A morphometric study of the carotid body in chronically hypoxic rats

We performed morphometric studies of carotid body in acutely and chronically hypoxic rats (inspired PO2 = 70 Torr, at sea level). Acute exposure was for the duration of about 10 min, and chronic exposure lasted for 28 days. We confirmed that the total volume of the organ increased by severalfold. At the light-microscopy level we found an enlargement of the volume density of the blood sinuses from 14 to 31% due to chronic hypoxia. The morphometric hematocrit increased from 39 to 70% paralleling changes in the conventionally measured venous hematocrit. These data do not show any specific plasma skimming in the carotid body blood vessels. With the electron microscope we found that the mean average volume of type I cells increased from 320 micron3 in controls to 1,120 micron3 in the chronically hypoxic rats without hyperplasia, whereas type II cells had increased in number without alteration in size. Qualitative observations revealed that the normal appearance of clusters of ovoid type I cells interspersed by capillaries had been transformed into a pattern of individual cells forming plates between expanded blood vessels with a large increase of contact area between the cells and vessels. Type II cells appeared to have proliferated without changes in individual size to cover the enlarged periphery of type I cells. The observed structural changes in the carotid body parenchyma and vasculature appear to be physiologically adaptive and provide further support for the idea that various elements in the organ are particularly sensitive to hypoxia.     

Adrenal lipid profiles of chemically sympathectomized normoxic and hypoxic neonatal rats.

Neonatal hypoxia is a common condition that elicits a coordinated endocrine response. In the neonatal rat, hypoxia induces an ACTH-independent increase in corticosterone which can be partially blocked by chemical sympathectomy. The present study sought to characterize the effects of sympathectomy on the adrenal lipid profile, since previous work suggested that augmented plasma corticosterone during hypoxia may be due to changes in adrenal lipid metabolism. Newborn rats were exposed to normoxia or hypoxia from birth to seven days of age, and guanethidine was used to produce the sympathectomy. Plasma epinephrine and norepinephrine were not significantly affected by hypoxia, while guanethidine decreased plasma norepinephrine in normoxic and hypoxic pups. Hypoxia alone increased the concentration of cholesterol esters in the adrenal gland; this increase was due to increases in cholesterol ester-associated oleic (18:1n9), docosahexaenoic (22:6n3), arachidonic (20:4n6), and adrenic (22:4n6) acids. Hypoxia also increased diglyceride-associated adrenic acid. Guanethidine treatment attenuated the hypoxia-induced increase in cholesterol ester-bound arachidonic and adrenic acids. Guanethidine also decreased saturated fatty acid concentrations and increased n3 fatty acid-enriched triglycerides. The results support the idea that the ACTH-independent corticosterone response to hypoxia in the neonatal rat is mediated by specific, sympathetically driven alterations in the adrenal lipid profile.     

The carotid bodies of spontaneously hypertensive rats (SHR): a functional and morphologic study

The parameters of the acid-base-state of the arterial blood were measured in spontaneously hypertensive rats of the Okamoto-strain (SHR) and in normotensive Wistar rats (NWR) of a random-bred strain. The animals were anaesthetized with chloralose-urethane and breathed normal air under sea-level conditions. Structure and size of their carotid bodies were studied by light-microscopic methods. When compared with the NWR, the SHR showed a respiratory alkalosis and enlarged carotid bodies. In the SHR, never in the NWR, the lumen of the branches of the glomic arteries was narrowed by pad-like structures. The data suggest that systemic hypertension leads to morphologically and functionally detectable alterations of both carotid body structure and function. The interdependence of arterial chemoreceptor activity, sodium household, and the adjustment of systemic arterial blood pressure is briefly discussed.     

Organ culture of human placental villi in hypoxic and hyperoxic conditions: a morphometric study

Previously published reports have claimed that human placental villi are capable of adapting to hypoxia by thinning of the placental barrier which normally separates the fetal from the maternal circulation. In order to examine this effect further, terminal villi from three normal mature placentas were cultured for periods of 1, 6 and 12 h at different oxygen tensions. Diffusion distance and capillary volume fraction were measured on 1 micron plastic sections on a blind basis, but no statistically significant differences were observed between the cultured sample groups and control material. It is concluded that placental villi show no adaptation to acute hypoxia when maintained in organ culture in vitro. It is possible, however, that they undergo changes in vivo, secondary to vasodilatation of the umbilical arteries and placental arterioles.     

Increase of melanogenesis by retinoic acid: an ultrastructural and morphometric study

Melanin is a dark pigment protecting the skin against UV radiation in some organisms. Studies on invasion and metastasis using retinoic acid as inhibitor agent are well known, but its role in melanin production (melanogenesis), especially at ultrastructural level and using morphometry were not well studied. In the present study, we analyzed the effects of retinoic acid on the melanosomes in B16F10 melanoma cells. These organelles were identified and quantified using routine electron microscopy and the specific HMB45 antibody. Other approaches such as immunofluorescence, and flow cytometry were also used. Our results indicated that retinoic acid increased the melanogenesis process in B16F10 melanoma cells. Furthermore, this work also provided evidence that this substance interferes at the subcellular level altering the numerical density of melanosomes, as well as the relative volume of the nucleus and nucleolus. In addition, the cells displayed altered morphology and an increase in the percentage of the relative volume of melanosomes, mainly the stages II-III and IV, leading to melanin formation. Furthermore, a decrease in the cells number after retinoic acid treatment was also observed.     

Ageing adipokinetic cells in Locusta migratoria: an ultrastructural morphometric study

Summary A morphometric study was made of the ultrastructure of adipokinetic cells in resting adults of Locusta migratoria at 3, 23, and 43 days after imaginal ecdysis. The nucleus, rough endoplasmic reticulum, and Golgi apparatus enlarge with age, which indicates that the synthesis and packaging of secretory substances increases during ageing. The size of the storage compartment, consisting of secretory and ergastoplasmic granules, does not increase earlier than 23–43 days after imaginal ecdysis. The lysosomal compartment markedly enlarges between 3 and 23 days; later on, the growth of this compartment, especially of autophagosomes, is less prominent. This suggests that lysosomal destruction initially compensates for the production of new secretory granules, assuming that exocytosis of secretory granules by adipokinetic cells is insignificant in resting locusts. Afterwards, lysosomal destruction may no longer be sufficient to prevent over-production of secretory granules, as is suggested by the increase in the number of these granules between 23 and 43 days. This coincides with the appearance of a considerable number of large ergastoplasmic granules, which represent a spatially more efficient form of storage of secretory material than the much smaller secretory granules. The increase with age in the amount of secretory products indicates that the biosynthetic activity of the adipokinetic cells is not (finely) tuned to their releasing activity.     

Effects of scrotal hyperthermia on Leydig cells in long-term: a histological,immunohistochemical and ultrastructural study in rats

We have previously demonstrated that scrotal hyperthermia induce Leydig cell (LC) damage in short-term. The objectives of this pilot study were to investigate morphological changes and regulation of steroidogenesis on LC in long-term and the time of observation were extended to investigate whether the LC would eventually make a recovery after scrotal hyperthermia. The rats were randomly allotted into one of four groups: A (control), B (70 days after scrotal hyperthermia), C (105 days after scrotal hyperthermia), D (140 days after scrotal hyperthermia); each group contain seven animals. Scrotal hyperthermia was carried out in a thermostatically controlled water bath at 43°C for 30 min once daily for six consecutive days. Control rats were treated in the same way, except the testes were immersed in a water bath maintained at 22°C. Hyperthermia applied rats were sacrificed under 50 mg/kg ketamine anaesthesia after 70, 105 and 140 days, and biopsy materials of testes were obtained for light and electron microscopic examinations. Morphologically normal and the number of testosterone positive LC was significantly higher in 140 days after last heat than all other heat treatment groups. In heat treated groups, a dilated smooth endoplasmic reticulum, swollen mitochondria, and vanished mitochondrial cristae were observed. In the 140 days after scrotal hyperthermia, the severities of degenerative changes of LC were less than that observed in the other heat treated groups. We conclude that, scrotal hyperthermia cause morphological damaging and impaired steroidogenesis in LC and recovery of these findings were noted first time in 140 days after the last heat treatment.     

Alveolar bone of BB/W rats: a morphometric and histochemical study

The present study reported histochemical changes in alveolar bone glycosaminoglycans (GAG) (using Safranin O) and in interdental bone height in three groups of BB/W rats: diabetic, diabetes prone, and diabetes resistant. Safranin O staining intensity suggested that total GAG levels were highest in diabetic bone (p less than 0.05 compared to diabetes resistant, p less than 0.005 compared to diabetes prone) but not significantly different between diabetes prone and resistant groups. Following chondroitinase AC and ABC digestion, staining reactions suggested that the highest levels of dermatan sulfate were in the diabetes resistant group (p less than 0.001 compared to diabetic, p less than 0.001 compared to diabetes prone) and the highest levels of chondroitin sulfates were in the diabetes prone group (p less than 0.001). Coincidently the mean height of diabetes prone interdental septum was significantly less than that of diabetes resistant or diabetic groups (p less than 0.05). The study suggested that 1) diabetes and "prediabetes" produce significant changes in levels of chondroitin 4, 6, and dermatan sulfates within alveolar bone, 2) in "prediabetic" animals, interdental bone loss occurs prior to the onset of clinical symptoms and in the absence of local irritating factors, the bone height appears to return to normal levels, and 3) there may be a correlation between alveolar bone height and relative levels of dermatan sulfate.     

A morphometric ultrastructural study of the nucleus of cerebellar granule cells

A quantitative approach to the nuclear ultrastructure of cerebellar granule cells is described here. The study was made using conventional electron microscopy from cerebellar cortices of adult rats by means of a semiautomatic image analyzer. The basic observation is that the nuclei of mature granule cells constitute a homogeneous population in terms of morphometric and stereologic data; in fact, the volume density of condensed chromatin within the nuclei remains practically constant in all nuclear sections. These results seem to indicate the existence of a cell-specific nuclear morphometric phenotype which might be considered as an effective criterion for the typification of this cellular lineage.     

Development of the chick chorioallantoic capillary plexus under normoxic and normobaric hypoxic and hyperoxic conditions: a morphometric study.

Fertile eggs from the domestic fowl were incubated under normobaric normoxic (21% O2), hypoxic (14% O2), and hyperoxic (40% O2) conditions in order to examine the influence of the prevailing oxygen level on the growth and maturation of the chorioallantoic membrane. Eggs were sampled at regular stages throughout incubation for morphometric analysis. Under normoxic conditions, maturation of the capillary plexus occurred in two distinct stages, both of which contributed to a reduction in the thickness of the air-blood barrier. Between days 6 and 10, the capillaries sprouted and fused to form a dense plexus. Subsequently, between days 10 and 14, this plexus invaginated into the chorionic epithelium. Differentiation of the chorioallantoic membrane appeared maximal by the end of this period. Hypoxia resulted in diminished growth of the embryo and chorioallantoic membrane, but in accelerated maturation of the capillary plexus. Hyperoxia had a less marked effect but appeared to retard the final invagination of the plexus, resulting in a thicker air-blood barrier.     

Folliculostellate cells in pituitary pars distalis of male viscacha: immunohistochemical,morphometric and ultrastructural study

Folliculostellate cells (FSC) have been reported in pituitary of several mammalian species. FSC morphology and secreted substances have been instrumental to the understanding of their function. The purpose of this work was to perform an immunohistochemical, morphometric and ultrastructural study of the pituitary pars distalis FSC in adult male viscacha and to analyze their relation with hormone secreting cells. Immunohistochemistry and image analysis were carried out in different sectors of the gland, from the middle (sector 1) to the glandular periphery (sector 5). Transmission electron microscopy with lanthanum as electrodense tracer was used. FSC formed follicles with PAS-positive colloid inside. They expressed S-100 protein mainly in both nucleus and cytoplasm. FSC were stellate-like in shape and exhibited short cytoplasmic processes that contacted with blood vessels and endocrine cells. In addition, some follicular colloids were immunostained with anti-S-100 protein. A few FSC were immunostained with anti-glial fibrillary acidic protein (GFAP) and anti-vimentin. The morphometric parameters analyzed (percentages of S-100-positive total, cellular and colloidal areas) increased from sector 1 to sector 3 and then decreased to sector 5. Hormone secreting cells, mainly lactotrophs, gonadotrophs and corticotrophs were associated with FSC and follicles. The ultrastructural study demonstrated that FSC developed junctional complexes and desmosomes between their lateral membranes. Lanthanum freely penetrated the spaces between granulated cells and FSC, but did not penetrate into the follicular lumen. In conclusion: 1) the differential expression of S-100 protein, GFAP and vimentin may indicate different physiological stages of FSC; 2) the expression of these proteins suggests a neuroectodermic origin of these cells; 3) FSC spatial distribution, association with endocrine cells, and the generation of an intercellular communication network suggest that FSC are involved in the pituitary pars distalis paracrine regulation of the viscacha.Key words: Lagostomus, pituitary, folliculostellate cells, immunohistochemistry, distribution, ultrastructure.     

An ultrastructural study of the carotid body of horse and dog

Summary Carotid body tissue from horse and dog has been investigated ultrastructurally. Several cell types are recognized: glomus cells which are regarded as chemoreceptors, sustentacular cells which enclose the glomus cells, and nerve fibers.The glomus cells contain electron dense granules which are interpreted as packages of biogenic monoamines. There are both dark and light glomus cells, the former containing more granules and ribosomes. Invaginations of the plasma membranes as well as free coated vesicles are often seen in the cytoplasm of glomus cells. Nerves within the glomus lobules are generally wrapped by sustentacular cells, but nerve endings are also seen in close contact with the glomus cells. Some endings contain synaptic vesicles as well as a great concentration of mitochondria. The corresponding fibers are thought to be efferent. Another type of contact is interpreted as en passant synapses of afferent fibers.The author wishes to express his gratitude to Professor L. Nicander who initiated this project and took most of the micrographs and to Professor Nils Obel and associate Professor Gustav Björk at the Royal Veterinary College for their valuable help with the surgical procedure and to Dr. Martin Ritzén of the Royal Medical College for making the tests for biogenic monoamines.     

Development of germ cell transplants: morphometric and ultrastructural studies.

Mouse-to-mouse transplants were studied at 10 min, 9 h, 24 h, 1 week, 1 month, 2 months, and 3 months post-transplantation. Data from a previous light microscope study were confirmed and extended using morphometric and ultrastructural techniques. As soon as 10 min after introduction of the germ cells from one mouse into the tubule lumen of a recipient mouse they developed relationships with small Sertoli cell processes. The extent of this surface-to-surface relationship increased in animals sacrificed up to 1 week post-transplantation. Most transplanted germ cells retained the characteristics of the donor germ cells after they had been isolated and pelleted. Nearly all transplanted cells eventually underwent phagocytosis by the recipient Sertoli cells. The presence of small apparent clones of germ cells after 1 week of transplantation indicated that some germ cells may divide and survive for short periods within the epithelium. No discernible qualitative subcellular changes in the host Sertoli cell accompanying the development of transplant spermatogenesis were noted. Macrophages were present in the region of the boundary tissue between myoid cells and appeared to increase in number in the peritubular tissue of transplanted testes. Images suggest that they migrated into the tubule to gain entrance to the lumen and there take on the form of activated macrophages. Some macrophages phagocytose sperm at 2 months and 3 months post-transplantation. A testis weight increase previously demonstrate to occur at 24 h post-introduction of germ cells was found to be due to an increase in the volume of the tubular lumen. The increase of lumen size at 24 h was not related to the volume of the injected material. It is suggested that the presence of injected cells, likely germ cells, in the tubule lumen stimulated increased secretion by the Sertoli cell.