interference-contrast and phase-contrast microscopy of sporulation in clostridium thermosaccharolyticum grown under strict anaerobiosis.

Cells of Clostridium thermosaccharolyticum grown under strict anaerobiosis (modified Hungate technique) were examined during growth and sporulation by employing Nomarski interference-contrast and Zernike phase-contrast optics to delineate the sequence of morphological changes leading to the formation of free, mature spores. A 0.5% l-arabinose, liquid, complex medium was used to obtain a yield of 30 to 40% free, refractile spores (ca. 10(8)/ml) by 48 hr of incubation. The mean doubling time for the glucose culture (vegetative cells) was found to be 80 min, and that for the l-arabinose culture (sporulating cells), 498 min. By 8 hr of incubation, beginning spore formation became evident in the arabinose culture by the development of a distinct arrowhead-shaped terminal swelling. By 32 hr of incubation or shortly thereafter, Nomarski optics showed the mature spore to be uniformly spherical, whereas the enlarged terminal swelling containing it was not. The use of phase-contrast and interference-contrast optics permitted the characterization of the distinctive morphological changes occurring during sporulation of C. thermosaccharolyticum.

Centriole migration

Centrioles were observed in varying stages of migration in bipolar sensing cells from domestic rabbit, wild rabbit, dog, and cat olfactory epithelia. The centrioles were seen in their normal juxtapositions with the nuclei and the basal bodies and also throughout the length of the narrow dendritic processes. Dendrites that contain centrioles have few mitochondria present. The evidence suggests that the centrioles reduplicate in the cell body and then migrate to the terminal swelling for ciliogenesis. We conclude that centriole reduplication and migration are necessary processes in cilia replacement and possibly in new cell development and cell regeneration throughout the life of the animal.

West Indian Species of Asterostroma, with Notes on Extralimital Species

Three species of Asterostroma, A. andinum Pat., A. cervi- color (Berk. & Curt.) Massee, and A. musicolum (Berk. & Curt.) Massee occur in the West Indies. These species are analyzed morphologically and the development of the asterosetae and basidia is described. Com- ments on extralimital species are presented, along with morphological notes. The' genus Asterostroma was established by Massee in 1889 for certain corticioid basidiomycetous fungi with asterosetae. The genus is based on Corticium apalum Berk. & Br. (see Donk, 1957b). About 21 taxa have been described for Asterostroma, but about five of these have been relegated to synonymy. The latest comprehensive treatment of North American Thelephoraceae (Burt, 1924) lists six species, but Rcgers and Jackso,n (1943) reduced three of these (A. bicolor Ell. & Everh., A. gracile Burt, A. spiniferum Burt) to synonymy as variants of A. andinum Pat., and synonymnized A. ochrostroma Burt with Asterodon ferruginosum Pat. The remaining three species were all listed by Burt as occurring in the West Indies. Asterostroma is characterized by effused basidiocarps spreading either continuously or in an interrupted manner over the stubstrate. The basidiocarps atre dry, and the smooth hymenial sLurface, espe- cially in thin forms, is pierced by reddish-brown aster'osetae. In tex- ture, the basidiocarps vary from arachnoid, byssoid, pellicular, to spongy-crustose depending upon the degree of hyphal development. The basidiocarp is white to buff in color, but the coloring is greatly modified by the' degree, of development of the astercsetae and their penetration o,f the hymenial surface. Around the extreme margins the hyaline hyphae have a whitish appearance; towards, the' center a reddish-brown color develops due to the asterosetae. In sections, the basidiocarps are composed of strands of loosely interwoven, unexpanded, branching, hyaline hyphae without clamp- connections or conspicuously thickened walls. These, hyphae give rise to the characteristic, thickened asterosetae. Asterosetal development begins as a terminal swelling of an undifferentiated hypha and from this swelling arise the arms of the asteroseta (Fig. 1, C). In A. andinum Pat. that arm which develops on the hymenial side often is the longest and most well developed (Fig. 1, A), but this feature is not a constant one for that species. Corner (1948) has shown that if an asteroseta develops within a hymenial region, variolus kinds, of asymmetry result. Such asymmetry in A. andinumn can be correlated in our specimens with thin fructifications. In A. cervicolor (Berk. &

Transport of oxidative enzymes in nerve fibers; A histochemical investigation of the regenerative cycle in neurons

Histochemical investigations have been performed on the behavior of succinic dehydrogenase, diphosphopyridine nucleotide (DPN) diaphorase, and triphosphopyridine nucleotide (TPN) diaphorase during the regenerative cycle of neurons following axonal interruption. Changes in enzyme distribution were observed both in the sciatic nerve of rats and in central descending tracts of the cat. Chromatolysis of nerve cells was accompanied by a depletion of certain enzymes in the cell body and a transport of these enzymes along the axons with their accumulation in the terminal swelling at the site of interruption. No enzymes were found in the distal disconnected part of the axon. That the enzymes truly propagated along the axons was proved by their damming proximal to a ligature tied tightly about the sciatic nerve. If the nerve was cut distal to the ligature, no enzymes accumulated at the site of interruption. The changes in enzyme distribution were most pronounced for succinic dehydrogenase and TPN diaphorase. The differences in the behavior of the individual oxidative enzymes studied suggests that two different reactions occur following axonal interruption: a damming of a normal propagation of enzymes along the axon, which occurs for all three enzymes, and an additional reaction of increased enzyme transport, which differs in intensity for the individual enzymes (Fig. 1). During degeneration of transected peripheral nerves, changes also occurred in the enzyme distribution within neurilemma cells. These changes appeared independent of the redistribution of the enzymes within neurons. The fragmentation of myelin was accompanied by an increased activity of all three enzymes in the cytoplasm of neurilemma cells. Aside from this behavior during degeneration, striking differences were observed in the distribution of the individual enzymes in normal neurilemma cells.

Elektronenmicroscopische waarnemingen over de zoösporen uit de zomersporangia vanSynchytrium endobioticum (Schilb.) Perc

Electron microscope observations on the soral zoospores ofSynchytrium endobioticum revealed, besides nuclear substance, the presence of a crateriform cavity in the zoospore body. Probably this cavity corresponds with the vacuole which contains oil in the living zoospore. The flagella are cylindrical and they have a whiplash tip. Faint longitudinal striations can just be detected in some of the flagella. A slight terminal swelling on the end of the whiplash is occasionally found. Several flagella, showed fibrillar disintegration. Making elevent fibres in all, there are two long central strands and nine shorter peripheral strads. A fine line running along the centre of some fibres indicates that probably each fibre contains two subfibres.