Spermatogenesis and the Structure of the Mature Sperm in Nucella Lapillus (L)

1968 ◽  
Vol 3 (1) ◽  
pp. 95-104
Author(s):  
MURIEL WALKER ◽  
H. C. MACGREGOR
Keyword(s):  
Golgi Complex ◽  
Mature Sperm ◽  
Mitochondrial Membranes ◽  
Fast Green ◽  
Anterior Portion ◽  
Front End ◽  
Early Spermatid ◽  
Before And After ◽  
Spermatid Nucleus ◽  
Pass Through

The testis of Nucella consists of numerous tubules, all directed inwards and joining to form a common testicular duct. In a single tubule the spermatogonia lie round the periphery. Mature sperm line the lumen of the tubule. Cells in the same stage of spermatogenesis are grouped together and all members of a group pass through spermatogenesis in phase. Staining with fast green before and after treatment with Van Slyke reagent indicates a change from lysine-rich to arginine-rich histone in the maturing spermatid. Sperm of Nucella are motile throughout their length. The sperm are thread-like and about 80 µ long. The head is Feulgen-positive and about 40 µ long. The mid-piece lies behind the head and is about 8 µ long. The flagellum runs from the front end of the head to the tip of the tail; in the head it is completely surrounded by the nucleus. The spermatogonia contain two centrioles situated near the nucleus and a conspicuous Golgi complex. There are synaptinemal complexes in spermatocyte nuclei in the synapsis stage. In the early spermatid the centriole pushes a tube through the nucleus. This tube is lined by nuclear membrane and is occupied by the anterior portion of the flagellar shaft. The nucleus elongates and the nucleoprotein condenses into strands arranged helically along the long axis of the nucleus. These strands fuse to form lamellae, which disappear in the mature sperm. Mitochondria aggregate at the base of the early spermatid nucleus and form a loose spiral around the flagellar shaft. The outer mitochondrial membranes fuse. The mid-piece of the mature sperm consists of a large tubular mitochondrion enclosing a portion of the flagellar shaft. At the early spermatid stage a pro-acrosomal granule is formed from a large Golgi complex. From this the acrosome develops; it consists of a cone and an acrosome granule. There are two sets of microtubules associated with the acrosome, one lying within the cone, the other outside the cone and separated from it by a ‘ragged membrane’. The microtubules of the outer set extend backwards along the head for two-thirds of its length. The centriole which gives rise to the flagellar shaft lies at the anterior end of the head and is separated from the acrosome by a thin layer of nucleoprotein and a double layer of nuclear envelope. There is no second centriole or derivative thereof in the mature sperm. In the tail groups of coiled fibres are associated with each pair of the peripheral flagellar fibrils.

Botzinger complex region role in phrenic-to-phrenic inhibitory reflex of cat

1989 ◽  
Vol 67 (4) ◽  
pp. 1364-1370 ◽  
Author(s):  
D. F. Speck
Keyword(s):  
Nerve Stimulation ◽  
Phrenic Nerve ◽  
Inhibitory Response ◽  
Phrenic Nerve Stimulation ◽  
Bötzinger Complex ◽  
Before And After ◽  
Pass Through ◽  
Bilateral Lesions ◽  
Decerebrate Cats ◽  
Inhibitory Reflex

Neuronal recordings, microstimulation, and electrolytic and chemical lesions were used to examine the involvement of the Botzinger Complex (BotC) in the bilateral phrenic-to-phrenic inhibitory reflex. Experiments were conducted in decerebrate cats that were paralyzed, ventilated, thoracotomized, and vagotomized. Microelectrode recordings within the BotC region revealed that some neurons were activated by phrenic nerve stimulation (15 of 69 expiratory units, 9 of 67 inspiratory units, and 19 nonrespiratory-modulated units) at average latencies similar to the onset latency of the phrenic-to-phrenic inhibition. In addition, microstimulation within the BotC caused a short latency transient inhibition of phrenic motor activity. In 17 cats phrenic neurogram responses to threshold and supramaximal (15 mA) stimulation of phrenic nerve afferents were recorded before and after electrolytic BotC lesions. In 15 animals the inhibitory reflex was attenuated by bilateral lesions. Because lesion of either BotC neurons or axons of passage could account for this attenuation, in eight experiments the phrenic-to-phrenic inhibitory responses were recorded before and after bilateral injections of 5 microM kainic acid (30–150 nl) into the BotC. After chemical lesions, the inhibitory response to phrenic nerve stimulation remained; however, neuronal activity typical of the BotC could not be located. These results suggest that axons important in producing the phrenic-to-phrenic reflex pass through the region of the BotC, but that BotC neurons themselves are not necessary for this reflex.

Coiling of the Flagellar Shaft in the Head Region of the Mature Sperm of Nucella (Purpura) Lapillus (L.)

1969 ◽  
Vol 5 (1) ◽  
pp. 211-225
Author(s):  
MURIEL WALKER
Keyword(s):  
Sea Water ◽  
Nuclear Material ◽  
Sperm Nucleus ◽  
Mature Sperm ◽  
Langmuir Trough ◽  
Head Region ◽  
Anterior Portion ◽  
Normal Concentration ◽  
Ph Range ◽  
Dry Out

The sperm of Nucella are long and threadlike. The flagellar shaft runs from the acrosome at the front of the head to the tip of the tail. Its anterior portion, the head shaft, is ensheathed by the nucleus. If a suspension of sperm in normal-concentration sea water is observed under phase contrast, and allowed to dry out slowly, the nuclear material of sperm near the edge of the coverglass swells and the head shafts of these sperm are thrown into gentle spirals within the nuclei. In some sperm the nuclear material disperses completely, and the front threequarters of the head shaft springs into a tight right-handed coil of 5-7 turns. Instantaneous coiling of the head shaft may also be induced by treatment of the sperm with x 2 concentrated sea water or 0.01 % (w/v) solution of sodium lauryl sulphate in sea water. The enzymes pronase and trypsin at a concentration of 50µg/ml in sea water at pH 8.0 cause dispersion of the head nucleoprotein and subsequently the head shaft forms a loose coil. The appearance and activity of the sperm do not change perceptibly over a pH range of 5.5-8.5. Sperm spread on a Langmuir trough containing normal concentration sea water were negatively stained with phosphotungstic acid and examined with an electron microscope. After such treatment the nuclei are partially spread and the fibrils of the head shafts appear twisted as the wires of an electrical flex. The twisted flagellar fibrils are seen more clearly in negatively stained head shafts of sperm whose nuclei have been completely dispersed by spreading on a Langmuir trough containing x2 concentrated sea water. Negatively stained preparations of sperm treated with enzymes show sperm with twisted and coiled head shafts. The nucleoprotein of these sperm is disaggregated into strips or sheets, or may appear as a mass of branching fibres. The flagellar fibres of the enzyme-treated sperm are often bent or broken. Longitudinal sections of mature sperm heads show that in the intact sperm the fibres of the head shaft are not twisted but run straight throughout the length of the head. Sections from the testis and testicular duct show that microtubules are present in sperm in the testis but absent from mature sperm in the testicular duct. It is suggested that the head shaft, as a consequence of some event in spermiogenesis, has an inherent tendency to twist and coil but in the mature sperm it is ‘strait-jacketed’ by the sperm nucleus.

scholarly journals Emergency department front-end split-flow experience: ‘physician in intake’

2019 ◽  
Vol 8 (4) ◽  
pp. e000817 ◽  
Author(s):  
Sean S Michael ◽  
Daniel Bickley ◽  
Kelly Bookman ◽  
Richard Zane ◽  
Jennifer L Wiler
Keyword(s):  
Emergency Department ◽  
Cross Section ◽  
Medication Administration ◽  
National Sample ◽  
Intake Process ◽  
Front End ◽  
Unscheduled Care ◽  
Before And After ◽  
Single Centre Study ◽  
Discharged Patients

BackgroundEmergency department (ED) crowding is a critical problem in the delivery of acute unscheduled care. Many causes are external to the ED, but antiquated operational traditions like triage also contribute. A physician intake model has been shown to be beneficial in a single-centre study, but whether this solution is generalisable is not clear. We aimed to characterise the current state of front-end intake models in a national sample of EDs and quantify their effects on throughput measures.MethodsWe performed a descriptive mixed-method analysis of ED process changes implemented by a cross section of self-selecting institutions who reported 2 years of demographic/operational data and structured process descriptions of any ‘new front-end processes to replace traditional nurse-based triage’.ResultsAmong 25 participating institutions, 19 (76%) provided data. While geographically diverse, most were urban, academic adult level 1 trauma centres. Thirteen (68%) reported implementing a new intake process. All were run by attending emergency physicians, and six (46%) also included advanced practice providers. Daily operating hours ranged from 8 to 16 (median 12, IQR 10.25–15.85), and the majority performed labs, imaging and medication administration and directly discharged patients. Considering each site’s before-and-after data as matched pairs, physician-driven intake was associated with mean decreases in arrival-to-provider time of 25 min (95% CI 13 to 37), ED length of stay 36 min (95% CI 12 to 59), and left before being seen rate 1.2% (95% CI 0.6% to 1.8%).ConclusionsIn this cross section of primarily academic EDs, implementing a physician-driven front-end intake process was feasible and associated with improvement in operational metrics.

scholarly journals Eliminate the Queuing Time in the New Suez Canal: Predicting Adjustment on Ships’ Arrival Time under Optimal Non-Queuing Toll Scheme

2021 ◽  
Vol 9 (1) ◽  
pp. 70
Author(s):  
Pey-Yuan Sun ◽  
Chen-Hsiu Laih
Keyword(s):  
Arrival Time ◽  
Suez Canal ◽  
Management Decision ◽  
Large Size ◽  
Ship Owner ◽  
Entry Time ◽  
Before And After ◽  
Pass Through ◽  
New Suez Canal ◽  
Scheduled Time

In 2016, the construction of the New Suez Canal was completed, enabling most large-size vessels to pass through and causing more ships to queue into the canal. As the queueing problem at the entrance of the canal was anticipated to be serious, an optimal non-queueing toll scheme was previously established to eliminate the queueing phenomenon at the anchorage of the canal. However, no information about each ship’s arrival time adjustment under the optimal non-queueing toll scheme is available from the previous literature. To solve this problem, we derive a series of mathematical formulae for each ship’s arrival time, length of queuing time and entry time before, and after, implementing the optimal non-queueing toll scheme. The arrival time adjustments, which enable ships to enter the canal without queueing, could then be obtained. These results enable the Suez Canal authorities to draw up the ship’s arrival timetable under the optimal non-queueing toll scheme, so that the captain could follow to enter the canal. The above information that we provide would be conducive to the management decision for the canal authorities to implement such a toll scheme. Once a tolled ship could enter the canal at the scheduled time without queueing, the ship owner could accurately control the sailing schedule, and the use of the ship could be more efficient.

scholarly journals Intracellular coupling of bikunin and the heavy chain of rat pre-α-inhibitor in COS-1 cells

1997 ◽  
Vol 328 (1) ◽  
pp. 185-191 ◽  
Author(s):  
M. Anna BLOM ◽  
Maria THUVESON ◽  
Erik FRIES
Keyword(s):  
Aspartic Acid ◽  
Serum Protein ◽  
Heavy Chain ◽  
Golgi Complex ◽  
Intracellular Transport ◽  
Chondroitin Sulphate ◽  
Ester Bond ◽  
Aspartic Acid Residue ◽  
Pass Through ◽  
Chondroitin Sulphate Chain

Pre-α-inhibitor is a serum protein consisting of two polypeptides: bikunin of 16 kDa, which carries an 8 kDa chondroitin sulphate chain, and heavy chain 3 (H3) of 74 kDa. The two polypeptides are linked through an ester bond between an internal N-acetylgalactosamine residue of the chondroitin sulphate chain and the C-terminal aspartic acid residue of H3. Both bikunin and H3 are synthesized by hepatocytes and become linked as they pass through the Golgi complex. H3 is synthesized with both N- and C-terminal extensions which are released during intracellular transport. To be able to analyse the assembly of pre-α-inhibitor in detail, we have cloned and sequenced the cDNA of rat H3. Upon expression of the protein in COS-1 cells, both propeptides were found to be released. Furthermore, co-expression of H3 and bikunin resulted in the two polypeptides becoming coupled, indicating that cells other than hepatocytes may have the capacity to form chondroitin sulphate-containing links.

scholarly journals ELECTRON MICROSCOPY OF THE BURSA OF FABRICIUS OF THE EMBRYONIC CHICK WITH PARTICULAR REFERENCE TO THE LYMPHO-EPITHELIAL NODULES

1962 ◽  
Vol 13 (1) ◽  
pp. 127-146 ◽  
Author(s):  
G. Adolph Ackerman
Keyword(s):  
Endoplasmic Reticulum ◽  
Epithelial Cells ◽  
Embryonic Development ◽  
Golgi Complex ◽  
Bursa Of Fabricius ◽  
Cortical Region ◽  
Electron Microscopic ◽  
Submicroscopic Structure ◽  
Microscopic Studies ◽  
Pass Through

Electron microscopic studies of the bursa of Fabricius during the 15th and 16th day of embryonic development in the chick have shown the following findings in the submicroscopic structure of the cellular elements of the lympho-epithelial follicles. In the medulla, basal endodermal epithelial cells undergo mitosis and differentiation into lymphoblasts. During this transformation, there is a reduction in the amount of rough endoplasmic reticulum, an increase in the number or ribosomes, and frequently an enlargement of the Golgi complex. As lymphoblasts differentiate into medium lymphocytes there is a loss of endoplasmic reticulum, a reduction in the number of ribosomes and in the size of the Golgi complex, as well as a decrease in the number and size of mitochondria and in the size of the cell and nucleus. Cytoplasmic processes of reticular-epithelial cells extend between proliferating lymphocytic cells. Desmosomes connect stellate reticular-epithelial and basal epithelial cells but are not present in lymphocytic cells. Nuclear blebbing and vesiculation are frequently observed in the various cell forms of the developing lympho-epithelial nodules. Although lymphocytes and lymphocytopoietic activities in the cortex are sparse during this stage of embryonic development of the bursa, transitional forms between mesenchymal cells and lymphoblasts have been encountered. In addition, lymphoblasts and/or undifferentiated epithelial cells occasionally may pass through the basement membrane from the medulla into the cortical region of the developing nodule. That lymphocytes in the bursa of Fabricius originate from both endodermal and mesodermal derivatives during embryonic development appears to be consistent with both light and electron microscopic observations.

scholarly journals AN ULTRASTRUCTURAL STUDY OF PLANT SPERMATOGENESIS

1968 ◽  
Vol 37 (2) ◽  
pp. 370-393 ◽  
Author(s):  
F. R. Turner
Keyword(s):  
Electron Microscopy ◽  
Golgi Apparatus ◽  
Ultrastructural Study ◽  
Light And Electron Microscopy ◽  
Mature Sperm ◽  
Basal Bodies ◽  
Animal Cells ◽  
Early Spermatid ◽  
And Behavior ◽  
Cytoskeletal System

Spermatogenesis in the charophyte Nitella has been followed in antheridia prepared for light and electron microscopy. The antheridial filament cells contain paired centrioles which are similar in structure and behavior to the centrioles of animal cells. In the early spermatid, the centrioles undergo an initial elongation at their distal ends and become joined by a spindle-shaped fibrous connection. At the same time, their proximal ends are closely associated with the development of a layer of juxtaposed microtubules which will form the microtubular sheath. The architectural arrangement of these microtubules suggests that they constitute a cytoskeletal system, forming a framework along which the mitochondria and plastids become aligned and along which the nucleus undergoes extensive elongation and differentiation. The microtubular sheath persists in the mature sperm. During mid-spermatid stages, the centrioles give rise to the flagella and concomitantly undergo differentiation to become the basal bodies. The Golgi apparatus goes through a period of intensive activity during mid-spermatid stages, then decreases in organization until it can no longer be detected in the late spermatid. An attempt is made to compare similarities between plant and animal spermiogenesis.

The passage of staphylococci through the bovine teat canal

1968 ◽  
Vol 35 (3) ◽  
pp. 399-406 ◽  
Author(s):  
D. Forbes
Keyword(s):  
Staphylococcus Aureus ◽  
The Other ◽  
Intramammary Infection ◽  
Milk Samples ◽  
The Third ◽  
Colony Forming Unit ◽  
Before And After ◽  
Efficient Machine ◽  
Pass Through ◽  
Teat Canal

SummaryIn order to determine how bacteria pass through the teat canal into the teat sinus, milk samples were taken by syringe, through the teat wall, from 12 quarters of 7 cows, before and after each milking for up to 16 days. Three of the teat canals were naturally infected before the start of the experiment and the remainder were artificially infected with Staphylococcus aureus by the Hadley–Wisconsin swab technique. In 3 of the quarters the inoculum was introduced into the teat sinus through the teat canal by the inoculation technique although the swabs were inserted only 3–5 mm into the canal. The other 9 of the 12 quarters were milked a total of 149 times during the experiment but only once was a colony-forming unit of the bacterium present in a teat canal infection isolated from the milk taken from the teat sinus after milking. One quarter developed an intramammary infection, the bacterium first being detected in the teat sinus prior to the third milking after inoculation of the teat canal. The invasion of the bacteria into the teat sinus therefore occurred between milkings. Staph. aureus persisted in teat canals between 5 and 32 or more milkings after inoculation. The experiment showed that bacteria in the teat canal are seldom refluxed into the residual milk in the teat sinus during correctly conducted milking with an efficient machine.

scholarly journals Development of Microfluidic Technology for the Extraction of Ions from Some Dye Samples for Pretreatment Prior Analysis

2019 ◽  
Vol 35 (5) ◽  
pp. 1574-1578
Author(s):  
Ahmed Mohamed Fallatah
Keyword(s):  
Physical Properties ◽  
Copper Nanoparticles ◽  
Membrane Surface ◽  
Sample Introduction ◽  
Cu Nanoparticles ◽  
Fast Green ◽  
Microfluidic Technology ◽  
Before And After ◽  
Prior Analysis

Two different dye samples Fast Green and Black T were subjected for extracting their ions using a novel methodology based on microfluidics using a membrane without Treatment and membrane coated with copper nanoparticles, which exploits the advantages of miniaturization for sample introduction and extraction of a range of ions through a membrane before and after treatment. The membrane coated with Cu nanoparticles increases the extracting efficiency to 96.3 and 91.62 for Fastgreen membrane and Black T membrane respectively. This due to the new and good physical properties of the membrane surface after coating with nanoparticles.

OBSERVATIONS ON TRANSPORT OF OVA IN THE OVIDUCT OF THE MOUSE

1968 ◽  
Vol 40 (3) ◽  
pp. 267-273 ◽  
Author(s):  
K. W. HUMPHREY
Keyword(s):  
Ciliated Cells ◽  
Glass Coverslip ◽  
Before And After ◽  
Pass Through ◽  
Peristaltic Contractions ◽  
A Current

SUMMARY The movement of ova in the excised mouse oviduct was observed before and after straightening of the tube and after compression under a glass coverslip. Ciliated cells were present only in the ampulla, and produced a current from the bursa to the ampulla. However, movement of ova in the dilated section of the ampulla was seen to be due solely to contractions of the walls. In the isthmus ova were found only in one or two adjacent loops. These were dilated and showed segmental contractions, producing pendular movements of the ova. Peristaltic contractions were only seen in loops containing ova and in the isthmus near the ampulla-isthmus junction; this may present adovarian movement of ova. In vivo, most ova pass through the isthmus in 12 hr. The sphincters at the ampulla-isthmus and isthmouterine junctions retain the ova for 24 and 30 hr. respectively of the 72 hr. spent in the tube.

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