Morphology of complex lymphoepithelial organs of the anal canal (“anal tonsil”) in the bottlenose dolphin,Tursiops truncatus

A complex of lymphoepithelial organs, the “anal tonsils,” is a consistent structure in the anal canal of the bottlenose dolphin, Tursiops truncatus. This complex occurs as a circumferential cluster of discrete tonsil like aggregations of lymphoid tissues, together with epithelial ducts (“crypts”) and occasional mucus secretory units in the extreme lower portion of the intestinal tract. These structures are concentrated in the segment lined by stratified squamous epithelium and extend for a variable distance cephalad from the anal aperture. The tonsils appear to be most active, judged by the amount of lymphoid tissue present, in young animals. Depletion of lymphocytes and cystic enlargement of the crypts, probably representing functional as well as morphological involution, is a consistent feature of older animals. © 1995 Wiley-Liss, Inc.     

Structure and composition of the oral mucous membrane on the lips and cheeks of the monkey,Macaca fascicularis

Summary In seven monkeys (6 Macaca fascicularis, 1 M. mulatta; 2.4±0.6 kg in weight) the labial and buccal mucosae were studied morphologically and quantitatively. Following fixation by perfusion, the upper and lower lips and entire cheeks were dissected free and processed for light-, scanning and transmission electron microscopy. Established programs (HISTOMEP, MUMANA II) and appropriate morphometric techniques were used to estimate, at the light-microscopic level, the epithelial thickness, the width of the combined lamina propria/submucosa, and the volumetric composition of the gland-containing portions of lip and cheek mucosae. The cheek epithelium was more than twofold thicker than the lip epithelium, on the average 0.46±0.04 and 0.21±0.02 mm, respectively, with no differences related to sex or topographical sites. The combined lamina propria/submuscosa was 1.32 ±0.19 and 1.50±0.26 mm in width in cheeks and lips, respectively. The main mucosal constituents at both sites were glandular and connective tissue, and lymph follicles associated with secretory ducts. In lips, the volume of plasma cells around gland acini correlated positively with the amount of lymphoid tissue present around topographically related ducts. It is suggested that the duct/ lymph follicle assembly may serve as a local antigen-recognition system.

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Zusammenfassung Die Lippen- und Wangenmukosa wurde an 7 Affen (6 M. fascicularis, 1 M. mulatta; 2,4±0,6 kg schwer) morphologisch und quantitativ untersucht. Nach einer Perfusionsfixation wurden Ober- und Unterlippen sowie ganze Wangen herauspräpariert und für Untersuchungen im Licht-, Raster und Transmissionselektronenmikroskop vorbereitet. Bestehende Programme (HISTOMEP, MUMANA II) und morphometrische Standardmethoden wurden verwendet, um lichtmikroskopisch die Epitheldicke, die Breite der kombinierten Lamina propria/Submukosa und die volumetrische Zusammensetzung der drüsenhaltigen Abschnitte der Lippen- und Wangenschleimhaut zu ermitteln. Das Wangenepithel war mehr als zweifach dicker als das Lippenepithel (0,46±0,04 und 0,21±0,02mm); die Epitheldicke war unabhängig von Geschlecht und Topographie. Die kombinierte Lamina propria/ Submukosa war im Wangenbereich 1,32±0,19, im Lippenbereich 1,50± 0,26 mm breit. Die Hauptelemente der Lippen- und Wangenschleimhaut sind Drüsen- und Bindegewebe sowie mit Ausführungsgängen assoziierte Lymphfollikel. In der Lippen-, nicht aber in der Wangenschleimhaut, ist das Volumen der die Drüsenacini umlagernden Plasmazellen positiv korreliert mit der Menge der Lymphfollikel an den benachbarten Ausführungsgängen. Es wird vermutet, daß das Ausführungsgang/Lymphfollikel-System zur lokalen Erkennung von Antigenen dienen könnte.

     

Germinal centers and the B-cell system

Summary The migration pattern of germinal center cells of the rabbit appendix was studied and compared with that of appendix dome cells, spleen cells, thymus cells and thoracic duct lymphocytes. To discriminate T-and B-cell migration pathways, normal or T-cell-depleted rabbits were used as donors. Cell suspensions were labeled in vitro with ³H-leucine followed by intravenous transfer. The migration of labeled cells in lymphoid organs was studied using autoradiography, particular attention being paid to the spleen of the recipient. B-cells from the appendix dome, spleen and thoracic-duct lymph migrate to primary follicles or the corona of secondary follicles via thymus-dependent areas of peripheral lymphoid organs. In contrast, a B-cell subpopulation from the germinal centers of the appendix migrates to the center of splenic primary follicles and into germinal centers. The migration of germinal center cells to splenic follicle centers is not enhanced by specific antigens. The migration properties of B-cells, possibly changing during differentiation, may be instrumental in the two types of immune reactions, i.e., plasma-cell reaction and germinal-center reaction.     

White pulp compartments in the spleen of the turtle Mauremys caspica

Summary The aim of the present study was to analyze the nature of lymphoid and non-lymphoid cellular components occurring in distinct histological compartments of the splenic white pulp of the turtle, Mauremys caspica, in order to define their possible correlations with those of the spleen of higher vertebrates, principally mammals. The white pulp of M.caspica consisted of 3 clearly distinguishable regions: (1) the periateriolar lymphoid sheath, and (2) the inner and (3) the outer zones of the periellipsoidal lymphoid sheath. Reticular cells intimately associated with reticular fibres constituted an extensive meshwork in the periarteriolar lymphoid sheath which housed principally Ig-negative lyphoid cells, mature and immature plasma cells, and interdigitating cells. A few Ig-positive cells were also present in the peripheral region of the periarteriolar lymphoid sheath. The inner and outer zones of the periellipsoidal lymphoid sheath were separated by a discontinuous layer of reticular cell processes. In the inner zone, surface Ig-positive lymphoid cells predominated as well as dendritic cells, resembling ultrastructurally the mammalian follicular dendritic cells, although no germinal centres were found in the turtle spleen. Macrophages, some cytoplasmic Ig-positive cells, and Ig-negative lymphoid cells appeared in the outer zone of the periellipsoidal lymphoid sheath. These results allow us to speculate on a phylogenetic relationship between the periarteriolar lymphoid sheath and the inner and the outer zones of the periellipsoidal lymphoid sheath of the spleen of M. caspica and the periarteriolar lymphoid tissue, the lymphoid follicles and the marginal zone, respectively, of the mammalian splenic white pulp.     

The epithelium overlying rabbit bronchus-associated lymphoid tissue does not express the secretory component of immunoglobulin A

Summary The epithelium associated with lymphoid aggregates in the bronchial tract (BALT) was studied in rabbits by immunohistochemistry using monoclonal antibodies against the secretory component (SC) of IgA. The normal bronchus epithelium was intensely labelled. In contrast, epithelium overlying the central parts of the follicles was negative. This specialized epithelium cannot participate in the SC-mediated transport of IgA, which might be a basis for the adherence and transport of microorganisms into the lymphoid tissue, thus initiating immune responses of the BALT.     

LYSOSOME FUNCTION IN THE REGULATION OF THE SECRETORY PROCESS IN CELLS OF THE ANTERIOR PITUITARY GLAND

The nature and content of lytic bodies and the localization of acid phosphatase (AcPase) activity were investigated in mammotrophic hormone-producing cells (MT) from rat anterior pituitary glands. MT were examined from lactating rats in which secretion of MTH¹ was high and from postlactating rats in which MTH secretion was suppressed by removing the suckling young. MT from lactating animals contained abundant stacks of rough-surfaced ER, a large Golgi complex with many forming secretory granules, and a few lytic bodies, primarily multivesicular bodies and dense bodies. MT from postlactating animals, sacrificed at selected intervals up to 96 hr after separation from their suckling young, showed (a) progressive involution of the protein synthetic apparatus with sequestration of ER and ribosomes in autophagic vacuoles, and (b) incorporation of secretory granules into multivesicular and dense bodies. The content of mature granules typically was incorporated into dense bodies whereas that of immature granules found its way preferentially into multivesicular bodies. The secretory granules and cytoplasmic constituents segregated within lytic bodies were progressively degraded over a period of 24 to 72 hr to yield a common residual body, the vacuolated dense body. In MT from lactating animals, AcPase reaction product was found in lytic bodies, and in several other sites not usually considered to be lysosomal in nature, i.e., inner Golgi cisterna and associated vesicles, and around most of the immature, and some of the mature secretory granules. In MT from postlactating animals, AcPase was concentrated in lytic bodies; reaction product and incorporated secretory granules were frequently recognizable within the same multivesicular or dense body which could therefore be identified as "autolysosomes" connected with the digestion of endogenous materials. Several possible explanations for the occurrence of AcPase in nonlysosomal sites are discussed. From the findings it is concluded that, in secretory cells, lysosomes function in the regulation of the secretory process by providing a mechanism which takes care of overproduction of secretory products.     

Postnatal development of mucosa-associated lymphoid tissues in chickens

Summary The postnatal development of chicken mucosa-associated lymphoid tissues of the eyes, lungs, and intestines were investigated with monoclonal antibodies specific for either all leucocytes, B lymphocytes, mononuclear phagocytes, IgM, IgG, or IgA. Attention has been paid to the relation of lymphoid infiltrates with their surrounding mucosae, the segregation into B-cell and T-cell areas, development of germinal centers, and secretory immunoglobulins. Abudant secretory IgM and IgA was detected in the epithelium of the Harderian glands in the orbits, even though they lacked large leucocyte infiltrates with germinal centers. Lymphoid tissues in the mucosae of lungs and intestines developed separate B-cell and T-cell areas. The proventriculus, Meckel's diverticulum, and Peyer's patches generally contained germinal centers from 12 weeks of age on. Because chickens as young as 2 weeks old had germinal centers in bronchus-associated lymphoid tissue and cecal tonsils, these areas were probably highly stimulated by antigens. Isotype-specific monoclonal antibodies were used to detect IgM-, IgG-, and IgA-bearing follicular cells in the same germinal center.     

Localization of a protein,immunologically similar to a sucrose-binding protein from developing soybean cotyledons,on the plasma membrane of sieve-tube members of spinach leaves

Immunocytochemical studies using antibodies raised against a 62-kDa membrane protein isolated from developing soybean (Glycine max (L.) Merr.) cotyledons were performed on leaf tissue of spinach (Spinacia oleracea L.). This 62-kDa protein was labeled by 6′-deoxy-6′-(4-azido-2-hydroxy)-benzamidosucrose (HABS), a photoaffinity sucrose analogue (K. G. Ripp et al., 1988, Plant Physiol.88, 1435–1445). Western-blot analysis of spinach plasma-membrane proteins indicated a cross-reactive polypeptide identical in molecular mass to that found in soybean. Indirect immunogold labeling of resin-embedded sections of fully expanded leaf tissue resulted in specific localization of colloidal gold on the sieve-tube plasma membrane. The label was uniform and, except for a few non-specific gold particles over the cell wall, all other cellular organelles and membrane systems were free of label. With the exception of occasional gold particles associated with the companion-cell plasma membrane, all other cell types of the leaf contained little or no label. Control sections treated with non-immune rabbit immunoglobulin-G were also essentially free of label. Immunogold labeling of young leaves, in which the phloem contained no mature sieve-tube members, were free of label for the 62-kDa protein. However, young leaf tissue in which mature or nearly mature sieve tubes could be identified, contained immunolabel associated with the sieve-tube plasma membranes. Similar results were obtained with mature leaf tissue of sugar beet (Beta vulgaris L.). The results of the immunocytochemical studies are consistent with the suggestion that the concentrating step in the phloem-loading process in this species may occur across the sieve-tube plasma membrane. This paper is dedicated to the memory of William A. Dungey     

Expression of human B-Cell specific receptor FCRL1 in healthy individuals and in patients with autoimmune diseases

The expression levels of the FCRL1 gene, which encodes a human B-cell surface receptor, were compared in healthy individuals and patients with autoimmune diseases. The expression levels were evaluated using DNA dot hybridization on membranes with spotted cDNA samples derived from blood-cell sub-populations of patients with autoimmune diseases. Quantification of the hybridization signals showed that FCRL1 expression in peripheral blood B-lymphocytes of patients with multiple sclerosis, lupus anticoagulants, Takayasu’s arteritis, and von Willebrand disease was significantly higher than in healthy individuals. Monoclonal and polyclonal FCRL1-specific antibodies that enable FCRL1 detection in Western blotting, immunohistochemistry, and flow-cytometry assays were generated. It was found that FCRL1 is expressed on the surfaces of mature CD19+ B-cells. In the tonsils, FCRL1-positive cells were located in the crypt area, i.e., in the mantle zone of secondary lymphoid follicles and among the cells of lymphoid epithelium. FCRL1-positive cells were also found in B-cell follicles of the spleen.     

Ultrastructure of sperm storage and male genital ducts in a male holocephalan, the elephant fish, Callorhynchus milii.

In chondrichthyes, the process of spermatogenesis produces a spermatocyst composed of Sertoli cells and their cohort of associated spermatozoa linearly arrayed and embedded in the apical end of the Sertoli cell. The extratesticular ducts consist of paired epididymis, ductus deferens, isthmus, and seminal vesicles. In transit through the ducts, spermatozoa undergo modification by secretions of the extratesticular ducts and associated glands, i.e., Leydig gland. In mature animals, the anterior portion of the mesonephros is specialized as the Leydig gland that connects to both the epididymis and ductus deferens and elaborates seminal fluid and matrix that contribute to the spermatophore or spermatozeugmata, depending on the species. Leydig gland epithelium is simple columnar with secretory and ciliated cells. Secretory cells have periodic acid-Schiff positive (PAS+) apical secretory granules. In the holocephalan elephant fish, Callorhynchus milii, sperm and Sertoli cell fragments enter the first major extratesticular duct, the epididymis. In the epididymis, spermatozoa are initially present as individual sperm but soon begin to laterally associate so that they are aligned head-to-head. The epididymis is a highly convoluted tubule with a small bore lumen and an epithelium consisting of scant ciliated and relatively more secretory cells. Secretory activity of both the Leydig gland and epididymis contribute to the nascent spermatophores, which begin as gel-like aggregations of secretory product in which sperm are embedded. Fully formed spermatophores occur in the ductus. The simple columnar epithelium has both ciliated and secretory cells. The spermatophore is regionalized into a PAS+ and Alcian-blue-positive (AB+) cortex and a distinctively PAS+, and less AB+ medulla. Laterally aligned sperm occupy the medulla and are surrounded by a clear zone separate from the spermatophore matrix. Grossly, the seminal vesicles are characterized by spiral partitions of the epithelium that project into the lumen, much like a spiral staircase. Each partition is staggered with respect to adjacent partitions while the aperture is eccentric. The generally nonsecretory epithelium of the seminal vesicle is simple columnar with both microvillar and ciliated cells.     

The early postnatal development of the primary immune response in TNP-KLH-stimulated popliteal lymph node in the rat

Summary The popliteal lymph nodes were removed from young rats of various ages five days after a single immunization with TNP-KLH in the hind footpads. Cryostat sections of the lymph nodes were investigated by means of enzyme and immunohistochemical techniques at the light-microscopical level.The presence and localization of anti-TNP antibody-containing cells were examined using a new technique to visualize specific antibodies. Moreover, the development of the lymph nodes following exogenous antigenic stimulation was compared with that of unstimulated lymph nodes.Specific antibody-containing cells could not be found before day 15 after birth, in rats immunized at day 10. From that time these lymphoid cells were located primarily at the border between cortex and medulla. Younger popliteal lymph nodes showed only aspecific immunoglobulin-containing lymphoid cells. With age, the number of specific antibody-containing cells tended to increase. These cells were more mature, according to morphological criteria and were located nearer the medulla.The first primary follicles were seen at day 19, as was the case in unstimulated animals. The first secondary follicles, containing germinal centers, were detected at day 23, whereas in unstimulated popliteal lymph nodes they were never found.Trapping of immune complexes could not be demonstrated before day 33 after birth. The later appearance of this phenomenon might be a consequence of the techniques applied to demonstrate specific antibody-containing cells.Abbreviations PLN popliteal lymph node - FDC follicular dendritic cell - IDC interdigitating cell - HEV high endothelial venule - TNP trinitrophenyl - KLH keyhole limpet hemocyanin - PBS phosphate-buffered saline - GCPC germinal center precursor cell - sIg surface immunoglobulin - cIg cytoplasmic immunoglobulin     

Developmental sequence for the copulatory organs of Kontikia mexicana with remarks on taxonomic significance (Turbellaria: Tricladida: Geoplanidae)

Five specimens, presumably representing different developmental stages of the land planarian Kontikia mexicana (Hyman, 1939), were used to reconstruct the development of the copulatory apparatus in this species. The results support the notion that Kontikia differs from the closely related Caenoplana in its possession of a penis papilla. In the earliest stage available, a penis papilla was absent and other components were not differentiated. In a late-juvenile condition, the gonopore, seminal vesicle, and ejaculatory duct were present. The short penis papilla appeared to arise in this stage by elongation of the terminal tissue around the ejaculatory duct and its separation from the antral wall. The female canal was guarded by an epithelial fold and the glandular duct was present. In the mature condition, the penis papilla was more elongate, and the secretory (prostatic) region of the ejaculatory duct was functional. The female canal, guarded by an epithelial fold, was well-developed with enlarged glandular duct but lacking the posterior diverticulum and the sperm storage system associated with the ovovitelline ducts known in Kontikia orana Froehlich, 1955.     

Low CXCL13 expression, splenic lymphoid tissue atrophy and germinal center disruption in severe canine visceral leishmaniasis

Visceral leishmaniasis is associated with atrophy and histological disorganization of splenic compartments. In this paper, we compared organized and disorganized splenic lymphoid tissue from dogs naturally infected with Leishmania infantum assessing the size of the white pulp compartments, the distribution of T, B and S100⁺ dendritic cells, using immunohistochemistry and morphometry and the expression of CCR7 and the cytokines, CXCL13, lymphotoxin (LT)-α, LT-β, CCL19, CCL21, TNF-α, IL-10, IFN-γ and TGF-β, using by real time RT-PCR. The lymphoid follicles and marginal zones were smaller (3.2 and 1.9 times, respectively; Mann-Whitney, P<0.02) in animals with disorganized splenic tissue in comparison to those with organized splenic lymphoid tissue. In spleens with disorganized lymphoid tissue, the numbers of T cells and S100⁺ dendritic cells were decreased in the follicles, and the numbers of B cells were reduced in both the follicles and marginal zones. CXCL13 mRNA expression was lower in animals with disorganized lymphoid tissue (0.5±0.4) compared to those with organized lymphoid tissue (2.7±2.9, both relative to 18S expression, P = 0.01). These changes in the spleen were associated with higher frequency of severe disease (7/12) in the animals with disorganized than in animals with organized (2/13, Chi-square, P = 0.01) splenic lymphoid tissue. The data presented herein suggest that natural infection with Leishmania infantum is associated with the impairment of follicular dendritic cells, CXCL13 expression, B cell migration and germinal center formation and associates these changes with severe clinical forms of visceral leishmaniasis. Furthermore the fact that this work uses dogs naturally infected with Leishmania infantum emphasizes the relevance of the data presented herein for the knowledge on the canine and human visceral leishmaniasis.     

Evidence of steroidogenesis in postovulatory follicles of the tilapia,Oreochromis mossambicus

Summary Postovulatory follicles of the tilapia, Oreochromis mossambicus, were examined with electron microscopy and enzyme histochemistry for evidence of steroid-hormone production. Light microscopy was also used to examine changes in the ovary with time after spawning. Electron microscopy detected the presence of smooth endoplasmic reticulum, lipid droplets, and mitochondria with tubular cristae in certain cells of the theca interna. These structures are suggestive of cells that synthesize steroid hormones. Granulosa cells also contained some smooth endoplasmic reticulum, along with an augmentation of Golgi complexes, vesicles, microvilli, and microfilaments within 5–7 days after spawning. Enzyme histochemistry demonstrated an intense reaction of 5, 3-hydroxysteroid dehydrogenase (3-HSD) in variably placed thecal cells up to 7 days after spawning. At this time, the thecal cells of vitellogenic oocyte follicles also began to show strong 3-HSD activity. During the first 7 days after spawning, there was an increase in young primary oocytes and recruitment of some of these to vitellogenic oocytes. By 10 days after spawning, certain thecal cells in the follicles of these vitellogenic oocytes showed an intense 3-HSD reaction, while the postovulatory follicular tissue demonstrated a weak reaction. This arrangement continued for the lifespan of the postovulatory follicular tissue. Postovulatory follicles had a lifespan of up to 25 days after spawning in females that continued to hold the developing fry inside their mouths, i.e., mouthbrooders. At 25 days after spawning, the postovulatory follicular tissue showed signs of degeneration with the presence of vacuoles and lysosomes. In females that ate the zygotes, therefore exhibiting no parental behavior, the postovulatory follicular tissue showed signs of degeneration at l0days after spawning. In these females, the next clutch of eggs also developed at a higher rate than in mouthbrooders.     

黄土区不同林龄刺槐人工林细根的衰老生理特征

以黄土高原刺槐人工林为研究对象,采用手工挖掘法,配合完整土块法获取根系样品,分析幼龄(11a),中龄(22a),成熟(34a)刺槐人工林细根活力、可溶性糖含量、可溶性蛋白含量和细胞膜透性等细根衰老生理指标的差异,为深入了解刺槐细根的生长和衰老机制提供参考。结果表明:(1)在生长季节,刺槐细根活力表现为,幼龄林成熟林中龄林,可溶性糖含量、可溶性蛋白含量随着林龄增大而增加,而细胞膜透性则随林龄的增加而减小。(2)随着根序增加,根活力和可溶性糖含量增加,而可溶性蛋白含量和细胞膜透性则呈波动式降低。这表明,在生长季节幼龄林细根较中龄林和成熟林更容易出现衰老,刺槐不同根序衰老具有顺序性,衰老先从1级根开始,然后是2级根和3级根。     

Crypt architecture of tonsilla lingualis in the monkey,Macaca fascicularis

Summary Crypts of the lingual tonsil were investigated in 10 male and female Macaca fascicularis by use of correlated light and scanning-electron microscopy. Counting of crypt openings provided an estimate of the total number of respective crypto-lymphatic units, which were found to range from 20 to 39. Crypt openings appeared in three distinct morphological varieties, i.e. circular, oval or slit-like. Tonsillar units existed individually or were arranged in a rosary fashion below a slit-like mucosal fold serving as a common exit. Although the crypt epithelium was generally non-keratinized, individual cells showing a surface pattern similar to that of the keratinized cells could be encountered. The crypt epithelium was frequently fragmented and showed heavy mononuclear cell infiltration and surface discontinuities, with lymphoid cells coming in contact with luminal contents. The crypt lumen either appeared as a simple epithelial invagination or existed as a complex, cavernous pouch with many blind-ending diverticula. The lumen contained a mixture of exfoliated epithelial cells, leucocytes and bacteria. The secretory ducts of the posterior lingual glands opened occasionally at various levels into the crypt lumina or independently to the exterior.     

In vitro stimulation and inhibition of steroid hormone release from postovulatory follicles of the tilapia,Oreochromis mossambicus

Summary Postovulatory follicles of the tilapia, Oreochromis mossambicus, were incubated with graded doses of salmon gonadotropin to identify the steroid hormones released by this tissue. In addition, the effects of either cytochalasin B or colchicine on steroid hormone release were studied. After the incubation, the tissue was examined by electron microscopy. Postovulatory follicles released testosterone and estradiol-17B in a dose-dependent manner with gonadotropin. There was no detectable release of progesterone or 17a-OH-progesterone. When stimulated with high doses of gonadotropin, the steroidogenic cells showed an increase in smooth endoplasmic reticulum, Golgi complexes, and lipid droplets. Also, microfilaments became arranged in orderly bundles and were found close to the numerous secretory vesicles and lipid droplets. Upon incubation with gonadotropin and either colchicine or cytochalasin B, the cells still appeared steroidogenic, but the filaments were not organized nor associated with vesicles or lipid droplets. Release of steroid hormone decreased significantly. Also in these tissues, vesicles were no longer numerous in the apical region of the granulosa cells, but were located primarily near smooth endoplasmic reticulum and Golgi complexes. This suggests that disruption of the cytoskeleton results in reduced steroid hormone synthesis or release.     

Ultrastructure of coelomic epithelium and coelomocytes of the starfish Asterias rubens L. in norm and after wounding

Samples of coelomic epithelium (CE) and coelomocyte suspension of intact and wounded starfish Asterias rubens L. were studied by electron microscopy. The CE was shown to be composed of three types of cells: flagellar (approximately 60%), secretory (approximately 3%), and myoepithelial (approximately 37%); flagellar and secretory cells form the CE apical surface. Secretory cells are represented by two subtypes, i.e., granular and mucous secretory cells. Myoepithelial cells are located in the basal zone of the epithelium. In 4–5% of cases, adjacent flagellar cells are separated by various sizes of intercellular gaps. These gaps seem to be lacunae left by the flagellar cells after their release into the coelomic cavity. The morphological pattern of the conversion of CE flagellar cells into coelomocytes was characterized. After a moderate wounding used in the present study, no significant structural alterations in the CE organization were revealed. In coelomocyte suspension, small rounded young coelomocytes (approximately 3%) and the larger mature coelomocytes (approximately 97%) were found. On the surface of one of the young coelomocytes, a flagellum was revealed. Surface of the mature coelomocytes forms processes of various size and structure; their cytoplasm contains lysosomes and phagocytic vacuoles of different size. After wounding, a coelomocyte activation was found that consisted of a sharp rise in the number and length of filopodia on their surface, as well as the formation of multicellular aggregates. The complex of ultrastructural data allows it to be suggested that the histogenesis of coelomocytes from CE flagellar cells is a process of cell transdifferentiation.     

Structure and development of the secretory cavities of Myrtus communis leaves

The structure and development of Myrtus communis L. secretory cavities has been studied in young and expanded leaves, using light and scanning electron microscope. Secretory cavities are continuously formed during leaf development, but in mature leaves the rhythm of their appearance shows steep decrease. Each secretory cavity is developed from a single epidermal cell, which undergoes a periclinal division followed by anticlinal and several oblique cell divisions. The lumen of the secretory cavity is initiated by cell wall separation, i.e., schizogenously. The secretory cells line the cavity, where the secreted material is collected. Secretory cavities are covered by modified epidermal cells, which do not seem to form any special aperture. Essential oils seem to be discharged after mechanical treatment of the leaf.     

The effect of ovarian follicle size on pituitary and ovarian responses to copulation in domesticated South American camelids.

The relation of ovarian follicle size to pituitary and ovarian responses to copulation was studied in domesticated South American camelids (llamas and alpacas). Females from each species were divided into four groups according to follicle size: small (4-5 mm), growing (6-7 mm), mature (8-12 mm), and regressing (10-7 mm). The pituitary response to copulation was determined by analysis of LH and FSH concentrations in plasma. The ovarian response to copulation was determined by ultrasonography and by analysis of estrone sulfate (follicular status) and pregnanediol glucuronide (luteal status) concentrations in urine. Females with small follicles (4-5 mm) released less LH after copulation than did those with larger follicles, and ovulation was not induced. Females with growing and mature follicles (7-12 mm) released LH in response to copulation that was adequate to induce ovulation and to initiate normal luteal activity. While copulation-induced LH release in females with regressing follicles was similar to that released in animals with growing and mature follicles, regressing follicles were luteinized instead of being ovulated. The luteal structure formed as a result of luteinization of follicles had a short life span, i.e., 5.1 days. Copulation-induced LH release was significantly higher in llamas vs. alpacas in animals with mature or regressing follicles, but not in those with small or growing follicles. Urinary estrone sulfate and pregnanediol glucuronide concentrations correlated positively with the presence of follicles and corpora lutea, respectively.