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Biomedical subjects

M L Lucchi

Publications and source records attributed to M L Lucchi.

At least 37 records · Page 2Linked to original sources
PubMed1990

Simultaneous cell death in the trigeminal ganglion and in ganglion neurons present in the oculomotor nerve of the bovine fetus.

A well-developed ganglion and scattered ganglion cells are present in the intracranial portion of the oculomotor nerve during the first half of fetal life in the ox. In the second half of fetal life a dramatic reduction of the ganglion cells associated with the oculomotor nerve occurs because of spontaneous cell death. Concomitantly, the same phenomenon of cell death is found in the trigeminal ganglion, especially in its rostromedial portion. Free degenerating perikarya can be found in the cavernous sinus.

Animals↗
PubMed1989

Different intrafusal fiber composition of spindles in sheep and pig extraocular muscles.

Histochemical profiles of intrafusal fibers have been examined in muscle spindles of extraocular muscles of sheep and pig. Results show that in the sheep the intrafusal content presents, in addition to chain fibers, at least one bag1 and one bag2 fiber, whereas in the pig almost all the spindles are one-bag-fiber [corrected] spindles.

Adenosine Triphosphatases↗
PubMed1989

On the nature of the afferent fibers of oculomotor nerve.

The oculogyric nerves contain afferent fibers originating from the ophthalmic territory, the somata of which are located in the ipsilateral semilunar ganglion. These primary sensory neurons project to the Subnucleus Gelatinosus of the Nucleus Caudalis Trigemini, where they make presynaptic contact with the central endings of the primary trigeminal afferents running in the fifth cranial nerve. After complete section of the trigeminal root, the antidromic volleys elicited in the trunk of the third cranial nerve by stimulating SG of NCT consisted of two waves belonging to the A delta and C groups. The area of both components of the antidromic volleys decreased both after bradykinin and hystamine injection into the corresponding cutaneous region and after thermic stimulation of the ipsilateral trigeminal ophthalmic territory. The reduction of such potentials can be explained in terms of collision between the antidromic volleys and those elicited orthodromically by chemical and thermic stimulation. Also, capsaicin applied on the nerve induced an immediate increase, followed by a long lasting decrease, of orthodromic evoked response area. These findings bring further support to the nociceptive nature of the afferent fibers running into the oculomotor nerve.

Animals↗
PubMed1989

The fine structure of the area postrema of the sheep.

The ultrastructural features of the area postrema (AP) were investigated in the suckling lamb, weaned lamb and adult sheep. No morphological differences were observed between lambs and sheep. Unciliated ependymal cells, linked by zonulae adherentes-type junctions and gap junctions, cover the AP ventricular surface. Clusters of pyriform neurons, glial cells, and axons are present in the parenchyma. The blood vessels are surrounded by wide perivascular spaces, which present an inner and outer basal lamina. The capillaries are of the fenestrated type. Perivascular glial cells rest on the outer basal lamina of the perivascular space and form a continuous ensheathment with their cell bodies or with flattened interdigitating processes. Along adjacent perivascular glial processes gap junctions are present. From our ultrastructural observations it appears that the overall cellular morphology of AP of the sheep does not differ substantially from that of monogastric mammals.

Aging↗
PubMed1988

Fiber sizes and histochemical characteristics of the rectus abdominis muscle of the rabbit under conditions of pregnancy and mechanically induced stress.

Histochemical properties and muscle fiber diameters of the rectus abdominis (RA) muscle of the female rabbit were compared with those of RA muscle of (1) pregnant females at term of pregnancy (30 days); (2) pregnant females in which the stretch on the abdominal wall natural to pregnancy was artificially prolonged with a 40-day period of intraabdominal appliance; (3) virgin females subjected to intraabdominal appliance for 30, 45, 60, and 70 days. The RA muscle of the control female rabbits is composed of 29.73% type I, 12.13% type IIA, 57.59% type IIB, and 0.54% type IIC fibers. The stimulation on RA muscle due to either normal pregnancy or implant in virgin females provoked changes in muscle fiber diameters only; with the normal pregnancy plus the subsequent period of mechanical stimulation, changes occurred not only in muscle fiber diameters, but there was also a significant increase in the percentage of type I fibers and a concomitant decrease of type IIA and IIB fibers. The fiber-type pattern in the RA muscle of male and female rabbit also was compared. The RA muscle of the male rabbit showed more type IIA and less type IIB fibers than found in that of the female. Type I fibers were larger in the female, but type IIA fibers were larger in the male. In addition, male rabbits also were subjected to 30, 45, 60, and 70 days of RA muscle stimulation by means of an intraabdominal appliance to ascertain if the influence of such stimulation upon the RA muscle differed between the two sexes. Some differences in the response of the male RA muscle were noted.

Abdominal Muscles↗
PubMed1987

Histochemical types and sizes of fibers in the rectus abdominis muscle of guinea pig: adaptive response to pregnancy.

Effects of pregnancy stimulation upon histochemically assessed myofibrillar ATPase and muscle fiber diameters were analysed in the rectus abdominis (RA) muscle of guinea pig. Samples of the muscle were taken at 30, 40, 50, 60, and 70 days of pregnancy and compared with samples of the same muscle taken from nonpregnant guinea pigs. Changes in muscle fiber proportions were noted through the course of pregnancy. Starting from 50 days of gestation an increase in type I fibers and a decrease in type IIB fibers were noted. Increase in muscle fiber diameters was also observed in type I, IIA, and IIB fibers. In addition, the RA muscle of the male guinea pig was compared with that of the female guinea pig and showed more type IIA and less type IIB fibers and all the three fiber types were larger than those of the female.

Abdominal Muscles↗
PubMed1987

Influence of oculomotor nerve afferents on central endings of primary trigeminal fibers.

Painful fibers running in the third nerve and originating from the ophthalmic trigeminal area send their central projections at level of substantia gelatinosa of nucleus caudalis trigemini. The central endings of these fibers form axoaxonic synapses with trigeminal fibers entering the brain stem through the trigeminal root. The effect of electrical stimulation of the third nerve central stump on the central endings of trigeminal afferent fibers consists in an increased excitability, possibly resulting in a presynaptic inhibition. This inhibitory influence is due to both direct and indirect connections of the third nerve afferent fibers with the trigeminal ones.

Action Potentials↗
PubMed1987

Localization and somatotopy of sensory cells innervating the extraocular muscles of lamb, pig and cat. Histochemical and electrophysiological investigation.

The localization of sensory cells innervating the extraocular muscles (EOMs) was studied in the lamb, pig and cat in which horseradish peroxidase (HRP) was injected into each EOM. Electrophysiological techniques were also used to search for EOM stretch sensitive units in the semilunar ganglion. In lamb and pig labeling was observed in the semilunar ganglion only, while in cat labeled neurons were present in both the semilunar ganglion and mesencephalic trigeminal nucleus. In the semilunar ganglion of all these species a clear somatotopic organization of EOM afferents was observed. The histochemical somatotopic pattern of EOM afferents in the semilunar ganglion of lamb and pig was substantially in agreement with the electrophysiological arrangement. The responses recorded to EOM stretch in the semilunar ganglion of the pig were characterized by a low threshold and a slow adaptation as previously found in the lamb; on the contrary, in the semilunar ganglion of the cat only a few units were found, which showed high stretch threshold and quick adaptation.

Animals↗
PubMed1985

A scanning electron microscopic study of the mesencephalic trigeminal nucleus in duck and rabbit.

The mesencephalic trigeminal nucleus (MTN) cells of both young and adult ducks as well as of rabbits were investigated by scanning electron microscope. The rabbit showed only ovoid unipolar cells, while the duck also presented polyhedral cells. Few of these latter revealed processes originating from their surface and were recognized as multipolar cells. Some differences between the MTN cell surface of young and adult ducks were noticed. Synaptic bulbs were observed on the MTN cells in both duck and rabbit.

Animals↗
PubMed1983

Localization of neurons innervating masticatory muscle spindle and periodontal receptors in the mesencephalic trigeminal nucleus and their reflex actions.

The mesencephalic trigeminal nucleus was studied in anaesthetized and curarized rabbits by recording the unitary activity through extracellular microelectrodes and identifying the constituent cell types. Two types of units were found, namely primary afferents supplying jaw raising muscle spindles and periodontal or gingival mechanoreceptors. These two groups of neurons exhibited a rostrocaudal somatotopy: the former occupied the entire rostral portion of the nucleus (A7-P2.3; trochlear decussation being taken as an arbitrary 0 level), the latter was located caudally (P3-P4.5) while the somata of both types of afferent fibres were present between P2.2 and P3. No evidence was found for representation of both tendon organs of jaw muscles and joint receptors. Among the units innervating muscle spindles, secondary afferents were largely more numerous than the primary ones. Among periodontal and gingival mechanoreceptor afferents, incisors were the most widely represented, followed by interalveolar gingiva and molars; the axonal conduction velocity ranged between 9 and 40 m/sec and between 8 and 16 m/sec for ipsilaterally and contralaterally projecting neurons, respectively. The motor responses obtained by electrical stimulation of discrete areas of the MTN confirmed the presence of a high degree of segregation between the two different populations of neurons. In fact, jaw raising movements are obtained when stimulating the area within A7 and P2 containing the somata of spindle afferent neurons, while only jaw opening movements are elicited by stimulation of the caudal levels of the nucleus. These data also show that the periodontal neurons whose somata are located in the MTN participate in the jaw opening reflex, just as the more numerous periodontal mechanoreceptors whose somata are located in the Gasser ganglion. Soma-somatic and soma-axon hillock gap junctions were found among the neurons of the MTN, particularly in the caudal third of the nucleus.

Animals↗