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H J Gamble

Publications and source records attributed to H J Gamble.

7 recordsLinked to original sources
PubMed1979

An electron microscopic study of the pericytes of the developing capillaries in human fetal brain and muscle.

Capillaries of the developing cerebral cortex were examined by electron microscopy and compared with those developing in the superior rectus oculi muscle. The pericytes of cerebral vessels were found to be of very elaborate form and involved in complex 'peg and socket' relationships with endothelial cells. They were numerous and formed an almost complete investment of the endothelium. In the muscle, by contrast, pericytes were rare, although often of complex form. Cerebral capillaries were always completely and closely invested by neuropil, in marked contrast to the very loose connective tissues in the vicinity of muscle capillaries. The significance of the findings is discussed.

Brain↗
PubMed1979

Changes in axonal numbers in developing human trochlear nerve.

Complete axonal counts have been made in the intracranial parts of trochlear nerves from human fetuses of 9.2, 10 and 24 cm crown-rump length. A count was also made in the intraorbital part of the nerve from the 10 cm specimen. Schwann cell nuclei were also counted in typical cross sections, but do not necessarily reflect very accurately the schwann cell contents of the nerves. Axonal numbers conform to the propositions (1) that they do not all grow out at once, (2) do not all survive and (3) that degeneration may occur before or after myelination has begun. It seems inevitable that some loss of Schwann cells occurs in relation to the degeneration of myelinated axons, but there is no evidence for or against such a loss in relation to the degeneration of unmyelinated axons. Overall, however, Schwann cell numbers tend to increase as the number of myelinated axons increases.

Axons↗
PubMed1979

Light and electron microscopic observations on the development of the blood vascular system of the human brain.

The development of the blood vascular system of the human fetal brain was examined by both light and electron microscopy. By light microscopy the brains of human embryos and fetuses ranging in size from 8.5 to 70 mm crown-rump length have been studied in serial sections, usually of the whole embryo or fetus. In the smallest specimens the whole brain was encapsulated by a very dense vascular plexus. From this, perforating offshoots passed to or from the substance of the brain, while other connexions were effected with neighbouring arterial and venous channels. These latter vessels were never more mature than capillaries, and their status only recognizable by their location and ultimately by their connexions with the heart. The neopallial part of the cerebral hemisphere was later than all other parts of the brain in receiving vessels perforating its substances. There is some evidence, however, that the cellular basis of a blood vascular supply was present in this part of the brain before lumina and blood cells appeared. The cerebral cortex of fetuses ranging from 50 to 100 mm crown-rump length was examined. Both the extrinsic and intrinsic vessels of the cortex were never more mature than capillaries; occasionally a capillary was seen to penetrate the cortex from the surrounding pial investment. Within the developing cerebral cortex blind ending solid endothelial sprouts were identified, as well as 'seamless' capillaries.

Arteries↗
PubMed1978

Electron microscope observations on human fetal striated muscle.

The superior rectus oculi muscle from human fetuses of 5, 9.2, 12 and 24 cm crown--rump length (of ages estimated to be 10, 12, 15 and 23 weeks respectively) have been examined by electron microscopy. "Myotube satellite cells" closely associated with myotubes and myocytes were present in all specimens, but their relative numbers declined with advancing age. Some were small with scanty cytoplasm containing few organelles. Others were rich in organelles, including Golgi apparatus, granular endoplasmic reticulum, comma and dumb-bell shaped dense bodies and centriole or basal body: these cells were numerous in the three smaller specimens but almost absent from the largest. Seemingly active "myotube satellite cells" often extended cytoplasmic processes beyond their confining basal laminae into the endomysial space to contact freelying cells of similar appearance, as well as axon-associated Schwann cells, often to form an extensive network. These "myotube satellite cells" resembled Schwann cells in all respects save association with axons, and it is suggested that they are, indeed, Schwann cells so disposed as to promote axonal growth towards differentiating, but as yet uninnervated, myocytes. Neuromuscular contacts were increasingly numerous with advancing age, usually where several or many axonal terminals contacted a relatively mature (myofilament-rich) muscle cell. Immature myotubes seldom made contact with axonal terminals, even when a closely adjacent (and "coupled") mature muscle cell did so. A sequence of axonal growth and retraction has been proposed which reconciles accounts of early but temporary polyneuronal innervation with commonly accepted ideas regarding the scattered distribution of the muscle components of motor units.

Gestational Age↗
PubMed1978

Observations on the development of the connective tissues of developing human nerve.

Trochlear nerves from two human fetuses, and digital nerves from a third, have been examined by electron microscopy. Very marked differences in maturation were found between trochlear nerves of fetuses of ages differing only by 2--3 weeks, and between proximal and distal parts of the same trochlear nerve. Immaturity was reflected in paucity of endoneurial space and collagen and in the rarity, or virtual absence, of endoneurial fibroblasts. Circumstantial evidence of collagen formation by Schwann cells has been presented and discussed.

Axons↗
PubMed1978

Electron microscope observations on the changing relationships between unmyelinated axons and Schwann cells in human fetal nerves.

The superior rectus oculi muscle from human fetuses of 5, 9.2, 12 and 24 cm crown-rump length (equivalent to 10, 12, 15 and 23 weeks respectively) and a finger from a 9.5 cm crown-rump length (12 weeks) human fetus were examined by electron microscopy. Very simple relationships between Schwann cells and large bundles of axons were found in the superior rectus muscle of the 5 cm fetus and in the large nerve bundles of the fetal finger. Absence of collagen fibrils in the vicinity of these nerve bundles was also noted. In the superior rectus muscles of the older fetuses the complexity of the Schwann cell/axon relationship increased dramatically, the effect being to envelop single axons in Schwann cell processes. This was also the case in the smaller elaborate bundles in the fetal finger which lay adjacent to move primitive, simply invested nerve bundles. In the examination of near serial sections of Schwann cell/axon bundles it was found that the Schwann cell processes, originally likened to a curtain hanging in fluted folds and slightly twisted, was also badly torn and tattered into longitudinal strips of uneven length. In near serial sections, dramatic changes have been found in the arrangements of Schwann cells and axons. Axons may be singled out and separately invested by the Schwann cell processes, but only for short distances. Lateral transfer of axons from one nerve bundle to another may occur, and loss of axons is apparently not uncommon. The same axon may be of very different diameters at different points along its length.

Axons↗