The Pituitary Gland of the Roach Leuciscus rutilus

Three endocrine cell types were recognized in the proximal pars distalis (PPD) of the roach, Leuciscus rutilus, by electron microscopy. Two of these cell types are basophilic and assumed to be gonadotropic. The third cell type is acidophilic and its similarity to somatotropic (STH) cells is evident. Green fluorescent cells corresponding to cells with dense core vesicles of about 85 nm are scattered between the PPD and the proximal neurohypophysis (PNH). Their possible content of a catecholamine was demonstrated with microspectrofluorometric analyses. Four axon types with granules 65, 81, 110 and 137 nm in average diameter terminate at the basement membrane. Only fibers with granules of 81 nm enter the PPD to make synapses with the STH cells. Extensions of the basement membrane are continuous with the perivascular space and penetrate the endocrine tissue. It is postulated that axon terminals on the basement membrane are functionally equivalent to synaptic contacts on the endocrine cells. Axon type 4 has granules which in sizes correspond to those of cells in lateral and ventrolateral parts of the nucleus lateralis tuberis (NLT). A similar correlation is possible between axon type 3 and other cells in the NLT. This is in accordance with earlier conclusions of a regulation of the gonadotropic cells from the lateral (posterior) parts of the NLT.     

Pituitary cytology of the teleost fish Tilapia mossambica (Peters)

In the pituitary of Tilapia mossambica, eight cell types were identified on the basis of their staining reactions. the RPD consists of erythrosinophils and PbH positive cells. PbH cells border the NH and give amphipilic reaction to tri- and tetrachrome dyes and Halmi's stain. Erythrosinophils are also stained with acid fuchsin and orange G. The PPD is made up of acidophils and cyanophils. The acidophils are stained with orange G, acid fuchsin and erythrosin. These cells form a palisade zone between the neurohypophysis and the cyanophils. The cyanophils are AB, AF, ATh, PAS and aniline blue positive. They include both thyrotrophs and gonadotrophs and cannot be differentiated. The gonadotrophs may be those which are degranulated and vacuolated in the breeding season. The PI is formed of PAS- and PbH positive cells which lack any definite pattern of arrangement. Apart from the chromophils, scattered chromophobes were seen throughout the adenohypophysis. Occasionally, cells resembling the cyanophils of PPD were noticed in the RPD and PI also.     

The Pituitary Gland of the Roach Leuciscus rutilus

Three different endocrine cell types were identified by electron microscopy in the rostral pars distalis (RPD) of the roach, Leuciscus rutilus. The cells which are characterized by the morphology and sizes of their secretory granules are assumed to secrete prolactin, ACTH and TSH. Prolactin cells occur in two forms which could be separated on account of the sizes of their granules. Intra-peritoneal injections of reserpine had a strong and persistent effect 24 hours after the treatment. The prolactin cells with small granules reacted with a marked release of secretion. The border of the RPD is composed of a so-called double basement membrane in contact with the perivascular spaces and forms extensive ramifications into the rostral neurohypophysis (RNH). Nerve fibers of different categories terminate at the border and its network in the RNH. Substances released from these terminals may influence the endocrine cells of the RPD. The ACTH cells and the prolactin cells are innervated by axons with granules less than 100 nm. The nomenclature of type ‘A’ fibers and ‘B’ fibers is discussed because it was difficult to make a reliable discrimination of the fibers and their nature by the sizes of their granules. However, four types of nerve fibers were distinguished in connection with the RPD although the presence of more types was indicated. In all four types the size variations of the granules are great and overlapping. The average sizes of the granules in these fibers are 157, 114, 119 and 81 nm. The origin of the nerve fibers innervating the RPD is discussed. All morphological data indicate a complex hypothalamic control of the RPD of the roach.     

Electron Microscopy of Peripheral Nerves and Neuromuscular Junctions in the Wasp Leg

The peripheral nerve branch innervating the femoral muscles of the common yellow jacket (Vespula carolina) has been found to possess a thick lemnoblast basement membrane and a complex mesaxon. The term "tunicated nerve" is proposed to designate the type of peripheral nerve in which one or several axons are loosely mantled by meandering, cytoplasm-enclosing membranes of the lemnoblast. The peripheral axon courses longitudinally in a groove in the muscle fiber between the plasma membrane of the muscle fiber and a cap formed by lemnoblast and tracheoblast. The junction is characterized by apposition of plasma membranes of axon and muscle fiber, abundant mitochondria, and synaptic vesicles in the axon, and aggregates of "aposynaptic granules" plus mitochondria and endoplasmic reticulum on the muscle side of the synapse. Unlike the vertebrate striated muscle fiber, no complex infolding of the synapsing plasma membrane of the muscle fiber occurs. The "connecting tissue" of the insect is formed by tracheoblasts, their basement membranes, and the basement membranes of other cells. Further mechanical support is given by the ramifying tracheoles. The physiologic roles of the specialized structures are considered.     

Fine structure of pars neuro-intermedia of the loach,Misgurnus fossilis L.

Summary Two types of glandular cells are present in the pars intermedia of the loach, Misgurnus fossilis. Basophils are characterized by the presence in their cytoplasm of numerous secretory granules containing electron-dense and homogeneous material and by scarce endoplasmic reticulum. Weak acidophils contain in their cytoplasm abundant endoplasmic reticulum and numerous granules of different electron densities.The distal part of the neurohypophysis is composed of several types of neurosecretory axons, strongly branched pituicytes, numerous capillaries, and connective tissue elements. The axon terminals form the neuroglandular, neurovascular and neurointerstitial contacts. Some axon terminals are closely apposed to the basement membrane separating neurohypophysis from meta-adenohypophysis. At points of absence of continuity of this membrane, some neurosecretory axons become directly contiguous with cytoplasmic membranes of the intermedia cells.The investigation was partly supported by a research grant from the Zoological Committee of the Polish Academy of Sciences.     

鳗鲡繁殖生物学研究 Ⅱ.下海雌鳗脑垂体超显微构造的研究

神经垂体主要由神经分泌纤维、脑垂体细胞和微血管组成。神经分泌纤维主要是无髓鞘神经纤维,也有一些是有髓鞘神经纤维。神经垂体中还有一些多层体构造。神经分泌纤维有两个基本类型:A型纤维含有直径为1250—1750Å的神经分泌颗粒;B型纤维含有直径为450—1000Å的颗粒状囊泡。腺垂体的分泌细胞按其超显微构造的特点和所含的分泌颗粒大小不同可以区分为六个类型:催乳激素分泌细胞、促甲状腺激素分泌细胞,促肾上腺皮质激素分泌细胞、促生长激素分泌细胞、促性腺激素分泌细胞和后腺垂体的分泌细胞。       

Seasonal plasticity of the pituitary pars intermedia of the one-humped camel (Camelus dromedarius)

The pituitary pars intermedia of Camelus dromedarius is well developed and completely surrounds the pars nervosa. Two major groups of cells are present: endocrine (ec) and glial-like cells (glc). The ec group is composed of three morphologically distinct cell types. Type I, or polyhedral light cells (LC-I) and type II, or polyhedral dark cells (DC-II), have secretory granules of heterogeneous electron density whose size ranges from 170 to 300 nm. Type III cells are elongated with homogeneous electron-dense secretory granules of 80–200 nm. The glc make up an organized network, form follicles in the centrolobular zones and are positive for vimentin and S-100β immunolabelling. The nerve fibres penetrating the lobe are numerous, and can be classified into two types according to the membrane bound vesicles found in their endings (ne). Ultrastructural quantitative analysis revealed significant variations in PI elements between winter and summer seasons (F = 8.014, p = 0.006). DC-II cells characterized by developed biosynthetic machinery and a large pool of secretory granules storage are increased with the ne in winter. However, LC-I cells showing frequent cytoplasmic degranulation are predominant with glc in summer. Thus, important cellular remodelling occurs in the dromedary PI that may depend upon, or perhaps anticipate, external living conditions.     

The fine structure of a multiterminal innervation of an insect muscle

The detailed structure of nerve branches, neuromuscular junctions, and muscle fibers of a multiterminal innervation of cockroach abdominal muscle has been studied with the electron microscope. The muscle fiber is of the banded myofibril type; with paired mitochondria and abundant endoplasmic reticulum. The peripheral nerve branches are multiaxonal with large central axon and several small peripheral tunicated axons. Tracheoblasts closely accompany the nerve branches. The multiple neuromuscular junctions show typical axonal vesicles, muscle aposynaptic granules, and close plasma membrane apposition with no interposition of basement membrane material.     

The Fine Structure of a Multiterminal Innervation of an Insect Muscle

The detailed structure of nerve branches, neuromuscular junctions, and muscle fibers of a multiterminal innervation of cockroach abdominal muscle has been studied with the electron microscope. The muscle fiber is of the banded myofibril type; with paired mitochondria and abundant endoplasmic reticulum. The peripheral nerve branches are multiaxonal with large central axon and several small peripheral tunicated axons. Tracheoblasts closely accompany the nerve branches. The multiple neuromuscular junctions show typical axonal vesicles, muscle aposynaptic granules, and close plasma membrane apposition with no interposition of basement membrane material.     

Ultrastructure of retrocerebral complex of the earwig, Euborellia annulipes, and rôle of aorta as a neurohaemal organ

The ultrastructure of the retrocerebral endocrine-aortal complex of the earwig, Euborellia annulipes has been studied. The space between the inner and outer stromal layers of the aorta is occupied by numerous axon terminals and pre-terminals containing large electron dense granules (NS-I) of approximately 100 to 220 nm and a few axon terminals having small granules (NS-II) of approximately 40 to 90 nm; the former appear to belong to medial neurosecretory A-cells, and the latter to the B-cells of the brain. The corpora cardiaca consist of intrinsic cells with mitochondria and multivesicular bodies. Granules of type NS-II and NS-III are observed in the axon terminals and pre-terminals in the corpora cardiaca. The NS-II are identical to those found in the aorta and are probably the secretions of the lateral B-cells. Granules of type NS-III are 40 to 120 nm and electron dense, and are intrinsic in origin. Similar granules occur in the intrinsic cells of the corpora cardiaca. E M studies have confirmed the rôle of the aorta as a neurohaemal organ for the medial neurosecretory cells, and the corpora cardiaca for the lateral neurosecretory cells of the brain. The corpora cardiaca also act as a reservoir for the intrinsic secretion. The corpus allatum is a solid body consisting of parenchymal cells with prominent nuclei, mitochondria, and endoplasmic reticulum. In between its cells are occasional glial cells and also neurosecretory as well as non-neurosecretory axons. The gland is devoid of A-cell NSM.     

Functional cytology of the pituitary gland of the teleost Clarias batrachus (L.).

The RPD (rostral pars distalis) is formed of two cell types. The erythrosinophilic acidophils were hypertrophied in response to ammonium sulphate treatment and dark background adaptation. The response to former may be due to osmoregulatory involvement. The PbH positive corticotrophs were markedly hypertrophied and degranulated in response to metopirone and ammonium sulphate treatments. They were moderately activated in the dark and white background adapted fish. The PPD (proximal pars distalis) is composed of two types of cyanophils and acidophils. The thyrotrophs are identified by their hypertrophic response to radiothyroidectomy and thiourea treatment. They are distributed in the ventral part of the PPD, posterior neurohypophysis and PI (pars intermedia). The gonadotrophs which largely occupy the dorsal aspect of the PPD increase numerically as the gonads mature and become the major cell type before spawning. The acidophilic somatotrophs are distributed all over the PPD. They are the predominant cell type in the PPD of fish with immature gonads. They gave strong reaction to Baker's acid haematein indicating the presence of phospholipid. Both PbH and PAS cells of PI were stimulated in fish kept in dark background whereas they did not exhibit any obvious change under white background adaptation.     

Histophysiologic response of the pituitary-inertrenal system to salicylate and adrenocorticotropin in catfish, Heteropneustes iossilis (Bloch).

The interrenal and pituitary cells showed increase in nuclear diameter eight days after treatment with ACTH, salicylate or salicylate + ACTH. After ACTH treatment, however, the cytoplasm in the interrenal cells was granular. Similarly, the lead-haematoxylin positive (PbH + ve) cells in the rostral pars distalis also showed partial depletion of stainable granules after ACTH treatment. Salicylate or salicylate ACTH caused depletion of cytoplasmic material in both the interrenal as well as PbH + ve cells.     

Morphological examination of the termination pattern of substance P-immunoreactive nerve fibers in human antral mucosa

The termination pattern of substance P (SP)-containing axons in human antral mucosa was examined using immunohistochemical techniques at the light and electron microscopic level. SP-immunoreactive (IR) axons were found to extend towards the pit region of the glands, where intraepithelial axons were observed. Electron microscopy showed immunostained axon profiles in close contact with the basement membrane of surface mucous cells. Membrane-to-membrane contacts between labeled axons and myofibroblast-like cells were identified, and SP-IR axons that were apposed to the epithelium were also in contact with subjacent myofibroblast-like cells. The anatomical relationship between SP-IR axons and the cells of the muscularis mucosae was investigated by light microscopy. Immunoreactivity for alpha-smooth muscle actin (alpha-sma) was used to visualize the smooth muscle cells, and the alpha-sma-IR cells were found to create a network that surrounded the gastric glands. Immunostained varicose axons ran alongside and in close apposition to the labeled muscle strands. Ultrastructural examination showed close contacts between SP-IR axon profiles and smooth muscle-like cells. In conclusion, SP-containing neurons may be important for sensory and secretomotor functions in the human antral mucosa.     

Some observations on the fine structure of the sinus gland of a land crab,Gecarcinus lateralis

The dilated axon endings of the sinus glands of the brachyuran crab, Gecarcinus lateralis, are filled with homogeneously dense granules, each granule being bounded by a delicate membrane. The granules are of two orders of magnitude: 0.05 to 0.1 micro and 0.15 to 0.2 micro in diameter. Each axon ending contains granules of a nearly uniform size. Endings with granules of the larger size range predominate. Non-nervous cells endogenous to the sinus gland are scattered among the nerve endings. The cell contours are irregular, and cytoplasmic processes ramify between endings. The axons are unmyelinated, having only thin limiting membranes, and they possess many neurofibrils. Granules in preterminal portions of the axons tend to lie at the periphery of the fiber, and in some cases in chains at the core of the fiber. The granules appear to be storage and release centers for neurosecretory substances or their precursors.     

Morphological variation of immunoreactive cells positive to cholecystokinin 33 (10–20) and gastrin 34 (1–15) in human duodenum

Summary Human duodenal endocrine cells reactive with antibodies to cholecystokinin (CCK) 33 (10–20) and/or gastrin 34 (1–15) were studied by a combination of immunohistochemical and electron-microscopic methods. By immunohistochemistry, three types of endocrine cells were distinguished in human duodenal mucosa, i.e., those only positive for only CCK, those positive for both CCK and gastrin and those only positive for only gastrin. Ultrastructurally, the first cell type is characterized by many secretory granules with an eccentric dense core (mean diameter; 271+-74 nm). The second cell type, which was less frequent than the other two, has ultrastructural features that resemble type-I cells. The last cell type was composed of two types of cells containing small secretory granules identical to those of IG cells (mean diameter; 171+-31 nm) or large secretory granules indistinguishable from those of I cells (mean diameter; 286+-50 nm).     

Some Observations on the Fine Structure of the Sinus Gland of a Land Crab, Gecarcinus lateralis

The dilated axon endings of the sinus glands of the brachyuran crab, Gecarcinus lateralis, are filled with homogeneously dense granules, each granule being bounded by a delicate membrane. The granules are of two orders of magnitude: 0.05 to 0.1 µ and 0.15 to 0.2 µ in diameter. Each axon ending contains granules of a nearly uniform size. Endings with granules of the larger size range predominate. Non-nervous cells endogenous to the sinus gland are scattered among the nerve endings. The cell contours are irregular, and cytoplasmic processes ramify between endings. The axons are unmyelinated, having only thin limiting membranes, and they possess many neurofibrils. Granules in preterminal portions of the axons tend to lie at the periphery of the fiber, and in some cases in chains at the core of the fiber. The granules appear to be storage and release centers for neurosecretory substances or their precursors.     

Morphology of identified neurosecretory and non-neurosecretory cells in the cockroach pars intercerebralis

Electrophysiologically identified cells of the cockroach pars intercerebralis (Periplaneta americana) were injected with the dye Lucifer Yellow for morphological examination and with horseradish peroxidase for ultrastructural marking. In addition to this, uninjected cells were also studied to elaborate the findings from the injected material. The two electrophysiologically distinct classes of cells (type I and type II) correspond to two distinct morphological and ultrastructural classes. Type I cells are the medial neurosecretory cells of the pars intercerebralis, which project their axons to the retrocerebral neuro-hemal complex. Their cell bodies have a mean diameter of 17 microns, and they contain neurosecretory granules 200 nm in diameter. Arborizations emanate from the axon in the anterior part of the protocerebral neuropil. The type II cell bodies are larger (38 microns in diameter). Their axons project into the contralateral circumesophageal connective. These cells were usually multipolar, having somatic arborizations in the anterior portocerebral neuropil. The cell bodies contain vesicles 40 nm in diameter, numerous trophospongia, and a multi-layered glial envelope.     

Staining of proteoglycans in mouse lung alveoli. I. Ultrastructural localization of anionic sites

Summary In order to contrast anionic sites, in mouse lung alveoli, two staining procedures were applied: (a) staining with Ruthenium Red and Alcian Blue and (b) staining with Cuprolinic Blue in a critical electrolyte concentration method. The Ruthenium Red-Alcian Blue staining procedure revealed electron-dense granules in the alveolar basement membrane. The granules were closely associated with the epithelial cell membrane and continued to stain even when the procedure was carried out at a low pH, indicating the presence of sulphate groups in the granules.After staining with Cuprolinic Blue, electron-dense filaments, also closely associated with the cell membrane, became visible in the basement membrane of type I epithelial cells. Their length depended on the MgCl₂ concentration used during staining. At 0.4m MgCl₂, the length was mostly within the range 100–180 nm. Using a modified Cuprolinic Blue method, the appearance of the filaments closely resembled that of spread proteoglycan monomers with their side-chains condensed. The basement membrane of type II epithelial cells also contained filaments positive towards Cuprolinic Blue; their length, however, was smaller in comparison with those of type I epithelial cells. The filaments lay in one plane and provided the whole alveolus with an almost continuous sheet of anionic sites. Cuprolinic Blue staining also revealed filaments in the basement membrane of the capillary endothelial cells. Furthermore, Cuprolinic Blue-positive filaments (average length about 40 nm) became apparent in close contact with collagen fibrils and separated from each other according to the main banding period of the collagen fibrils (about 60 nm), indicating a specific ultrastructural interaction between these two components. Filaments connecting collagen fibrils with each other were also detected.     

Ultrastructure of midgut endocrine cells in the adult mosquito, Aedes aegypti

The ultrastructure of endocrine cells in the midgut of the adult mosquito, Aedes aegypti, resembled that of endocrine cells in the vertebrate gastro-intestinal tract. Midgut endocrine cells, positioned basally in the epithelium as single cells, were cone-shaped and smaller than the columnar digestive cells. The most distinctive characteristic of endocrine cells was numerous round secretory granules along the lateral and basal plasma membranes where contents of the granules were released by exocytosis. Secretory granules in each individual cell were exclusively of one type, either solid or 'haloed', and for all cells observed, the range in granule diameter was 60-120 nm. The cytoplasm varied in density from clear to dark. Lamellar bodies were prominent in the apical and lateral cellular regions and did not exhibit acid phosphatase activity. The basal plasma membrane was smooth adjacent to the basal lamina, whereas in digestive cells the membrane formed a labyrinth. Some endocrine cells reached the midgut lumen and were capped by microvilli; a system of vesicles and tubules extended from beneath the microvilli to the cell body. An estimated 500 endocrine cells were distributed in both the thoracic and abdominal regions of the adult midgut. In one midgut, we classified a sample of endocrine cells according to cytoplasmic density and granule type and size; endocrine cells with certain types of granules had specific distributions within the midgut.