Anatomy and Embryology最新文献

Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) expressing cells were detected in pituitary, brain and ovary of the Perciform cichlid fish Cichlasoma dimerus. This detection was carried out by immunohistochemistry (IHC) and Western blot techniques using antisera of the Cyprinodontiform Fundulus heteroclitus raised against the conservative region of the teleost betaFSH and the betaLH subunits. The estimated molecular weights were 24 kDa for LH and 19 and 15 kDa for FSH. In the adult pituitary, both cell types were distributed along mid and ventral zones of the proximal pars distalis (PPD, mid-immunoreactive cells), and along the ventral and dorsal external border of the pars intermedia (PI, high-immunoreactive cells). Double IHC showed that FSH and LH are mainly expressed in different pituitary cells. FSH cells were detected in the pituitary around day 21 after hatching (ah) (prior to sex differentiation), while LH cells were detected by day 60 ah (during the sexual differentiation period). A correlation between gonadal sex differentiation and FSH was demonstrated in a 15 days organ culture system. FSH and LH neurons were localized in the nucleus lateralis tuberis and their fibers project through the ventral hypothalamus, preoptic area and neurohypophysis. FSH neurons differentiated on day 21 ah, while LH neurons appeared on day 15 ah. In the ovary, the immunoreactivity for both FSH and LH was restricted to the cytoplasm of previtellogenic and early vitellogenic oocytes.

The extrinsic and intrinsic respiratory nervous systems receive specific contributions from the vagal and sympathetic components. Using specific markers for vagal and sympathetic structures, we studied the distribution patterns of immunoreactivity to galanin (GAL), pituitary adenylate cyclase-activating polypeptide-27 (PACAP) and the tachykinin substance P in extrinsic and intrinsic nerve of chick embryo respiratory system, during development from the very early age to hatching. All peptides studied appeared in the intrinsic and extrinsic nervous systems early. We found substance P in both the vagal and sympathetic systems, PACAP in vagal components alone and GAL mainly in the sympathetic system. The intrinsic nervous system showed high immunoreactivity for all peptides studied. These data accord with the well known early trophic functions that peptides have on the development of nervous networks and modulatory activity on the intrinsic nervous system. The GAL again proves to be the main peptide in chick embryo sympathetic respiratory system.

The glycoprotein hormone stanniocalcin (STC) has originally been described in the teleost kidney. Since then, STC homologs have been identified in various genomes including human, mouse, rat, Xenopus and zebrafish. In mammals, two STC genes, STC1 and STC2, are known. We cloned a chicken STC homolog to analyze its expression pattern during chick development. Sequence analyses revealed a high sequence similarity of the chicken STC (cSTC) clone to mammalian STC2. Interestingly the expression pattern of cSTC2 largely resembles those of murine STC1: we found expression of cSTC2 in the nephric tubules, in the myocardium, in skeletal muscle cells from the onset of differentiation, and in synovial joint anlagen of the limbs.

A recently revealed important function of the amygdala (Am) is that it acts as the brain's "lighthouse", which constantly monitors the environment for stimuli which signal a threat to the organism. The data from patients with extensive lesions of the striate cortex indicate that "unseen" fearful and fear-conditioned faces elicit increased Am responses. Thus, also extrageniculostriate pathways are involved. A multisynaptic pathway from the retina to the Am via the superior colliculus (SC) and the pulvinar was recently suggested. We here present data based on retrograde neuronal labeling following injection of the fluorescent tracer Fluoro-Gold in the rat Am that the parabigeminal nucleus (Pbg) emits a substantial, bilateral projection to the Am. This small cholinergic nucleus (Ch8 group) in the midbrain tegmentum is a subcortical relay visual center that is reciprocally connected with the SC. We suggest the existence of a second extrageniculostriate multisynaptic connection to Am: retina-SC-Pbg-Am, that might be very effective since all tracts listed above are bilateral. In addition, we present hodological details on other brainstem afferent connections of the Am, some of which are only recently described, and some others that still remain equivocal. Following selective injections of Fluoro-Gold in the Am, retrogradely labeled neurons were observed in parasubthalamic nucleus, peripeduncular nucleus, periaqueductal gray, dopaminergic nuclear complex (substantia nigra pars lateralis and pars compacta, paranigral, parabrachial pigmented and interfascicular nuclei, rostral and caudal linear nuclei, retrorubral area), deep mesencephalic nucleus, serotoninergic structures (dorsal, median and pontine raphe nuclei), laterodorsal and pedunculopontine tegmental nuclei (Ch6 and Ch5 groups), parabrachial nuclear complex, locus coeruleus, nucleus incertus, ventrolateral pontine tegmentum (A5 group), dorsomedial medulla (nucleus of the solitary tract, A2 group), ventrolateral medulla (A1/C1 group), and pars caudalis of the spinal trigeminal nucleus. A bilateral labeling of the upper cervical spinal cord was also observed.

We investigated the histology and histochemistry (of carbohydrates and proteins) of the digestive tract of the freshwater stingray Himantura signifier. The alimentary tract consists of a mouth, pharynx, esophagus, stomach (with a descending cardiac and ascending pyloric part), anterior intestine (with an initial portion and a spiral intestine) and posterior intestine, ending in a cloaca. Histologically, three layers--mucosa, muscularis and adventitia/serosa--were defined from the mouth to esophagus and in the posterior intestine, whereas in the stomach and anterior intestine four layers were present, including a submucosa. The epithelial lining of mouth, pharynx and cloaca was of the stratified cuboidal type, whereas that of the esophagus and posterior intestine was stratified columnar. The stomach and anterior intestine were lined by a simple columnar epithelium with microvilli. Goblet cells were observed along the alimentary tract, except in the stomach. In the descending cardiac portion of this organ, gastric glands composed of oxyntic, oxyntic-peptic and peptic cells were observed. The anterior intestine presented a spiral valve with 11 folds, formed by mucosa and submucosa. The posterior intestine was particular in displaying a three-layered muscularis. Mucosubstances secreted along the alimentary tract contained both neutral and acid mucins, but in the stomach only neutral mucins were detected. The stomach presented intense protein content in the epithelial lining of the gastric pits. Enteroendocrine cells were identified in the stomach and intestine. Overall, our data offer a baseline for comparative purposes and future detailed ultrastructural and immunohistochemical studies.

An ultrastructural study was performed to investigate the type of cellular death that occurs in hippocampal CA1 field pyramidal neurons after 10 and 20 min of transient cerebral ischemia in the male adult Wistar rats, followed by 2, 4 and 10 days of reperfusion. The four-vessel occlusion method was used to induce ischemic insult for either 10 or 20 min, following which the animals were submitted to either 2, 4 or 10 days of reperfusion. The animals were then anaesthetised, and their brains removed, dehydrated, embedded, sectioned and examined under a transmission electron microscope. After ischemic insult, neurons from the CA1 field presented alterations, corresponding to the initial, intermediate and final stages of the degenerative process. The only difference observed between the 10 and 20 min ischemic groups was the degree of damage; the reaction was stronger in 20 min groups than in the 10 min groups. While neurons were found in the different stages of oncotic necrosis in all groups, differences were found between the groups in relation to prevalent stages. In both ischemic groups, after 2 days of reperfusion, the initial stage of oncotic necrosis was prevalent and large numbers of neurons appeared normal. In both groups, after 4 days of reperfusion, most of the neurons showed more advanced alterations, typical of an intermediate stage. In both groups, after 10 days of reperfusion, alterations corresponding to the intermediate and final stages of oncotic necrosis were also predominant. However, few intact neurons were identified and the neuropile appeared more organised, with numerous glial cells. In summary, the pyramidal neurons of the CA1 field displayed selective vulnerability and exhibited a morphological death pattern corresponding exclusively to an oncotic necrotic pathway.

In the last years several studies have shown that vascular endothelial growth factor (VEGF) is present in neural stem cells and mature neurons from different neural tissues where it may play an important role as a neuroproliferative and/or antiapoptotic factor. The olfactory neuroepithelium has the capability to replace dying neurons with new neurons formed by cell division from stem cells in the basal region of the epithelium. The present study demonstrates, for the first time, that VEGF is present in the olfactory epithelium, nerves and bulbs (both main and accessory) during the development of the toad Bufo arenarum. In this report, we detected VEGF immunoreactivity in mature olfactory neurons from early larval stages until the beginning of the metamorphic climax. VEGF expression decreases dramatically after metamorphosis. VEGF receptor Flk-1 was localized by immunohistochemistry, from premetamorphic larval stages until the climax in the neurons of the olfactory epithelium with a more intense labeling in the basal cell layer. Double-label immunofluorescence studies localized VEGF to the cytoplasm and the nucleus of mature neurons whereas Flk-1 was expressed in cell membranes. Flk-1 was present in neurons of both the main and accessory olfactory bulbs. After the end of metamorphosis, Flk-1 expression was limited to basal cells in the olfactory epithelium and Bowman's glands. The main and accessory olfactory bulbs showed the same pattern of Flk-1 immunostaining before and after the end of metamorphosis. The presence of VEGF and its receptor in the olfactory system suggests that VEGF may play an important role during neural development.

The mature rat parotid gland shows hardly any cell bodies of myoepithelial cells around the acini, only a few cell processes being visible. However, in the early postnatal period, the rat parotid gland shows many myoepithelial cell bodies around the acini, including the intercalated ducts. In order to clarify the reason for the disappearance of myoepithelial cells from the area around the acinus during postnatal development, changes in the number and distribution of myoepithelial cells in the rat parotid gland were examined histochemically and chronologically, with particular reference to cell proliferation and cell death. From day 7 to day 14, many myoepithelial cells showing a positive reaction with anti-actin antiserum were found around the acini and intercalated ducts, but thereafter the number of such cells decreased gradually, particularly around the acini, and had almost disappeared after day 35. BrdU/PCNA-positive myoepithelial cells surrounding the acini were easily detected on day 14, but disappeared by day 21, whereas BrdU/PCNA-positive acinar cells remained numerous even after day 21. TUNEL/ISEL staining showed no positive myoepithelial cells throughout the observation period. Transmission electron microscopy also demonstrated no myoepithelial cells with chromatin condensation characteristic of apoptosis through the observation period. These findings suggest that the main reason for the disappearance of myoepithelial cells from the area around the acinus during postnatal development is the large difference between the number of myoepithelial cells and that of acinar cells, because the acinar cells retain their proliferative activity even after myoepithelial cells have become quiescent.

The volumes of the nerve cell bodies and those of the enveloping satellite cell sheaths from spinal ganglia were determined by morphometric methods applied to electron micrographs in young, adult, old and very old rabbits. The mean volume of the nerve cell bodies increased progressively with age; this is probably related to the increase with age of the body size of the rabbits studied. The mean volume of the satellite cell sheaths did not differ significantly in young, adult and old animals, but was significantly smaller in very old animals. It is extremely unlikely that this marked reduction in the volume of the satellite cell sheath is the result of a pathological process. The mean value of the volume ratio between the satellite cell sheaths and the related nerve cell bodies did not differ significantly in young and adult animals, but was significantly smaller in old and very old animals. This ratio was particularly low in very old animals. Our analysis showed that in each age group the volume of the satellite cell sheath is linearly related to the volume of the related nerve cell body. This result suggests that in rabbit spinal ganglia the quantitative relations between glial and nervous tissue are tightly controlled throughout life. It is suggested that ganglionic neurons release signals to influence and control the volume of their associated glial tissue. Since satellite cells have important support roles for the neurons they surround, it is likely that the marked reduction in the volume of perineuronal sheaths in the extremely advanced age is accompanied by a reduction of those roles, with negative consequences for neuronal activity.

This study reports the morphology of the urethral sphincter in adult male rats, mainly the histological aspects, the features of the endplates, and the heavy myosin chain distribution in the striated fibres. First, the prostate is entirely out of the striated sphincter, which is surprising when compared to man. Second, the urethral striated sphincter consists of two lateral fascicles separated by an anterior and a posterior strip of connective tissue, which extend from the prostatic urethra (i.e. the part of the urethra which runs though the prostate) to the bulb of the penis. An additional third fascicle of striated muscle (SM) covers the caudal part of the anterior connective strip of the membranous urethra (i.e. the urethra which extends from its prostatic part to the bulb of the penis). In the membranous urethra, the striated sphincter surrounds directly the urethral lumen without intercalated smooth muscle. In urethral cross sections, the endplates detected by alpha-bungarotoxin, which binds to nicotinic receptors, are clustered in the postero-lateral part of the lateral fascicles. The cross-sectional area of the urethral striated fibres shows a bimodal distribution: the largest fibres are located at the periphery of the sphincter and these fibres express only fast myosin heavy chains (MHC) as shown by immunochemistry. The smallest fibres are less numerous and are situated near the lumen co-expressing fast and slow MHC. All the striated fibres express desmin and dystrophin as SM fibres do. Taken together, these results suggest that the urethral striated fibres in male rat present the same characteristics as those of the skeletal muscles. The predominance of fast fibres is consistent with phasic contractions playing a role not only during micturition and urinary continence but also probably during ejaculation.