Direct transdifferentiation: can cells change their phenotype without dividing?
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Animals↗
Biomedical subjects
W A Beresford
Publications and source records attributed to W A Beresford.
Is it coincidence that iron and melanin coexist in hepatic and other melanomacrophages?
Use of a Prussian-blue histochemical method shows iron in some but not all hepatic melanomacrophages of turtle, alligator, caiman and anole. The hypothesis prompted is that melanomacrophages in general synthesize melanin to render less noxious free radicals arising from catalysis by the iron.
Alligators and Crocodiles↗
The aging intervertebral disk.
This paper outlines the structure of the intervertebral disk and the process by which altered cellular mechanisms lead to deterioration with age. A reference list indicates current trends in research that attempt to explain the changing nature of the intervertebral disk and its role in spinal disease.
Aging↗
The penile bone and anterior process of the rat in scanning electron microscopy.
The penile bone and anterior process were made anorganic for scanning electron microscopy. The mature bone has a basal bulb and a long, cylindrical shaft bevelled at its tip to fit under a matching surface on the anterior process, giving rise to a bevelled 'suture'. A rough, resting, Sharpey-fibre bone surface covers the base and tip of the bone, the dorsal crest along the shaft, and parts of the lateral and ventral surfaces. The penile bone grows by endochondrial ossification at its basal end, but the cartilage cells are randomly disposed and not arranged in columns as in most 'long' bones. The growing bone, at 8 weeks, shows evidence of resorption externally where the base 'waists in' to the shaft: the corresponding endosteal surface within the basal bulb is formative, in accordance with the 'V-principle' of remodelling. It is concluded that the anterior process, penile bone and proximal erectile body (corpus cavernosum) form a firm, tightly fastened, articulating chain, perhaps serving to aid penetration.
Aging↗
Intracerebral transplantation of the genital tubercle in the rat: the fate of the penile bone and cartilages.
Genital tubercles of 70 newborn male and female rats were transplated into the brains of unrelated infant rats. Seven other tubercles were placed subcutaneously. All female, and some male, hosts were injected with testosterone propionate. After surviving from 2-24 days,, histological study of 49 successful grafts showed survival of the urethral and balano-preputial epithelia and growth of the preputial glands, which formed secretion-filled cysts and became the major component of the graft. The fate of the mesodermal tissues witin the glands varied between remaining in an undeveloped state, with only pale fibrouw tissue and an area of granular degeneration and giant cells, and achieving an incompletely differentiatel state in which erectile tissue and the anterior process of fibrocartilage had formed and the glans had grown but the penile bone and its secondary growth cartilage failed to appear. Grafts could reach this degree of differentiation of the glands irrespective of transplantation site, attachment to the host dura, the sex of donor or host, and whether or not male hosts were given exogenous hormone.
Animals↗
Schemes of zonation in the mandibular condyle.
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Animals↗