Intermediary Cells Research Articles

Pathway of assimilate transfer between mesophyll cells and minor veins in leaves of Cucumis melo L.

Photoassimilating mature leaves of Cucumis melo exported carbon at a rate of 1.7 mg C·dm(-2)·h(-1). Radiolabeling with (14)C showed that stachyose and raffinose are the main carbohydrates translocated. Autoradiograms indicated that sieve elements of the abaxial phloem of minor veins are the sole conduits for carbon export from mature leaves and carbon import into immature leaflets. Sieve elements of the abaxial phloem are associated with intermediary cells which are intimately connected with the surrounding mesophyll cells by numerous plasmodesmata. Photoassimilate, labeled with (14)C, was released into the leaf apoplast and could be trapped in a buffer solution circulating over the abraded adaxial epidermis. Carbon efflux was 1% of the carbon-export rate. A comparable distribution of (14)C among the sugars, amino acids and organic acids, recovered from the free space and from leaf extracts, was recorded. The composition of released (14)C-labeled carbohydrates in the free space resembled the pattern of photoassimilate, but differed clearly from the translocate. Release of organic compounds into the leaf apoplast was stimulated by chelating agents like Na-ATP, ethylenediaminetetraacetic acid and ethylene glycol-bis(β-aminoethyl ether)-N,N,N',N'-tetraacetic acid; a correlation between carbon efflux into the apoplast and carbon export from the leaf was not detected. It is suggested that the release of organic compounds into the leaf apoplast of Cucumis melo is the consequence of a general leakage from mesophyll and vascular parenchyma cells. A selective release of transport oligosaccharides was not observed. The experimental results presented here do not preclude a symplastic transfer of assimilates in mature leaves.

Ultrastructure, plasmodesmatal frequency, and solute concentration in green areas of variegated Coleus blumei Benth. leaves

The photosynthetic tissue of green portions of variegated Coleus blumei leaves consists primarily of palisade and spongy parenchyma cells as well as bundle-sheath cells. The moderate numbers of plasmodesmata connecting these cells may be sufficient to provide a symplastic pathway for assimilates moving toward the minor veins. The minor veins, however, are unusual in having two sets of phloem-loading cells which have little symplastic continuity with one another: one consisting of large, peripherally located intermediary cells, and a second set made up of smaller, usually more internal companion cells, both sets having their associated sieve-tube members. The intermediary cells are connected to vascular-parenchyma and bundle-sheath cells by unique branched plasmodesmata which are particularly abundant at the bundle-sheath interface. In addition, numerous plasmodesmata-pore connections occur between the intermediary cells and their associated sieve-tube members. Neither the intermediary cells nor their sieve-tube members plasmolyze when treated with 1.4 M mannitol, whereas mesophyll and vascular-parenchyma cells plasmolyze at 0.5 M and bundle-sheath cells at 0.6 M mannitol. By contrast, the companion cells and their associated sieve-tube members are symplastically isolated from the bundle-sheath cells and the sieve-tube-intermediary-cell complexes, and share few plasmodesmata with the vascular-parenchyma cells. Moreover, the companion cells plasmolyze at 1.1 M mannitol and their sieve tubes at 1.3 M. The intermediary-cell-sieve-tube complex thus appears to be structurally equipped to load assimilates entirely via the symplast, while the sieve-tube-companion-cell complex is probably loaded from the apoplast.

A quantitative electron microscopic study of the effect of glucocorticoids in vivo on the early postnatal differentiation of paraneuronal cells in the carotid body and the adrenal medulla of the rat.

The postnatal differentiation of carotid body chief cells and endocrine adrenal medullary cells was comparatively examined during ontogenesis and in rats which were treated with dexamethasone for 7 days after birth. Ultrastructure and innervation of carotid body chief cells are mature in neonates according to the functional requirements of chemoreception. By the end of the first postnatal week, only an increase in number of dense core vesicles can be noticed, the concentration of which then will reach the adult level. Under the effect of dexamethasone most of the heterochromatin is transformed into finely dispersed euchromatin within the nuclei of carotid body chief cells. In the cytoplasm, the Golgi apparatus becomes larger and the granular endoplasmic reticulum hypertrophic. The number of catecholamines storing dense core vesicles increases considerably. The innervation density remains constant. In contrast to the carotid body chief cells, the adrenal medullary cells have not reached their definitive maturity at the time of birth. Besides phenotypes of adrenaline-cells, noradrenaline-cells and small granules containing cells, pheochromoblasts and intermediary cells can be seen as well. Their cytoplasm is sparse, the concentration of dense core vesicles and the innervation density very low. After 8 days of postnatal ontogenesis, pheochromoblasts and intermediary cells are no longer present in the adrenal medulla. In adrenaline-cells and noradrenaline-cells, important processes of growth can be noticed, the cytoplasm has grown in extent, the number of dense core vesicles doubled and the innervation density of single cells triplicated. Only the few small granules containing cells remain small. Under the effect of dexamethasone also in the nuclei of chromaffin cells a transformation of heterochromatin into euchromatin occurs. The increase in number of dense core vesicles is relatively lower than in carotid body chief cells. The significant growth of innervation density during the first postnatal week was inhibited. Our observations suggest that dexamethasone stimulates the synthesis of catecholamines in adrenal medullary cells of newborn rats less pronouncedly than in carotid body chief cells. This could be attributed to the inhibited formation of synapses of growing chromaffin cells and to the in vivo active endocrine counter-regulation.

Loading and translocation of assimilate in the fine veins of sunflower leaves

AbstractThe time course of loading and transport of assimilate in sunflower leaves was examined by pulse labelling with14CO2, followed by freeze drying or freeze substitution, and dry autoradiography at both low and high resolution. The five classes of veins, V1‐V5 (V5 being smallest), show a division of function: V5 and V4 are engaged in loading and short distance transport; V3 to V1, in long distance translocation. The first high concentration of14C is found in two or three phloem parenchyma cells (intermediary cells) of V5 and V4 veins. The sieve elements of V5 and V4 veins do not show comparable concentrations of14C at any time. Recently assimilated14C is transported by the intermediary cells for distances of about 0.5 mm to the V3 veins. In V3 to V1 veins translocation is in the sieve tubes. Transport in V5 and V4 veins is in two directions, that in V3 to V1, in one direction towards the petiole. The high concentration of14C formed in the intermediary cells does not increase further as the assimilate moves to the sieve tubes of the V3 veins, and so is probably the origin of the gradient that drives translocation.

Vascular System of the Fertile Floret of Anthoxanthum odoratum L.

Three collateral bundles occurred in the rachilla of Anthoxanthum odoratum L. at the base of the fertile floret shortly after anthesis. The anterior bundle closer to the insertion of the fertile lemma (bundle 3) produced the trace to its midvein and supplied all of the xylem and some of the phloem for the two stamens and the pistil. One of the pair of bundles on the posterior side of the rachilla (bundle 2) furnished traces to the two right laterals of the fertile lemma, and the other (bundle 1) furnished the traces to the two left laterals. Either bundle 1 or 2 supplied the trace to the fertile palea. The tracheary elements were contiguous from rachilla bundle to each trace, but sieve elements were consistently contiguous only in the trace to the midvein of the lemma. All of the xylem of bundles 1 and 2 entered the lemma and palea traces, but the sieve elements and associated intermediary cells combined with those of bundle 3 to form an undulating plexus around the tracheary elements from bundle 3, and the unit rose toward the stamens and pistil. All of the tracheary elements at this level in the rachilla and upward into the pistil were the anomalous ones typical of the xylem discontinuity. From the unified vascular tissue arose, first, a trace to the anterior stamen and, higher, a trace to the posterior stamen. As the insertion of the pistil was reached, four traces left the rachilla: the large placental bundle of sieve elements and the xylem discontinuity, two posterolaterals of sieve elements, and an anterior bundle of sieve elements. The placental bundle supplied the young seed and ended in the bottom of the chalaza with intermediary cells, which blended with those of the chalaza and nucellus.

Microautoradiographic studies of phloem loading and transport in the leaf of Zea mays L.

Microautoradiographs showed that [(14)C]sucrose taken up in the xylem of small and intermediate (longitudinal) vascular bundles of Zea mays leaf strips was quickly accumulated by vascular parenchyma cells abutting the vessels. The first sieve tubes to exhibit (14)C-labeling during the [(14)C]sucrose experiments were thick-walled sieve tubes contiguous to the more heavily labeled vascular parenchyma cells. (These two cell types typically have numerous plasmodesmatal connections.) With increasing [(14)C]sucrose feeding periods, greater proportions of thick- and thin-walled sieve tubes became labeled, but few of the labeled thin-walled sieve tubes were associated with labeled companion cells. (Only the thin-walled sieve tubes are associated with companion cells.) When portions of leaf strips were exposed to (14)CO2 for 5 min, the vascular parenchyma cells-regardless of their location in relation to the vessels or sieve tubes-were the most consistently labeled cells of small and intermediate bundles, and label ((14)C-photosynthate) appeared in a greater proportion of thin-walled sieve tubes than thick-walled sieve tubes. After a 5-min chase with (12)CO2, the thin-walled sieve tubes were more heavily labeled than any other cell type of the leaf. After a 10-min chase with (12)CO2, the thin-walled sieve tubes were even more heavily labeled. The companion cells generally were less heavily labeled than their associated thin-walled sieve tubes. Although all of the thick-walled sieve tubes were labeled in portions of leaf strips fed (14)CO2 for 5 min and given a 10-min (12)CO2 chase, only five of 72 vascular bundles below the (14)CO2-exposed portions contained labeled thick-walled sieve tubes. Moreover, the few labeled thick-walledsieve tubes of the "transport region" always abutted (14)C-labeled vascular parenchyma cells. The results of this study indicate that (1) the vascular parenchyma cells are able to retrieve at least sucrose from the vessels and transfer it to the thick-walled sieve tubes, (2) the thick-walled sieve tubes are not involved in long-distance transport, and (3) the thin-walled sieve tubes are capable themselves of accumulating sucrose and photosynthates from the apoplast, without the companion cells serving as intermediary cells.

A THREE‐DIMENSIONAL RECONSTRUCTION OF THE VASCULAR SYSTEM TO THE LODICULES, ANDROECIUM, AND GYNOECIUM OF A FERTILE FLORET OF PANICUM DICHOTOMIFLORUM (GRAMINEAE)

A three‐dimensional reconstruction of a fertile floret stele of Panicum dichotomiflorum approaching anthesis was made by a new technique using superimposition of tracings of 80, 1‐μm thick serial sections, cleared tracing film, and mounting adhesive. From a collateral bundle, which also served as the median trace to the fertile lemma, most of the vascular tissue branched adaxially and horizontally to become the sole vascular supply to the two lodicules, three stamens, and pistil. The xylem branched at a low level to form a broad and long vessel plexus. The phloem branched at a higher level to overlay the vessel plexus on the right and left with an arc of horizontal sieve tubes in a phloem plexus. Those sieve tubes and vessels which rose after branching from the horizontal plexi assumed a more vertical course in the floret stele. Traces to the right and left lodicules arose from the lower abaxial portions of the flanks of the floret stele. Vessels ascended vertically from the xylem plexus and passed through the phloem plexi and joined with the sieve tubes there to exit at the same level and become the right and left lodicule traces. The vascular tissues to the three filament traces arose from different higher levels of the stele. The sieve tubes for the median filament trace arose vertically from the abaxial side between but above the lodicule traces. At higher levels the sieve tubes for the lateral filaments rose from the horizontal arcs of the flanks of the stele and departed it tangentially. The vessels destined to the filament traces arose in the center of the floret stele from adaxial portions of the horizontal plexus, ascended between the arcs of phloem, exited the stele simultaneously above the phloem of the traces, and followed the courses of their respective sieve tubes. The adaxially displaced apex of the floret stele then contained the vascular tissue related to the pistil. All the sieve tubes and vessels of the floret stele were embedded in a matrix of intermediary cells. The peripheral intermediary cells associated with the vessel plexus were xylem transfer cells with pronounced wall ingrowths. At higher levels in the floret stele, intermediary cells in scattered locations near sieve tubes or vessels had less conspicuous wall ingrowths. No preferred orientation of transfer cells with any particular trace was noted.

A Three-Dimensional Reconstruction of the Vascular System to the Lodicules, Androecium, and Gynoecium of a Fertile Floret of Panicum dichotomiflorum (Gramineae)

A three-dimensional reconstruction of a fertile floret stele of Panicum dichotomiflorum approaching anthesis was made by a new technique using superimposition of tracings of 80, 1-μm thick serial sections, cleared tracing film, and mounting adhesive. From a collateral bundle, which also served as the median trace to the fertile lemma, most of the vascular tissue branched adaxially and horizontally to become the sole vascular supply to the two lodicules, three stamens, and pistil. The xylem branched at a low level to form a broad and long vessel plexus. The phloem branched at a higher level to overlay the vessel plexus on the right and left with an arc of horizontal sieve tubes in a phloem plexus. Those sieve tubes and vessels which rose after branching from the horizontal plexi assumed a more vertical course in the floret stele. Traces to the right and left lodicules arose from the lower abaxial portions of the flanks of the floret stele. Vessels ascended vertically from the xylem plexus and passed through the phloem plexi and joined with the sieve tubes there to exit at the same level and become the right and left lodicule traces. The vascular tissues to the three filament traces arose from different higher levels of the stele. The sieve tubes for the median filament trace arose vertically from the abaxial side between but above the lodicule traces. At higher levels the sieve tubes for the lateral filaments rose from the horizontal arcs of the flanks of the stele and departed it tangentially. The vessels destined to the filament traces arose in the center of the floret stele from adaxial portions of the horizontal plexus, ascended between the arcs of phloem, exited the stele simultaneously above the phloem of the traces, and followed the courses of their respective sieve tubes. The adaxially displaced apex of the floret stele then contained the vascular tissue related to the pistil. All the sieve tubes and vessels of the floret stele were embedded in a matrix of intermediary cells. The peripheral intermediary cells associated with the vessel plexus were xylem transfer cells with pronounced wall ingrowths. At higher levels in the floret stele, intermediary cells in scattered locations near sieve tubes or vessels had less conspicuous wall ingrowths. No preferred orientation of transfer cells with any particular trace was noted.

VASCULAR SYSTEM OF LODICULES OF DACTYLIS GLOMERATA L.

The vascular system for the two lodicules in a floret of Dactylis glomerata L. was studied in serial sections. The floret stele contained a few modified tracheary elements and xylem transfer cells enveloped by a phloem of squat sieve-tube members and intermediary cells. A single sieve tube and associated phloem parenchyma exited the right and left sides of the stele and upon nearing the base of each lodicule branched and formed the minor veins of the lodicule. The minor veins underwent limited branching and anastomosing to form a small three-dimensional system which described an arc during its ascent in the adaxial portion of each lodicule. The sieve tubes in the minor veins extended halfway up the lodicule and contained short sieve-tube members with transverse, slightly oblique, or lateral simple sieve plates. The associated phloem parenchyma cells were intermediary cells, companion cells, and less intimate parenchyma cells. Intermediary cells terminated the minor veins and touched the distal ends of the terminal sieve-tube members, which lacked distal sieve plates. Although the transverse area of the sieve-tube members remained constant up the lodicule, the transverse area of the associated phloem parenchyma fluctuated.

Vascular System of Lodicules of Dactylis glomerata L.

The vascular system for the two lodicules in a floret of Dactylis glomerata L. was studied in serial sections. The floret stele contained a few modified tracheary elements and xylem transfer cells enveloped by a phloem of squat sieve-tube members and intermediary cells. A single sieve tube and associated phloem parenchyma exited the right and left sides of the stele and upon nearing the base of each lodicule branched and formed the minor veins of the lodicule. The minor veins underwent limited branching and anastomosing to form a small three-dimensional system which described an arc during its ascent in the adaxial portion of each lodicule. The sieve tubes in the minor veins extended halfway up the lodicule and contained short sieve-tube members with transverse, slightly oblique, or lateral simple sieve plates. The associated phloem parenchyma cells were intermediary cells, companion cells, and less intimate parenchyma cells. Intermediary cells terminated the minor veins and touched the distal ends of the terminal sieve-tube members, which lacked distal sieve plates. Although the transverse area of the sieve-tube members remained constant up the lodicule, the transverse area of the associated phloem parenchyma fluctuated.

Splenic B cells function as immunogenic antigen-presenting cells for the induction of effector T cells.

Previous studies performed in our laboratory have revealed that an ordered, sequential, tricellular interaction is obligatory for the antigen-driven induction of a specific effector memory T cell. Thus, it was found that antigen-pulsed peritoneal macrophages signal, in spleen cells, the generation of antigen-specific initiator lymphocytes. These lymphocytes, following injection to syngeneic recipients, recruit, in the draining lymph nodes, "virgin" antigen-reactive T lymphocytes. Although the nature of the first and last cell in the interacting sequence was well characterized, the identity of the intermediary initiator splenic cell was obscure. Studies were carried out to characterize the nature of the splenic initiator cells. It was found that spleen cells from nu/nu, adult thymectomized and neonatal thymectomized, or spleen cells from normal donors which had been subjected to cytolysis using anti-Thy-1.2 antibodies in the presence of complement, did generate, following interaction with keyhole limpet hemocyanin (KLH)-fed macrophages, specific initiator cells. Carrageenan impairment of spleen macrophages did not affect the generation of initiator cells, nor did the depletion of dendritic cells from the spleen. On the other hand highly enriched B cell, but not highly enriched T cell populations, when seeded on KLH-pulsed macrophages, generated antigen-specific initiators, which, in vivo, recruited antigen-reactive T cells. It thus appeared that B lymphocytes can function as intermediary obligatory antigen-presenting cells and actively transfer immunogenic signals from peritoneal antigen-presenting cells to T lymphocytes. These findings may therefore suggest that antigen-specific B cells do not function solely as antibody-producing cells, but, once activated by macrophages, may control the induction and differentiation of some antigen-reactive T cell subsets. Thus, one can view the B cell as an important regulatory cell of both cellular and humoral immune functions. The significance of this observation with regard to Ir gene control at the level of B lymphocytes is discussed.

Translocation in Saccorhiza dermatodea (Laminariales, Phaeophyceae): anatomy and physiology

An anatomical, ultrastructural, histoautoradiographic, and physiological study was made of the kelp Saccorhiza dermatodea, which possesses an anatomy "atypical" of Laminariales. A freeze-substitution – histoautoradiographic procedure localized 14C-labelled organic matter in highly elongated cells (solenocysts) in the medulla of Saccorhiza. These cells are the major long-distance, symplastic translocation pathway in this alga. Solenocysts are joined to each other via numerous lateral connections involving small intermediary cells called allelocysts. Sieve plates (pore diam: ca. 0.05 μm; pore density: ca. 100 μm−2), pierced by plasmodesmata in which an occasional tubule may be seen, are present at all allelocyst–solenocyst junctions as well as at intercellular connections in the cortex and meristodermal layers. Solenocyst ultrastructure closely resembles that of typical sieve cells of Laminariales. Secondary wall deposition occurs between June and October constricting the numerous lateral sieve plates and nearly occluding the cell lumen; however, no callose plugging was observed in any of the medullary cells. In vivo14C-photoassimilate transport was monitored in S. dermatodea blades using a Geiger–Müller probe. The translocation velocity was estimated at 60–100 mm∙h−1 with a greater translocation rate during the day than at night. Amino acid analyses of the S. dermatodea exudate showed a high alanine and glycine content with maximum concentrations 300 mm above the blade base. Nearly 90% of the 14C activity in both source and sink portions of the blade was in alcohol-soluble matter at the end of 72-h experiments. The unique anatomy of the Saccorhiza blade lends it to experimental exploration of the translocation process in kelp.

Vascular Anatomy of Angiospermous Leaves, with Special Consideration of the Maize Leaf

AbstractIn this brief review an attempt has been made to discuss some of the important features of the vascular anatomy of angiospermous leaves, especially those related to assimilate transport. Accordingly, emphasis has been placed on the small or minor veins, which are closely related spatially to the mesophyll, and which play a major role in the uptake and subsequent transport of photosynthates from the leaf. The small veins are enclosed by bundle sheaths that intervene between the mesophyll and vascular tissues and greatly increase the area for contact with mesophyll cells. In the minor veins of dicotyledonous leaves, parenchymatic cells having organelle‐rich protoplasts and numerous cytoplasmic connections with sieve elements dominate quantitatively. It is these so‐called intermediary cells that apparently are directly involved with the loading of assimilates into the sieve elements. In the maize leaf the small and intermediate bundles have two types of sieve tubes, relatively thin‐walled ones that have numerous cytoplasmic connections with companion cells, and thick‐walled ones that lack companion cells but have numerous connections with vascular parenchyma cells. The companion cell‐sieve tube complexes are virtually isolated symplastically from other cells of the vascular bundle and from the bundle sheath. Thick‐walled sieve tubes similar to those in the maize leaf have been recorded in the leaves of other grasses.

On the vascular anatomy and stomates of the lodicules of Zea mays

The four lodicules of the male spikelet of Zea mays L. are supplied by one, two, or three traces. In the lower regions of the traces intermediary cells and a few phloem transfer cells occur with the companion cells and sieve tubes. Xylem transfer cells with a variety of wall thickenings intermingle in the lower regions of the traces with tracheary elements. Tracheary elements and sieve tubes in this region do not touch but are separated by the phloem and xylem parenchyma. As the lodicule trace nears the base of the lodicule, intermediary cells and transfer cells diminish. A bundle sheath surrounds the lodicule trace but does not surround the minor veins of the lodicule proper. Within the lodicule proper the trace branches prolifically, and the minor veins become peripherally placed. Most of the minor veins contain vessels and sieve tubes but a few contain sieve tubes alone. Companion cells occur in some veins but not in others. Vessels and sieve tubes frequently touch each other. Many minor veins end simultaneously in sieve elements and tracheary elements but some end in one or the other cell type. Parenchyma cells with wrinkled walls occur near the minor veins. The abaxial epidermis of the upper regions of the lodicule contains stomates.

Ultrastructure of minor veins inCucurbita pepo leaves

The minor veins ofCucurbita pepo leaves were examined as part of a continuing study of leaf development and phloem transport in this species. The minor veins are bicollateral along their entire length. Mature sieve elements are enucleate and lack ribosomes. There is no tonoplast. The sieve elements, which are joined to each other by sieve plates, contain mitochondria, plastids and endoplasmic reticulum as well as fibrillar and tubular (190–195 Ā diameter) P-protein. Fibrillar P-protein is dispersed in mature abaxial sieve elements but remains aggregated as discrete bodies in mature adaxial sieve elements. In both abaxial and adaxial mature sieve elements tubular P-protein remains undispersed. Sieve pores in abaxial sieve elements are narrow, lined with callose and are filled with P-protein. In adaxial sieve elements they are wide, contain little callose and are unobstructed. The intermediary cells (companion cells) of the abaxial phloem are large and dwarf the diminutive sieve elements. Intermediary cells are densely filled with ribosomes and contain numerous small vacuoles and many mitochondria which lie close to the plasmalemma. An unusually large number of plasmodesmata traverse the common wall between intermediary cells and bundle sheath cells suggesting that the pathway for the transport of photosynthate from the mesophyll to the sieve elements is at least partially symplastic. Adaxial companion cells are of approximately the same diameter as the adaxial sieve elements. They are densely packed with ribosomes and have a large central vacuole. They are not conspicuously connected by plasmodesmata to the bundle sheath.

Multiple rough endoplasmic cisternae in the endocrine pancreas of the adult rat.

Multiple rough endoplasmic cisternae were found in the parenchymatous cells of the endocrine pancreas of the adult rat (alpha, beta, D and intermediary cells) and were especially developed in beta cells. They are considered to be normal constituents of the parenchymatous cells of the endocrine pancreas. Their close proximity to Golgi dictyosomes and the accumulation of secretory material sometimes seen at the extremities of such cisternae, suggest that they may have a role in the secretory activity of these endocrine cells.

DEVELOPMENT OF VAGINAL EPITHELIUM SHOWING IRREVERSIBLE PROLIFERATION AND CORNIFICATION IN NEONATALLY ESTROGENIZED MICE: AN ELECTRON MICROSCOPE STUDY.

Irreversible proliferation and cornification of the mouse vaginal epithelium were induced by 10 daily injections of 20μg estradiol-17β starting on the day of birth. Development of the irreversible vaginal epithelium during the period of estrogen injections in early postnatal life was observed under light and electron microscopes. Small electron-dense cells (A-cells) in clusters were present in the columnar vaginal epithelium of newborn mice. A-cells were proliferated by 2 daily estrogen injections. At the sites of A-cell clumps, large electron-dense cells (B-cells) characterized by long winding cytoplasmic processes appeared in mice given 3 daily injections, forming nodules which then fused together to form a layer under the columnar epithelium after 4 daily injections. In mice given 7 daily injections, the primary epithelium was shed by the superficial cornification of the newly formed layer. The B-cell membrane bore fewer desmosomes than in the basal and intermediary cells of the vaginal epithelium of ovariectomized 'normal' adult mice after 5 daily injections of 100μg estradiol-17β. Hyperplastic epithelial downgrowths in old ovariectomized mice given neonatal estrogen injections contained another type of cells with reduced density which formed much fewer processes and only a few desmosomes (C-cells).

Autonomic neurons in the spinal cord of the Rhesus monkey: a correlation of the findings of cytoarchitectonics and sympathectomy with fiber degeneration following dorsal rhizotomy.

AbstractCytoarchitectonic study of cell groups in the zona intermedia of the spinal cord led to the identification of the following nuclei in the rhesus monkey: n. intermediolateralis thoracolumbalis pars principalis et funicularis (ILp, ILf); n. intercalatus spinalis (IC); n. intercalatus pars paraependymalis (ICpe); n. intermediomedialis (IM); n. intermediolateralis sacralis pars principalis et funicularis (ILSp, ILSf); n. intercalatus disseminata (ICd); and n. torsade. Unilateral thoracic or abdominal sympathectomy, or both, performed in a second group of macaques, resulted in massive numbers of chromatolytic preganglionic neurons in IC, ILp and ILf. In the third group of macaques, dorsal rhizotomy followed sympathectomy. Fiber degeneration in these cases was stained with the Nauta and Fink‐Heimer methods. Despite variations in survivaltime and staining methods, no evidence was found for dorsal root terminal connections with the somata or proximal dendritic stems of chromatolytic sympathetic or parasympathetic visceral motor neurons (IC, ILp, ILf, ILSp, ILSf) although the same cases contained terminal fibers in n. marginalis of Waldeyer, substantia gelatinosa of Rolando, n. proprius cornus dorsalis (Pd), Clarke's column, n. intermediomedialis (IM) and among axial and appendicular somatic motor neurons. The present anatomical data suggest that, within the spinal cord, visceral reflex pathways are polysynaptic. Neurons in two or more spinal cell groups, IM, Pd and Cb (central basilar area of the dorsal horn) perhaps act as intermediary cells connecting dorsal root visceral afferent fibers with visceral motor (preganglionic) neurons. The visceral reflex pathway thus described includes a four neuron chain: dorsal root cell; IM, or Pd neuron, or both; preganglionic neuron; and the postganglionic neuron of the sympathetic system in the paravertebral or collateral ganglia, or the parasympathetic postganglionic neuron lying more distally.It was also found that many preganglionic neurons of the ILp, ILf and IC cell groups are as large as somatic motor neurons. Furthermore, the impression gained in this study is that visceral motor neurons appear in far greater numbers than somatic motor neurons.

Fibrinolytic activity of squamous epithelium of the oral cavity and oesophagus of rat, guinea pig and rabbit

The distribution of fibrinolytic activity in the tongue, cheek and oesophagus of rats, guinea-pigs and rabbits was studied in frozen sections by the histochemical fibrin slide-technique, a substrate film method. In all three species, fibrinolysis was caused by an activator of plasminogen. The activity was related to blood vessels, in the rats especially to arteries, and to the epithelial lining. In rats, the stratified squamous epithelium of the oral mucosa was fibrinolytically active while the epithelium of the oesophagus was inactive except for a discrete location at the oesophagogastric junction. In guinea pigs, the epithelium of the oral cavity and the entire oesophagus were weakly active, while in the rabbits both were inactive. The epithelial activity seemed related to the intermediary cells of the mucosa. Epithelial detachment or cellular injury appeared to enhance the fibrinolytic activity.

An Electronmicroscopic Investigation of the Young Gametophyte of the FernBlechnum Spicant(L.) Roth.

Abstract Four types of cells are present in the young gametophyte: basal, rhizoidal, apical prothallial and intermediary prothallial cells. A description of the fine structure of these four different cell types is given. The primary storage products in the spore cells are lipids and proteinaceous substances. These are used up during germination. The quantitative disposition of the organelles and storage products are described.