The study of the transverse sections of 7-10 somite chick embryos by the scanning electron microscopy and compared with the classical light microscopy.

Objective: To comparatively study the use of scanning electron microscopy and conventional light microscopy of the transverse sections of the 7-10 somite staged chick embryos as model for the study of development of human embryo. Methods: Conventional light microscopy and scanning electron microscopy had been applied as tools for the study of the chick embryos. Results: The results showed that scanning electron micrographs gave the clearer different views of chick embryo transverse sections as compared with the conventional light microscopy. Conclusion: From this study it was clearly shown that the three dimensional images obtained from scanning electron microscope could give comprehensive view of chick embryo specimens. Hence this should be the good alternative way for Embryology study.

Light and transmission electron microscopic studies of the third stage larvae of anisakis simplex.

Objective: The purpose of this study was to demonstrate the structures of the third stage larva of Anisakis simplex in marine fish by using light microscope (LM) and transmission and transmission electron microscope (TEM). Methods: L3 Anisakis simplex were processed for conventional light and electron microscopic studies. Results: The body wall of the L3 A. simplex is composed of three layers, the cuticle, hypodermis and somatic muscular layer from the superficial to deep surface of the worm, respectively. The cuticle is thick, functions as a protective barrier and barring the antigenic molecules. Furthermore, TEM reveals that the cuticle is subdivided into cortical, middle and basal layers from outer to inner part of the cuticle. This layer is highly filamentous and the filaments arrange randomly in several directions. The hypodermis is a thin layer which functions as the cuticular productive layer. The lateral hypodermal cords are bilobed. The somatic muscular layer is composed of a single row of muscle cells, which lie along the long axis of the body. The gastrointestinal tract of the worm is a straight tube, lined with stratified epithelium and surrounded by the basal lamina. The intestinal epithelial cells contain various organelles, which its luminal surface presents numerous microvilli for absorption of nutrient molecules. Conclusion: The cross section of LM and TEM can be used to distinguish the nematode species, as the LM reveals the lateral cords of L3 A. simplex are bilobed structures which are different from other species.

Light and electron microscopic studies of the structural damages of acanthamoeba cysts by pouzolzia indica methanolic extract fraction 4 solution.

Objective : This study was to investigate the morphological changes and ultrastructural damages of the Acanthamoeba cysts after treated with the minimal cysticydal concentration (MCC) of Pouzolzia indica methanolic extract fraction 4 solution by light and electron microscopies. Materials and Methods : Acanthamoeba cyst which prepared followed the method of Roongruangchai K15,16 were adjusted to the final concentration of 104 cysts/ml and treated with 1:4 soltion of fraction 4 Pouzolzia indica methanolic extract, the Thai medicinal plant. which was the minimal cysticidal concentration (MCC) 16. The cysts then, were centrifuged and the pellets were prepared for light, scanning and transmission electron microscopies. Result : Light micrographs showed the cytoplasmic clumping and some empty cyst wall. Transmission electron microscopy showed the ruptures of both ectocyst and the endocyst wall with some opercula damages. The cytoplasm aggregated and clumped. Scanning electron microscopy show steps of damage which started from shrinkage and collapsed of the cyst walls, then the cysts began to bulge and swell resulted in decreasing in the wrinkles of the cyst walls. The cytoplasmic contents drain out from the cyst wall and finally the cyst walls were ripped and torn into small pieces. Conclusion : Pouzolzia indica methanolic extract fraction 4 at the MCC of 1:4 caused structural damages to the Acanthamoeba cyst including shrinking of the cyst walls with the ruptured of the ectocyst, endocyst and operculum, edema and break out into pieces. The active ingredients of this Thai medicinal plant should be further studied as this can eventually be one of the regimen for the treatment of the Acanthamoeba keratitis or as a solution for cleaning the contact lens or contact lens case solution.

Phagocytosis: Mechanism of uptaking the nutrition of the embryonic cells.

Objective : To demonstrate the mechanisms of the embryonic cells, the epiblast, the mesoblast and the hypoblast of the chick embryo uptaking their nutrition by transmission electron microscopic (TEM) point of view. Materials and Methods : The chick embryos of about 18-27 hours incubation were used, the primitive streak and the 7 somites stages of the embryo were processed for routinely transmission electron microscopic study at the region of primitive streak, where the mesoblast originates from the epiblast. These stages correspond to the 15 days and 20 days of the human embryos, respectively. Results : The ultrastructural features of the epiblast, mesoblast and the hypoblast were observed. The epiblast cells arrange themselves as stratified columnar epithelium. The apical cells are columnar while the deeper cells are bottle-shaped and the deepest cells are round and separated to become the mesoblast. The superficial surfaces of the apical cells show many pseudopodia some of which curve to join with the adjacent. The clear materials are completely surrounded when the encompassing plasma membranes fuse and the membrane surround the engulfed material forms a vacuole, known as the phagosome, which detaches from the plasma membrane to float freely within the cytoplasm. The phagosome is then in some way recognized by one or more lysosomes which fuse with the phagosome to form the secondary lysosome. When the digestion is completed, the lysosomal membrane ruptures, discharging its contents into the cytoplasm. Undigested material remains within the membrane-bound vesicles called residual bodies, the contents of which later discharge at the cell surface by exocytosis. These processes also occur at the external surfaces of the hypoblast cells which arrange themselves as the simple squamous epithelium. The ventral plasma membrane shows many pseudopodia and also the series of phagocytotic process. The numerous clear vacuoles distribute in the cytoplasm of the epiblast and the hypoblast. These vacuoles are the nutritional uptake of the cell from the outside environment, the epiblast gets its nutrition from the albumin while the hypoblast from the egg yolk. Concluison: TEM evident shows clearly that numerous clear and unclear vacuoles distribute throughout the cytoplasm of the epiblast and hypoblast. These vacuoles are the phagosomes of several stages of phagocytosis, and serve as the nutritions for the cells, as the cells are still young and also have no definitive organelles to produce their own materials. This findings also give another excellent model of explaining the series of the phagocytotic process.

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.

Effects of streptozotocin-induced diabetes on lingual histological changes in the rats.

Background: Many studies suggest that taste disorders and tongue lesions associate with diabetes mellitus (DM). However, the lingual histopathology underlying impairments in taste sensation, swallowing and speaking in the DM is poorly examined. Objective: The present study aimed to clarify histological changes of the tongues in streptozotocin (STZ)-induced diabetic and control rats by using light microscopy. Materials and Methods: Eight male adult Sprague-Dawley rats; five STZ (60 mg/kg)-induced diabetic and three control rats, were studied. At 24 weeks after the induction, tongues were collected and processed by conventional histological technique with Masson’s trichrome staining. Results: In the DM, thickness of epithelium reduced, whereas that of keratin raised. Moreover, loss of characteristic layering was found. These cells became loss of chromatin. Furthermore, total numbers of taste buds in all types of lingual papillae per a tongue significantly decreased, when compared to those in the control. In both diabetic lamina propria and muscular layer, there were collagen fibers accumulations, numerous inflammatory cells, and swollen endothelial cells with narrowing of capillary lumen. In the muscular layer, average sizes of intrinsic skeletal muscle cells in all zones of diabetic tongue were significantly smaller than those in the control. Conclusion: It is possible that changes in histological characteristics of the tongue are important mechanisms underlying the development of taste disorders, impairments of swallowing and speaking in diabetic patients.

The origin of endoderm: Transmission electron microscopic point of view.

Objective: To show the transmission electron microscopic (TEM) evidence to confirm that the endoderm originates from the epiblast of the primitive streak or from other sources. Methods: 60 fertilized Leghorn hen’s eggs were used in this study by incubating the eggs for about 18-27 hours at 38oC, then the chick embryos of the primitive streak stage to 7-somite stage were further processed for routine TEM study at the region of the primitive streak. Results: The epiblast proliferates and accumulates to form the primitive streak at the midcaudal of the embryonic disc from 18-27 hours incubation which corresponds with the early third week of the human embryo. TEM evidence shows that the epiblast at the primitive streak is the stratified columnar type of epithelium while the hypoblast is the simple squamous and the mesoderm cells are irregular in shape. The process of gastrulation begins with the formation of the filopodia of the epiblast by numerous protrusions of the plasma membrane from lateral side of the cell. These structures initiate the separation of the contacted cells. The deepest epiblast cells separate first while the superficial epiblast cells exhibit the desmosome between the adjacent cells. The separated epiblast cells are bottle-shaped with numerous filopodia and gradually change the shape into round or oval cells which migrate in the space between the epiblast and hypoblast. Some of these migrate to the hypoblast and contact with the hypoblast, the mesoblasts lose the filopodia and gain more close contact to the hypoblasts which become a very thin sheet of cells. The facing cell membrane later gradually disappears and the mesoblast then occupies the region of pre-existing hypoblast. There is no evidence that the mesoblast displaces the pre-existing hypoblast laterally to form the extraembryonic endoderm. Conclusion: These are TEM evidences that the epiblast of the primitive streak separates and migrates to form the mesoblast and some contact with the hypoblast. The later process appeared to reveal that the mesoblast compresses the hypoblast until the facing plasma membrane disappears and occupies the region of the pre-existing hypoblast.

Several fractions of pouzolzia indica methanolic extract were lethal to the acanthamoeba cyst: in vitro study.

Objective: The purpose of this study was to compare the least concentrations of 5 fractions of Pouzolzia indica methanolic extract which can be lethal to the cyst form of the Acanthamoeba spp. Methods: Acanthamoeba spp. was isolated from a keratitis patient and was cultured using nonnutrient agar plates enriched with heat-killed E.coli for seven days at room temperature for the production of mature cysts. The cysts were harvested, washed in normal saline solution and adjusted to the final concentration of 104 cysts/ml. They were mixed with several dilutions of each fraction of Pouzolzia indica methanolic extract. After incubation for 1 hour, they were washed and centrifuged to remove the herbal extract supernatants. The cysts were recultured in the same medium for 7 days to confirm that they were all dead. Results: Pouzolzia indica methanolic extract fraction No. 1 which was eluted by water could not kill the cyst, while the crude extract (Fraction C) could at the concentration of 1:2. The fraction No.2 which was eluted by water: methanol had the minimal cysticidal concentration of 1:4, fraction No.3 which was eluted by methanol had the minimal cysticidal concentration of 1:8 and the fraction No.4 which was eluted by ethyl acetone had the minimal cysticidal concentration of 1:4. Concluison: Our results demonstrated that the Pouzolzia indica methanolic extract of several fractions can be cysticidal to an Acanthamoeba cyst, and this can modified to be a better disinfecting solution for contact lens cases.

Histological and ultrastructure of the peripheral nerve in cadaveric embalmed specimens and in fresh cadavers: the efficacy of several fixatives.

Objective: The study is to observe the histological structure and the ultrastructure of the peripheral nerve from cadaveric embalmed specimens and from fresh specimens by light microscope and by transmission electron microscope. Also to study the efficacy of the embalmed fixative to the tissue. Methods: The peripheral nerves were dissected from the arms of five cadavers of the Department of Anatomy, Faculty of Medicine Siriraj Hospital, Mahidol University, and from fresh cadavers. Each specimen was bissected, one put into 10% formaldehyde which was prepared for routine H&E staining and study by light microscope. The other was put into 2.5% glutaraldehyde, the best preserved specimen was then chosen to prepare for the TEM study. Results: There is no significant difference between the peripheral nerves of the cadaveric embalmed and the fresh specimens when viewed with the light microscope. On the otherhand when viewed by transmission electron microscope, the lipid part of the myelin sheath of the peripheral nerves from the cadaveric embalmed specimens are totally degenerated while the protein part is still intact. While in the fresh specimens which are fixed by 2.5% glutaraldyhyde, there is a complete preservation of the lipid and protein part of the myelin sheath. Conclusion: The cadavers were fixed by excess formalin injection into the femoral artery and embalmed in formalin for at least 1 year, this could not preserve the lipid part of the myelin sheath. However, in the fresh peripheral nerves fixed in 2.5% glutaraldehyde it could preserve the lipid and proetin parts of the myelin sheath perfectly.

Povidone – iodine induced changes in the cyst of Acanthamoeba spp.: transmission electron microscopic study.

Objective: This study was to investigate morphological changes and fine structures of the cyst form of Acanthamoeba after treatment with various concentrations of povidone – iodine (BetadineTM) using transmission electron microscopy. Methods: Acanthamoeba spp. were isolated from patients with amebic karatitis and obtained from the cultures on 3% non-nutrient agar (NNA) plates seeded with heat killed Escherichia coli (NNA-E coli) with incubation at 30°C for 7 days. The cysts were harvested and washed in ameba saline solution and adjusted to a final concentration of 104 cysts/ml. Various concentrations of povidone-iodine were put in the microtiter plate wells. The minimum cysticidal concentration was the lowest concentration that there was no excystment after 1 week of incubation. The cysts were prepared for routine transmission electron microscopy to determine the structural and organelle damages. Results: Structural damages were observed in the cysts treated with povidone-iodine of 0.04% dilution. Many cysts showed shrinkage of amoeba from the cyst wall and there was a slight withdrawal of the cytoplasm from the cyst wall. Many cysts were ruptured and broken into small pieces. Conclusion: Structural damages were observed in the cysts treated with 0.04% dilution of povidone-iodine solution or more than that. The damage started with pores produced in the cyst wall and the loss of water, shrinkage and loss of the cytoplasm of the inside cell from the cyst wall, followed by breaking of the cyst wall and the inside cell into small pieces.

Comparing lethal dose of povidone-iodine and virkon® to the acanthamoeba cyst: In vitro study.

Objective: To compare the least concentration of Povidone-iodine and Virkon®, phenolic-based compound with accelerated hydrogen peroxide and potassium peroxymonosulfate, which can cause a lethal effect to the cyst form of the Acanthamoeba spp. Methods: Acanthamoeba spp. was isolated from the keratitis patient and was cultured using amonoxenic medium supplement with heat killed Escherichia coli and incubated for up to seven days for the production of mature cysts. Acanthamoeba cysts on the culture plates were mixed with several dilutions of Povidone-iodine to compare to several dilutions of Virkon®. After incubation for 1 hour, they were washed and centrifuged to remove the chemical supernatant. The pellets of the mature cyst were viewed by a light microscope for seven days, and further recultured on the monoxenic medium to confirm that the cysts were all died (cysticidal) for seven days. Results: Povidone-iodine 0.04% and Virkon® 0.25% solutions were the least concentrations which could cause a lethal effect to the Acanthamoeba cyst. Conclusion: Our results demonstrated that both the Povidone-iodine and Virkon® showed antiamoebic activity. The further study should be done to determine whether Povidone-iodine and Virkon® can be used as a disinfecting solution for contact len cases.

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.

The ultrastructure of the parathyroid gland in cadaveric embalmed specimens.

Objective: This study is to observe ultrastructurally of the parathyroid gland from cadaveric embalmed specimens by light microscopy and by transmission electron microscopy. Methods: The parathyroid glands were carefully dissected from the posterior surface of thyroid glands of the cadavers of the Department of Anatomy, Faculty of Medicine Siriraj Hospital, Mahidol University. Each parathyroid was bisected into two, one put into 10% formaldehyde and the other to the 2.5% glutaraldehyde. The first group was prepared for routinely HE staining for light microscopy. The one which the specimen with the best preserved was chosen to prepare for the TEM. Results: The parathyroids of the cadavers were all well preserved as viewed by light microscopy. They are all reviewed the chief and oxyphil cells which easily distinguishable. The chief cells are more numerous and acquired the characters of actively synthesis of materials. These are the basophilic cytoplasm and large clear nucleus. The oxyphil cells are less numerous and acquired its characters of larger cells, red cytoplasm and dense dark nuclei. When viewed by TEM, it is cleared that the cells are well preserved. The chief cells are characterized by large heterochromatic nucleus and the cytoplasm is filled with the secretory vesicles, some of which the RER and the Golgi apparatus can be observed. Conclusion: The human tissue from the cadavers of the Department of Anatomy, Faculty of Medicine Siriraj Hospital was well preserved even viewed by TEM. This may be due to the fact that the fixative was pushed through the great vessels until it circulated throughout the blood vessels of the whole body. Especially the endocrine glands such as the parathyroids which were richen in blood supplies, the fixative might be forced through the capillary sinusoid and then this tissue is highly preservation.

Renal microvascular changes in streptozotocin-induced, long-termed diabetic rat.

OBJECTIVE: To investigate the renal microvascular changes in streptozotocin (STZ)-induced, long-termed diabetic rat. MATERIAL AND METHOD: Twelve male Sprague-Dawley rats were used. Each diabetic rat (n = 8) was induced by an intraperitoneal injection of STZ (60 mg/kg) in citrate buffer (pH 4.5). Control rats (n = 4) were injected intraperitoneally with the same amount of the buffer. The animals were sacrificed at 20 weeks after the injections. The kidneys were processed for conventional light microscopy (LM) and vascular corrosion cast technique with scanning electron microscopy (SEM). RESULTS: Under LM, it was found that the glomerular sizes intensively decreased in the long-termed diabetic rat. The thickening of Bowman's basement membrane was demonstrated. Additionally, there were macrophages and capsular drop lesions in renal corpuscles of long-termed diabetes. The sizes of proximal and distal tubules were markedly destroyed, when compared to the control. Moreover, the epithelial necrosis of vacuolated renal tubules was observed. By using vascular corrosion cast with SEM, the glomerular microvascular sizes in the long-termed diabetes were significantly decreased that corresponded to the result under LM. Furthermore, the size of peritubular capillaries decreased. Concerning to vasa recta in the long-termed diabetes, these vessels ran tortuously and decreased in size. CONCLUSION: Renal microvascular changes, observed in STZ-induced diabetic rats, mimic human diabetic nephropathy (DN). Additionally, the pathological changes of the renal tubules were investigated. Therefore, the present study provides an important basic knowledge for understanding the processes in developing DN, as well as for further study of the therapeutic treatment.

Pollen grains in stool examination may lead to misdiagnosis for the parasite ova: 3 case reports.

Three cancer patients were admited in Siriraj Hospital for chemotherapy. Routinely, the blood, the urine and stool examination have to be done for checking up / excluding other diseases. In the stool examinations of these patients, light microscopically revealed abundant oval-shaped organism-like structures. They looked like the ova stage of several parasites which could not give the diagnosis by the light microscopic level. Therefore the ultrastructural examination was performed by scanning and transmission microscopes. The TEM revealed clearly that they were not of animal structure because their walls were made up of plant tissue - cellulose. They were concluded to be the pollen grains of plants by comparing to the figure and description from textbooks of palynology, the study of pollen grains. They may be the pollen grains of the herbal medicine which were consumed by the cancer patients as an alternative treatment of the cancer. If light microscopic level cannot give the exact diagnosis, electron microscopy may be helpful.

The ultrastructure of the secretory cells of the human carotid body.

Objective: The purpose of this study was to study the ultrastructure of the human carotid body by using transmission electron microscopy. This is to distinguish the secretory cells of the human carotid body and classify the cells by the characteristic size, shape and electron density of the secretory granules, since nowadays there is still no data about TEM of the human carotid body. There is also no report about the exact secretions of the organ. Methods: 4 carotid bodies at the carotid bifurcations were identified and dissected from 2 fresh cadavers. The specimens were prepared for routinely TEM. Results: There are at least 3 secretory cell types in the human carotid body accordings to TEM. The cells were classified by the characteristic size, shape and the electron density of the secretory granules. The type I has large clear membrane bound granules, type II has small electron dense membrane bound granules and type III has large moderately electron dense membrane bound granules while type IV is thought to be the degranulated form of the type I. Conclusion: There are at least 3 types of secretory cell in the human carotid body and there may be 3 types of secretion as well. The immunocytochemical technique will be performed in future to identify the secretions.

Annular pancreas in Thais.

Objective: To study a congenital malformation of pancreas, the annular pancreas, and openings of pancreatic ducts. This abnormality can cause duodenal obstruction. Methods: The annular pancreas and duodenum of an 86-year-old Thai female cadaver was removed. The length and width of the annular pancreas were measured, as well as the internal diameter of the duodenum at the surrounded part and also the higher level. The openings of pancreatic duct were also carefully observed. Results: The second part of the duodenum was completely surrounded by the pancreatic tissue. The uncinate process extended over the anterior surface of the third part of the duodenum. The differences between the diameter of the duodenum at the surrounded part and at the higher level were 0.2 cm. there is no duodenal obstruction in this case. There were 2 openings of the pancreatic duct which opened to the second part of the duodenum. These ducts situated higher than the normal level, and were the primitive remains of the dorsal and ventral pancreatic buds. Conclusions: Not all the cases of the annular pancreas cause duodenal obstruction. In the cases that the pancreatic tissue loosely surrounds the duodenum, the diameters of the duodenum at the surrounding and at the slightly higher level are nearly the same. The pancreatic openings showed the primitive characters, i.e., there were 2 openings represented 2 origins of the pancreatic buds.