Gastrointestinal helminths of the lizard Chalcides ocellatus from Benghazi, Libya

Chalcides ocellatus, a scincid lizard, sampled during October 1998 to December 1999 from Benina (farmland) and Al-Kueffia (a rocky area) in Benghazi, Libya, was found to harbour three intestinal nematodes, Pharyngodon mamillatus, Thelandros alatus and Parapharyngodon micipsae, and an intestinal cestode, Oochoristica tuberculata. Thelandros alatus, P. micipsae and O. tuberculata were recorded for the first time in C. ocellatus. Parapharyngodon micipsae was detected in C. ocellatus from Benina and O. tuberculata from lizards in Al-Kueffia. The majority (87.6%) of C. ocellatus were infected with helminth parasites and the levels of infection were higher in males than in females but this difference was not significant. Pharyngodon mamillatus recorded the highest number of nematode parasites in C. ocellatus, although there was no relationship between the number of nematode parasites recovered and host density. In lizards infected with the cestode O. tuberculata, males had shorter snout-vent lengths than females. From a total of 153 C. ocellatus, 120 (78.4%) showed single and 14 (9.2%) showed mixed parasitic infections. Mixed infections between different species of nematodes were not observed.     

Further scanning electron microscope studies of lizard auditory papillae

The papillae basilares of 12 species of lizards from seven different families were studied by SEM. The iguanids, Sceloporus magister and S. occidentalis, have typical “iguanid type” papillae with central short-ciliated unidirectional hair cell segments and apical and basal long-ciliated bidirectional hair cell segments. These species of Sceloporus are unique among iguanids in that the bidirectional segments consist of but two rows of hair cells. The agamids, Agama agama and Calotes nigrolabius, have an “agamid-anguid type” papilla consisting of an apical short-ciliated unidirectional hair cell segment and a longer basal bidirectional segment. Agama agama is unusual in having a few long-ciliated hair cells at the apical end of the apical short-ciliated segment. The agamid, Uromastix sp., has an “iguanid type” papilla with a central short-ciliated unidirectional segment and apical and basal bidirectional segments. The anguid, Ophisaurus ventralis, has an “iguanid” papillar pattern with the short-ciliated segment centrally located. All the short-ciliated hair cells of the above species are covered by a limbus-attached tectorial network or cap and the long-ciliated hair cells, only by loose tectorial strands. The lacertids, Lacerta viridis and L. galloti, have papillae divided into two separate segments. The shorter apical segment consists of opposingly oriented, widely separated short-ciliated cells covered by a heavy tectorial membrane. The apical portion of the longer basal segment consists of unidirectionally oriented hair cells, while the greater part of the segment has opposingly oriented hair cells. The xantusiids, Xantusia vigilis and X. henshawi, have papillae made up of separate small apical segments and elongated basal segments. The apical hair cells are largely, but not exclusively, unidirectional and are covered by a heavy tectorial cap. The basal strip is bidirectional and the hair cells are covered by sallets. The kinocilial heads are arrowhead-shaped. The papilla of the cordylid, Cordylus jonesii, is very similar to that of Xantusia except that the apical segment is not completely separated from the basal strip. The papilla of the Varanus bengalensis is divided into a shorter apical and a longer basal segment. The hair cells of the entire apical and the basal three quarters of the basal segment are opposingly oriented, not with reference to the midpapillary axis but randomly to either the neural or abneural direction. The apical quarter of the basal segment contains unidirectional, abneurally oriented hair cells. The entire papilla is covered by a dense tectorial membrane. The functional correlations of the above structural variables are discussed.     

The endocrine pancreas of a squamate reptile,the desert lizard (Chalcides ocellatus)

Summary The endocrine pancreas of the desert lizard (Chalcides ocellatus) was investigated histologically and immunocytochemically. The endocrine tissue was concentrated in the dorsal lobe, where it constituted about 7% of the total volume. In the ventral lobe the endocrine tissue formed approximately 1% of the total volume. Four endocrine cell types were observed in the pancreas of this species, namely insulin-, glucagon-, somatostain- and pancreatic polypeptide (PP)-immunoreactive cells. The volume occupied by these cells was 1, 1, 0.6 and 0.3% of the total volume of the pancreas, respectively. Insulin-immunoreactive cells were located in the islet centre and comprised 3% of dorsal and 0.2% of the ventral lobe volume. Glucagon cells occurred at the islet periphery and amounted to 3 and 0.2% of the volume of the dorsal and ventral lobes, respectively. Somatostatin-immunoreactive cells were located at the islet periphery as well as in between the exocrine parenchyma. They constituted 1 and 0.2% of the volume of the dorsal and ventral lobes, respectively. PP-immunoreactive cells occurred mainly among the exocrine parenchyma as solitary cells. They formed only 0.03% of the volume of the dorsal lobe. The corresponding figure in the ventral lobe was 0.6%.     

Factors affecting helminths community structure of the Egyptinan lizard Chalcides ocellatus (Forskal, 1775)

The variation in the component community structure of intestinal helminths in the lizard Chalcides ocellatus (Forskal, 1775) was studied in relation to the seasonal variation and host weight and sex. 120 lizards were collected seasonally during year 2004, from Al Firdan, Ismailia governorate, Egypt. The helminths community consisted of six species (five nematodes and one cestode). The various helminths differed according to host sex. The prevalence of total helminths infection was 67.6 % while the prevalences of Thelandros schusteri, Pharyngodon mamillatus, Parapharyngodon bulbosus, Cosmocerca vrcibradici, Spauligodon petersi and Oochoristica maccoyi were 43.4%, 3.9 %, 13.2%, 5.3%, 6.6%, and 14.3%, respectively. The results showed that the season was the main factor affecting infracommunity species richness and parasite abundance. Moreover, there was interaction between season and host sex on abundance of P. bulbosus. The prevalence of intestinal helminths varied significantly in relation to host weight classes and sex in some species. Helminths abundance and intensity were independent from host sex. In addition, correlations were found between total helminths abundance and host weight. In conclusion, the helminths community of C. ocellatus was depauperate and the influence of the studied factors varied from species to another one. We cannot say if the low species richness and infection rates observed in the present study are typical of the host species or if they are due to characteristics of the study area, since no available data on parasite assemblages exist for other C. ocellatus populations.     

Ontogeny of hemopoietic and lymphopoietic tissues in the lizard Chalcides ocellatus (Reptilia,Sauna, Scincidae)

The first and major blood-forming organ to develop in the viviparous lizard Chalcides ocellatus is the yolk sac, which exhibits prominent erythropoietic activity from as early as stage 21 through birth (stage 41). Myeloid cells and megakaryocytes are produced in the yolk sac from stage 23 onward. During lizard embryogenesis hemopoietic activity is also observed in spleen and bone marrow but in neither kidney nor liver. Cells capable of giving rise to lymphocytes both in vivo and in vitro are first found in the thymus at stage 35. Active lymphopolesis in thymus and spleen begins at stages 36 and 39, respectively. In contrast, the gut-associated lymphoid aggregates are not evident before birth.     

Light and electron microscope studies on the fruiting bodies of Chondromyces crocatus

Summary The fruiting bodies of Chondromyces crocatus have been examined by both light and electron microscopy. The cysts are bounded by a discrete layer of dense slime enclosing a material of lesser density in which the closely packed resting cells are embedded. The latter, in contrast to the microcysts of other myxobacters, are not enclosed in individual slime capsules. Young resting cells commonly contain numerous mesosomes while older resting cells are characterized by what appear to be large lipid granules.The slime stalk consists largely of a system of vertical, parallel empty tubules through which the cells have migrated during fruiting body development.Supported by grant number A 1022 from the National Research Council of Canada.     

The endocrine pancreas of a squamate reptile, the desert lizard (Chalcides ocellatus). A histological and immunocytochemical investigation

The endocrine pancreas of the desert lizard (Chalcides ocellatus) was investigated histologically and immunocytochemically. The endocrine tissue was concentrated in the dorsal lobe, where it constituted about 7% of the total volume. In the ventral lobe the endocrine tissue formed approximately 1% of the total volume. Four endocrine cell types were observed in the pancreas of this species, namely insulin-, glucagon-, somatostatin- and pancreatic polypeptide (PP)-immunoreactive cells. The volume occupied by these cells was 1, 1, 0.6 and 0.3% of the total volume of the pancreas, respectively. Insulin-immunoreactive cells were located in the islet centre and comprised 3% of dorsal and 0.2% of the ventral lobe volume. Glucagon cells occurred at the islet periphery and amounted to 3 and 0.2% of the volume of the dorsal and ventral lobes, respectively. Somatostatin-immunoreactive cells were located at the islet periphery as well as in between the exocrine parenchyma. They constituted 1 and 0.2% of the volume of the dorsal and ventral lobes, respectively. PP-immunoreactive cells occurred mainly among the exocrine parenchyma as solitary cells. They formed only 0.03% of the volume of the dorsal lobe. The corresponding figure in the ventral lobe was 0.6%.     

Changes in ovarian follicles and in vitro sex hormone release in the lizard Podarcis sicula sicula

An in vitro superfusion method was used to test sex hormone release from different kinds of ovarian follicle (growing follicles, postovulatory follicles, and atretic follicles) in the lizard Podarcis sicula sicula. Sex hormone output changes with the stage of follicle evolution and sexual cycle. Previtellogenetic follicles prevail in early-spring quiescent ovaries and secrete mainly progesterone, which is probably utilized at that phase to delay ovarian resumption. In the active ovary, progesterone output from previtellogenetic follicles decreases, whereas vitellogenetic follicles produce a significant amount of 17β-estradiol, which is necessary for sustaining vitellogenin synthesis by the liver and oviduct growth. As follicles become ripe, progesterone production is resumed, and it increases in young postovulatory follicles. This is in line with the functions assigned to the hormone at that phase of the sexual cycle, i.e., the induction of oocyte maturation and the regulation of egg retention in the oviduct. Postovulatory follicles can also synthetize 17β-estradiol. After oviposition, this hormone, which is secreted by the old postovulatory follicles, can reinitiate vitellogenin synthesis, allowing the development of a new oocyte set. Our data confirm that active, although ephemeral, corpora lutea are also formed in oviparous species. A limited contribution to ovarian sex steroid production derives also from atretic follicles, at least at the early stages of the breeding cycle. © 1993 Wiley-Liss, Inc.     

Light and electron microscope studies of effects of 50 Hz electromagnetic fields on preincubated chick embryo

We investigated the effects of an electromagnetic field (EMF) of 50 Hz, 1.33-7.32 mT on sections of preincubated white leghorn chicken embryos using light, SEM and TEM microscopes. Five hundred healthy, fresh, and fertilized eggs (55-65 g) were divided into three groups of experimental (n = 18-20), control (n = 60), and sham (n = 50). Experimental eggs (inside the coil) were exposed to 15 different intensities (1.33-7.32 mT) for morphological surveys and to the known most effective intensities for light, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) studies. Sham groups were located inside the same coil with no exposure for 24 h before incubation. Control, sham, and experimental groups were then incubated in an incubator (38 +/- 0.5 degrees C, 60% humidity) for 4 days. At the end of this period, embryos were removed from their shells, prepared for morphometric, light, and SEM/TEM studies. Results of light microscopic studies (serial sections, 6mu) and morphometric data showed significant differences between different groups (P < 0.005). Larger and abnormal brain cavities, spina bifida, monophthalmia, microphthalmia, anophthalmia, and growth retardation were shown on SEM. TEM sections demonstrated that the nucleus was condensed, the nuclear envelope disappeared, and mitochondria degenerated. Golgi apparatus and endoplasmic reticulum were the least affected organelles. The Telencephlon was the most affected region, and the retina was altered more than the lens. We conclude that EMFs affect the brain, especially the Telencephalon and eye of preincubated-exposed chick embryo at the morphological and cellular level, nuclei are the most affected part, and our data agrees with "Ubeda's windows effects" of EMFs on preincubated chick embryos.     

Light and electron microscope immunocytochemical localization of 5- and 12-lipoxygenases and cyclooxygenase enzymes in human granulosa cells from preovulatory follicles

Cellular and subcellular distribution of 5- and 12-lipoxygenases and cyclooxygenase enzymes were investigated in human granulosa cells from preovulatory follicles using light and electron microscope immunocytochemistry. The results demonstrated that all three enzymes are present in granulosa cells but not in minor contaminating red blood cells. While the distribution of cyclooxygenase and 12-lipoxygenase was relatively uniform among the granulosa cells, 5-lipoxygenase was not uniformly distributed among these cells. All three enzymes are present in microvillus plasma membranes, rough endoplasmic reticulum, cytoplasm, nuclear membranes and chromatin. In summary, 5- and 12-lipoxygenases and cyclooxygenase enzymes, which catalyze the transformation of arachidonic acid into different eicosanoids, are present in several subcellular organelles including nuclei of granulosa cells from preovulatory follicles.