H3-thymidine was injected in a single dose into adult lizards Anolis carolinensis during early stages of tail regeneration when the new tail measured in length 2-5 mm (about 3 weeks). Electron microscopic autoradiography revealed that in the regenerating spinal cord three different cell types were recognizable four hours post-injection. By far the most common type was the ependymal cell. Ependymal or roundish cells with clear electron-density or storing bundles of intermediate filaments were occasionally found. A second rarer, cell type devoid of intermediate filaments was a pale round cell, often highly labelled. This cell showed a very poor ultrastructural differentiation and probably represents the precursor of the few neurons and glial cells observed in older stages of regeneration. The third type was a neuroblast at different degrees of differentiation and did not uptake H3-thymidine revealing it was a post-mitotic cell. Despite the relatively advanced ultrastructural differentiation of these neurons, synapses were rarely seen after three weeks of SC regeneration in Anolis.
By immunocytochemical methods, using colloidal gold particles coupled to antibodies, it is possible to label the occupied nuclear T3 receptors and observe them by electron microscopy. We carried out some experiments to validate these methods by testing the absence of non-specific binding of the antibodies to subcellular structures different from the T3 receptors. So, we have verified that the number of occupied T3 receptors in tissues from normal rats is lower in kidney cells than in heart and liver ones, a finding which is an agreement with data reported by others. The occupation of the receptors increases after T3 administration and decreases by triiodothyroacetic acid (Triac) administration to the rats, due to the displacement of T3 from the receptors with the latter. Our results are similar to those of the other authors using radioactive tracers. Non-specific binding was not detected. The occupied T3 receptors labelled with colloidal gold particles are located most commonly in the hetero/euchromatin interface. From our results we conclude that the colloidal gold particles observed by electron microscopy specifically label occupied T3 receptors, and the determination of the thyroid status at cellular level can be achieved using electron microscopy after labelling the receptors by immunocytochemistry with colloidal gold particles coupled to antibodies.
In the rabbit the myelinated fibres with the largest diameter originating from the sciatic nerve distribute mainly into the peroneal nerve, even though there is no difference in the density of myelinated fibres of the representative unit between the sciatic nerve and its branches. The distribution of the myelinated fibre diameters is unimodal in the sciatic nerve, but bimodal both in the peroneal and tibial nerves. The quotient axon diameter/fiber diameter (g ratio) shows a different trend between the sciatic nerve and the branches originating from it. Except for the peroneal nerve, the increase of the axon calibre corresponds to the reduction of the relative myelin sheath thickness and therefore to the reduction of internodal distance. The results show that the sciatic nerve and its terminal branches in the rabbit have morphometrical characteristics that are peculiar and differ from those of the other rodents.
The reproductive system of female quail embryo undergoes masculinization under the influence of chick and quail embryonic testis grafted into an extraembryonic coelom. Müllerian ducts undergo regression. The left gonad transforms into an ovotestis and the right gonad either does not develop or transforms into a small testis. Testicular chick or quail graft does not affect the development of the cortical ovarian-like region in the left testis of male hosts. In some quail testicular grafts developing in female quail hosts cortical region is retained longer than normally.
The parotid gland of the rabbit, a lagomorph species, was studied by ultrastructural techniques and carbohydrate ultracytochemical stainings. The rabbit parotid gland is a peculiar mixed gland consisting of serous and mucous secretory cells due to their histochemical properties supported by biochemical findings. Acinar cells exhibit heterogeneous features of secretory granules with different electrondensity and occasional presence of subunits. Intercalated duct cells show nuclei with deep indentation and apical granules partly similar to acinar secretory products. Striated ducts are characterized by three different cell populations, namely "light cells" with small secretory granules, "dark cells" rich of scattered mitochondria and typical striated cells. The presence of differentiated cell types within striated duct segments lends credence to the idea that, in addition to the role in electrolyte transport, some ductal cells may be involved in secretion and/or absorption of glycosylated products.
Vitamin D3, 25(OH) vitamin D3 and 1,25 (OH)2D3 were administered daily to unfed male Bufo andersoni for 15 days which resulted in a significant hypercalcemia and hyperphosphatemia in a dose-dependent fashion. 1,25(OH)2D3 is more potent than the other metabolites. The treatment activated ultimobranchial gland but induced degenerative changes in parathyroid of the toads.
The mode and the temporal sequence of the modifications undergone by permeability-related structures in the neural microvessels have been ultrastructurally and morphometrically investigated in optic tecta of 6, 14, and 18 incubation day (i.d.) chicken embryos and of 30 day chickens. Horseradish peroxidase was utilized as a permeability marker. The endo- and exocytosis-related structures (vesicles and vacuoles) and the interendothelial junctions remarkably change during development: the density of the vacuoles is decreased at the 14th i.d., while that of the vesicles becomes significantly low at the 18th i.d., both reaching lowest values in the chicken; the passage of the marker through the endothelial junctions begins to be hindered from the 14th i.d., parallel to the perivascular arrangement of astrocytic glia endfeet, and it is completely blocked at hatching time. The findings suggest that the optic tectum microvessels are permeable, and thus immature, in the early development and progressively acquire morphofunctional features of vessels provided with barrier devices during the pre- and post-natal development of the brain.
The vasopressin (AVP) positive elements of the hypothalamic supraoptic (SON) and paraventricular (PVN) nuclei, were investigated in 180 male rats through immunohistochemical, morphometric and statistical methods. The rats were subdivided in the next groups: 20 control rats; 40 rats treated with physiological saline intraperitoneal via (ip); 40 rats treated with physiological saline intracerebroventricular via (icv); 40 histamine (HA) treated rats, ip; and 40 HA treated rats, icv. The labeled nerve cells appear in the lateral part of the PNV and the SON of the control animals. These neurons have central nucleus and vasopressin positive cytoplasmic granulations. After the treatment with physiological saline, ip or icv, no alterations were observed. In HA treated rats, icv, numerous neurons strongly labeled were observed in these hypothalamic nuclei. Vasopressin positive nerve fibers and large droplets were also found both in the SON and in the PVN of these animals. The vasopressin positive material in the control rats and in HA treated rats, ip, is similar. The morphometric and statistical studies confirm these findings. The results are discussed in this paper.
The objective of this investigation was to analyse the organization of rubral afferents from the cerebellar interpositus nuclear complex (NI) in the rabbit. Free HRP was employed as a retrograde tracer to identify the distribution patterns of labeled cells in the anterior and posterior interpositus nuclei. The interpositus projections distribute throughout nearly the entire contralateral red nucleus (RN) except for its rostralmost parvocellular region (RN-PA) which does not correspond to the usually distinguished parvocellular subdivision of the red nucleus (RN-P). The central and lateral regions of the posterior interpositus nucleus (NIP) project (nearly exclusively) to the medial region of the RN. The lateral region of the anterior interpositus nucleus (NIA) sends projections to both the lateral and medial regions of the caudal three-quarters of the RN. Thus, the lateral region of the RN appears to be under nearly exclusive control of NIA. The rostral one quarter of the RN receives cerebellar afferents from the NIP only and caudal pole of RN from the NIA exclusively. Comparison of labelling patterns indicates absence of topogrophic differentiation of projections from the NIP, whereas dorsoventral topography in the NIA can correlate to the rostrocaudal and mediolateral arrangement of the RN. Collectively, interpositorubral projections in the rabbit are similar to those in other species only in basic features.
Amphibians are the most diverse group as regards the endocrinology of Ca homeostasis because in them only "true" parathyroid glands made first appearance but its involvement varies greatly according to their phyletic affinities and habitats. Presence of ultimobranchial gland, parathyroid and renal 25-hydroxyvitamin-D-1-hydroxylase enzyme in anurans represents their tetrapod pattern of Ca regulation. Among "higher" urodeles, both parathyroid and pituitary are involved in hypercalcemic regulation whereas in "lower" urodeles (some of them are "aparathyroid" too), pituitary alone appears to discharge this function. The latter situation is analogous to the fish. Apodans do possess ultimobranchial and parathyroid glands but the problem of their Ca metabolism has not yet been explored. This review deals exhaustively with the endocrinology of Ca metabolism in amphibians. Also, the evolution of hypercalcemic regulation in tetrapods will be discussed in the light of recent developments.
Among 23 5-day old mouse chimeras, 11 were sex chimeras. Four of them were hermaphrodites, six were males and one was female. In the gonads of three hermaphrodites fragments of ovarian tissue were very small. Growing oocytes were observed not only in ovotestes but also in testes. The course of transformation of ovotestes into testes is discussed.
The parotid gland of the hare Lepus europaeus was studied by electron microscopy. The parenchyma consists of secretory areas (acini) and ductal segments (intercalated, striated and excretory ducts). Acinar cells showed a marked heterogeneity due to the presence of secretory granules characterized by different size, electron-density and degree of membrane merging in addition to the occurrence of flattened and dilated rough endoplasmic reticulum. Acinar cells had variable affinity for PAS and PA-TCH-SP staining but were HID- and LIT-TCH-SP negative. Intercalated duct cells lacked secretory granules. Striated ducts were lined by four cell types namely light cells, dark cells, vacuolated cells, and typical striated cells. Excretory ducts showed some scalloping on the apical region of the light cells.
Forty-eight adult Wistar rats were divided into four groups for experimentation. The group I was used as a control and groups II, III and IV underwent progressive treadmill training. Samples of the red and mixed portions of m. gastrocnemius (lateral head) were stained with the histochemical technique of m-ATPase to determine the percentage of type I, IIA and IIB fibres, and with NADH-TR, in order to quantify variations in "low-oxidative" fibre percentages. The results showed that progressive training did not lead to statistical variations in the percentage of type I fibres. However, the proportion of type IIA fibres rose, while that of IIB fibres fell, in both cases significantly. Variations were more marked in mixed than in red Gastrocnemius muscle. A clear decrease was noted in "low-oxidative" fibres, which were virtually absent from red portion. This decrease was more marked, and occurred more rapidly, than in type IIB fibres.
Neuropeptide Y (NPY)-containing nerve structures were detected in the Syrian hamster gallbladder by using peroxidase-antiperoxidase immunohistochemical staining and immunoelectron microscopic techniques. In addition, Alcian blue-P.A.S. was used to differentiate two types of surface cells in the epithelium of the gallbladder: the columnar cells and the tuft cells. NPY-immunoreactive varicose nerve fibers were detected in the adventitial layer of the arterioles, precapillary arterioles and around axial venules of mucosal folds; they were not observed in the capillary beds. Since NPY is associated with norepinephrine (NE) in the sympathetic nerves, it could prolong the adrenergic vasoconstrictive effects. We propose that NPY and NE are simultaneously released to restrict the blood flow in the subepithelial capillary beds by increasing vascular resistance thereby perturbing the absorption of water and electrolytes.
In this article we have studied the topography, relationship and projection of the hippocampus in the dog by means of 1 mm thick transverse, horizontal and parasagital sections stained with Mulligan's reagent and 50 microns transverse sections (Nissl). The macroscopical disposition of this part of the CNS was completed by means of a gross dissection. Horizontal sections of 10 microns through the middle or limbic part were used to determine the general microscopic anatomy and to define the morphometry of its cells. From this point of view the Hippocampus of the dog appears to be intermediate between the rat and primates, species better studied.
Sixty-six Wistar rats of both sexes were divided into six groups. One group was used as control, and the others underwent different training schedules. Muscle samples taken from the red and mixed portions of m. Gastrocnemius (caput lateralis) were stained with m-ATPase in order to identify fibre types I, IIA and IIB. These fibres were measured in order to determine their minimum diameter. The most notable results obtained were: a) the three types of fibre were generally larger in males than in females; b) the mean minimum diameter of fibres from the mixed portion was smaller than those of the red portion, except type IIB fibres, and c) the training schedules involved generally led to slight hypertrophy of all types of fibres, although this finding was more significant in the mixed portion of m. Gastrocnemius.
Fetuses of pregnant CD-1 mice, exposed to intraperitoneal injection of 0.1% nicotine sulfate at a dose of 1.67 mg/kg body weight/day on gestational days 6-15, were compared with control (saline injected and non-injected) fetuses to assess the effects of nicotine on fetal growth in general and palatogenesis in particular. A total of 59 pregnant females (18 experimental and 41 control) were sacrificed on the 18 th gestational day and their fetuses were examined gross morphologically and histologically (using serial sections through the head in the frontal plane). Data analysis revealed that maternal weight gain, crown-rump length, fetal weight and head dimensions were significantly reduced in nicoted treated animals when compared to those of the controls. Histological examination revealed that 9.6% of fetuses of nicotine injected mothers presented clefts of the palate, whereas none of the control fetuses had that anomaly. It was concluded that nicotine has a detrimental effect on general growth and development as well as on palatogenesis of mice.
The ultrastructure and permeability to the marker horseradish peroxidase in the leptomeningeal and neural vessels of the optic lobes, and in the wing bud vessels, were compared, during early stages of chick embryo vasculogenesis, in order to ascertain whether young neural vessels, like mature ones, possess structural specificity preventing the free transport of molecules through their wall (blood-brain barrier). The results demonstrated that immature endothelia are always permeable to the tracer, since the marker passes the vessel wall through the interendothelial clefts (paracellular route) as well as by endo-exocytotic mechanisms (transcellular route). Nevertheless, the transport by vesicles is somewhat reduced in the neural vessels compared to that in the extraneural ones, suggesting that the former may be influenced by the surrounding neuropile to differentiate in a specific manner right from early development.
An immunohistochemical method, using glutaraldehyde fixation and a highly specific monoclonal antibody recently synthetized against dopamine (DA)-glutaraldehyde protein conjugate, permitted direct visualization of DA structures in the brainstem and spinal cord of a reptile (Chameleon). DA-immunoreactive cell bodies occurred in some contiguous areas of the midbrain tegmentum. The first one was located in the ventral tegmental area. Some somata intermingled with the oculomotor nucleus. The second group was the large round or oval DA-Immunostained neurons located in the substantia nigra. More caudally, a third group of round or fusiform DA-cell bodies was seen in an homologous area of so called mammalian A8 and were continuous with the substantia nigra group. In the medulla oblongata, the DA-containing cells were shown in the nucleus of solitary tract and in the dorsal lateral part of the dorsal motor nucleus of the vagus. The density of this DA-Immunoreactive neurons decreased more caudally. At the medullo-spinal level and upper cervical spinal cord, a few labelled cells were distinguished near the central canal. In the spinal cord DA-immunopositive cell bodies were observed in the vicinity of the central canal and formed a continuous column that extended throughout the rostral spinal cord. The apical processes of these neurons seemed to be in contact with the lumen of the central canal. This study constitute the first visualization of the immunoreactive DA-cell bodies at the medullo-spinal level which were already described, as TH immunoreactive in other species of reptiles.
