Medulla of kidney – A Postmortem Grossmorphological Study in Bangladeshi People

Background: In Bangladesh, prevalence of kidney diseases is increasing day by day and it was observed that renal medulla is affected less in earlier period of life but in late period it becomes affected more. Moreover renal mass changes with age which affecting the medullary mass and consequently the number of medullary pyramids. So the present study was carried out to evaluate anatomical features of medulla and to count the medullary pyramids with age related changes in the number of the pyramids in Bangladeshi people. Study type: Cross sectional analytical type of study. Place and period of study: Department of Anatomy, Mymensingh Medical College, Mymensingh, Bangladesh from January 2004 to June 2005. Materials and methods: A total of 70 fresh human kidneys of both sexes and sides were collected from the morgue of Mymensingh Medical College at postmortem. The selected cases were between 5 to 60 years of age. The samples were divided into 3 different age groups (A: 05-15 years, B: 16-35 years, C: 36- 60 years) to observe the variations in number of medullary pyramid of kidney in different age groups. Results: Among three groups, highly significant (<0.001) differences were found statistically in the number of medullary pyramid. Conclusion: There were changes in the number of medullary pyramid of kidney in different age groups. DOI: http://dx.doi.org/10.3329/bjms.v13i2.18299 Bangladesh Journal of Medical Science Vol.13(2) 2014 p.155-157

Transcranial stimulation measures explored by epidural spinal cord recordings

In response to a single-electrical stimulus to the motor cortex an electrode placed in the medullary pyramid or on the dorsolateral surface of the cervical spinal cord records a series of high-frequency waves. This has been shown by various studies conducted on animals. Recording from the surface of the spinal cord during spinal cord surgery has provided evidence for the action of transcranial magnetic stimulation (TMS) and transcranial electrical stimulation (TES) on the human motor cortex. However, the interpretation of this data has been limited. This article explains both types of transcranial stimulation (magnetic or electrical) the direct recording of which shows that transcranial stimulation can evoke several different kinds of descending activities. The output also depends upon the representation of the motor cortex being stimulated.

Formation of Descending Pathways Mediating Cortical Command to Forelimb Motoneurons in Neonatally Hemidecorticated Rats

Neonatally hemidecorticated rats show fairly normal reaching and grasping behaviors of the forelimb contralateral to the lesion at the adult stage. Previous experiments using an anterograde tracer showed that the corticospinal fibers originating from the sensorimotor cortex of the intact side projected aberrant collaterals to the spinal gray matter on the ipsilateral side. The present study used electrophysiological methods to investigate whether the aberrant projections of the corticospinal tract mediated the pyramidal excitation to the ipsilateral forelimb motoneurons and, if so, which pathways mediate the effect in the hemidecorticated rats. Electrical stimulation to the intact medullary pyramid elicited bilateral negative field potentials in the dorsal horn of the spinal cord. In intracellular recordings of forelimb motoneurons, oligosynaptic pyramidal excitation was detected on both sides of the spinal cord in the hemidecorticated rats, whereas pyramidal excitation of motoneurons on the side ipsilateral to the stimulation was much smaller in normal rats. By lesioning the dorsal funiculus at the upper cervical level, we clarified that the excitation was transmitted to the ipsilateral motoneurons by at least two pathways: one via the corticospinal tract and spinal interneurons and the other via the cortico-reticulo-spinal pathways. These results suggested that in the neonatally hemidecorticated rats, the forelimb movements on the side contralateral to the lesion were modulated by motor commands through the indirect ipsilateral descending pathways from the sensorimotor cortex of the intact side either via the spinal interneurons or reticulospinal neurons.