Light and transmission electron microscopic study of spinal cord in embalmed and fresh cadavers.

Objective : To observe and differentiate histological structures and ultrastructures by light microscope and transmission electron microscope between embalmed cadaveric spinal cord and fresh cadaveric spinal cord. Methods : The spinal cords were dissected from seven embalmed cadavers of the Department of Anatomy, Faculty of Medicine Siriraj Hospital, Mahidol University. The specimens were prepared for routine hematoxylin and eosin (H&E) staining for light microscope (LM)study. Some of the specimens were prepared to study by transmission electron microscope (TEM). Finally we observe and compare between spinal cord from embalmed cadaver and fresh cadaver. Results : By viewing with light microscope, the quality of spinal cords from embalmed cadavers are better and clearer than from fresh cadavers. Viewed by transmission electron microscope, the lipid part in the spinal cord from cadaveric embalmed tissues is degenerated but the protein part is not deformed. Conclusion : The spinal cords from cadavers which were fixed by excess formalin injection and embalmed in formalin for 1-2 years , are well-preserved for hematoxylin and eosin (H&E) staining techniques for light microscope (LM) study in Histology. However in the EM of spinal cord sections from embalmed cadavers, the protein component was more likely withstand to formalin and embalmment procedures compared to the lipid componennt (e.g.myelin sheath, cell membrane).

The histology of the pineal gland in cadaveric embalmed specimens.

Objective: This study is to observe ultrastructurally of the pineal gland from cadaveric embalmed specimens by light microscopy (LM) and transmission electron microscopy (TEM) Methods: Ten pineal glands were removed from cadaveric embalmed specimens. Each pineal gland was disected into two groups, one was put into 10% formaldehyde and the other was put into 2.5% glutaraldehyde. The first group was processed for light microscopy. First of all, fixed the tissues in formalin and then embedded in paraffin. Next, serially sectioned at eight micron and finally stained. Staining methods were (i) haematoxylin and eosin, (ii) Masson-Fontana method for melanin. The second group well preserved in 2.5% glutaraldehyde was chosen to prepare for the TEM. Results: Only five out of ten cadaveric pineal glands viewed by light microscopy were well preserved. In LM, we saw clearly that all ultrastructures or morphology of the cadaveric embalmed pineal gland cells were the same as the standard textbook. Melanin pigments were accumulated in both of the cytoplasm of pinealocytes and the stroma of pineal gland proved by Masson-Fontana staining. Mast cells were found throughout the gland but preferably found in the connective tissue trabeculae. A neuronal-like cell was found in the parenchyma of pineal gland. Extrapineal and intrapineal calcified concretion called corpora arenacea or brain sand were presented. Intrapineal concretions in the parenchyma were globular and concentric lamellar patterns while extrapineal concretions which were adjacent to the capsule were concentric lamellar only. TEM of pineal gland showed that it was moderately preserved in the chemical fixative of this formula. Cadaveric pinealocyte showed some organelles and chromatin extraction while the environmental fibrillar structures were well preserved. Conclusion: The histological findings in the pineal glands from cadaveric embalmed specimens are similar to fresh cadavers. Moreover, they can be used to prepare the normal slides for Histology Lab of the second year medical students. The presences of the melanin pigments in the cytoplasm of pinealocytes and stroma, mast cells, corpora arenacea, and neuronal-like cells confirm the previous studies.

The occipito-hypothalamic interconnection fiber within the fornix: (The first report).

Objective: To demonstrate the occipital crus of the fornix from the brain of Thai cadavers and provide here the first finding and the first report. Methods: 10 brains of Thai cadavers, 5 males and 5 females, were bisected. Each half was further dissected to demonstrate the inferior horn, the body and the collateral trigone of the lateral ventricle by removing the cerebrum from the superior part down and backwards. The dissection also removed the body of the corpus collasum and left only the splenium portion. When exposing the inferior horn and the collateral trigone, the hippocampal formation was situated at the inferomedial aspect. We can see the fornix arises from the fimbria of the hippocampus and curves anteriorly to terminate at the mammilary body and the septal nuclei. Another 15 sets of horizontal brain sections and 15 sets of coronal brain sections also helped in confirming this report. The sections passed through the crus of the fornix were selected and observed. Results: We can define and demonstrate another crus of the fornix, which arises from the occipital lobe of the brain, the occipital crus. This crus may arrange in a round elevated bundle or a flat bundle beneath the ependyma and join the posterior part of the hippocampal crus of the fornix at the medial border of the body of the lateral ventricle. Conclusion: The fornix is the fiber which originates from the hippocampal formation to be the fimbria and leaves the hippocampus as the crus part of the fornix. Then it curves superiorly anteriorly and inferiorly to terminate at the septal nuclei and the mammillary body. Another crus of the fornix comes from the occipital cortex posteriorly and joins together with the hippocampal crus to terminate in the same area. This suggests that the occipital crus of the fornix involves in another part of the limbic structures that are responsible for the memory consolidation, emotions and autonomic responses.

The intersegmental anastomosis of the posterior spinal nerve rootlets of the Thais.

Objective: To demonstrate the percentages of the type as well as the frequencies of the rootlet anastomoses in all levels of the spinal cord of the Thais. Methods: Spinal cords and meninges were dissected from the vertebral columns of 42 Thai cadavers at the Department of Anatomy, Faculty of Medicine Siriraj Hospital. The dura and arachnoid maters were carefully dissected along the median plane longitudinally to expose the spinal cord posteriorly. The posterior nerve roots, rootlets and cauda equina were carefully exposed for a clear vision. Each of the spinal cords was examined throughout its length looking for posterior rootlet anastomoses. Results: The percentages of intersegmental anastomosis between posterior rootlets were 45, 3, 29 and 23% in the cervical, thoracic, lumbar and sacral segments, respectively. Three types of intersegmental anastomosis, 1a, 1b and 2 were recorded. Conclusion: Intersegmental anastomosis of the posterior nerve rootlets was observed in every segment of the spinal cord; the highest incidence was found in the cervical segment. The findings in this study suggest a variable range of dermatome distribution at a higher extent than previously thought.

Two new standard lines of the external base of skull.

Objective: To propose another two new standard lines for the external base of the skull which pass across almost all significant foramens, for easier observation and to remember the sites of the foramen. Methods: 50 Thai dry skulls 24 males and 26 females were observed from the external base of skull. All of them were photographed and the imaginary oblique lines were drawn by the Photoshop program. 2 lines were drawn, firstly the medial oblique line and secondly the lateral oblique line. Results: The medial and lateral oblique lines, 50 right and 50 left sides of Thai skulls were passed along the same canals and foramens. There was no significant difference between the 2 sexes. These could be proposed to be standard lines. Firstly, the medial oblique line extends from the tip of the mastoid process medialward to the alar of vomer. This imaginary line passes across the stylomastoid foramen, the lateral border of the jugular foramen, the carotid canal, the foramen lacerum, the pterygoid canal and the alar of vomer. Secondly, the lateral oblique line extends from the anterior margin of the base of mastoid process medialward to the medial pterygoid plate. This imaginary line passes across the external auditory meatus, the mandibular fossa, the spine of the sphenoid bone, the foramen spinosum and the foramen ovale. Conclusion: We proposed another 2 imaginary lines at the external base of the skull for better alternative landmarks in finding the nerves and blood vessels that pass through the foramens in and out of the skull. The previous imaginary planes, the anterior and posterior transverse lines do not pass across the carotid canal and foramen spinosum. Therefore, we can alternatively use the medial and lateral oblique lines as landmarks to find almost all the important structures such as the facial nerve, the common carotid artery etcetera.

Intradural communication of L3 and L4 ventral nerve rootlets of spinal nerves.

Normally, the nerve roots within the dural sec never communicate with one another. Even the fusion of the ventral and dorsal nerve roots to form the spinal nerve occurs outside the dural sac. In dissecting the spinal cords of 54 cadavers, we found one abnormal case in which the ventral nerve rootlet of the L3 spinal nerve gave a branch which joined with the L4 nerve rootlet within the dural sac. This communication consisted only of motor fibers. This pattern is different from patterns of distribution of normal spinal nerves, which are described by their segmentation and peripheral distribution patterns, both of which occur outside the dural sac and comprise of both motor and sensory fibers. Several causes for this abnormality have been proposed. Firstly, some neurons of the L4 anterior horn may have interposed with the L3 anterior horn cells. These neurons may have given axons and which joined with the L3 spinal nerve, then split back to join with the L4 spinal nerve, to ultimately supply the myotome of the L4 somite. Secondly, the fusion of myotomes of several somites to form one specific muscle may have developed sooner than its nerve and may have influenced the communication between the L3 and L4 nerve rootlets within the dural sac. An ultrastructural study of the communication segment by TEM clearly reveals a bundle of myelinated nerve fibers which are all peripheral nerves with their Schwann cells covered externally.

The inferior transverse scapular ligament in Thais.

Eighty-four shoulders of cadavers were dissected to determine the prevalence of the inferior transverse scapular (Spinoglenoid) ligament. Three types of the structures, forming an arch above the suprascapular nerve ad vessels at spinoglenoid notch, were classified in this study. Type I, the inferior transverse scapular fascia, was found in 45 cases (53.6 percent). Type II, the inferior transverse scapular membrane, was present in 30 cases (35.7 percent). This membrane was formed by bands of fascia distinct from the surrounding tissues. Type III, the inferior transverse scapular ligament, was present in 9 cases (10.7 percent). The ligament extended from the lateral border of the spine of the scapula to the margin of the glenoid cavity. Type I was the most common and type III was the least. Type I and type Ii were not true ligament. The study can serve as a reference to the inferior transverse scapular ligament in Thai and remind the neurologist or neurosurgeon that suprascapular nerve compression may result from lesions of the inferior transverse scapular ligament.