Kinetics of spermatogenesis in the Mongolian gerbil (Meriones unguiculatus)

The Mongolian gerbil (Meriones unguiculatus) is a small rodent native to the arid regions of Mongolia and Northeastern China. The present study provides descriptions of both the cellular associations of the seminiferous-epithelium cycle and relative frequencies of stages in the gerbil. Based on the development of the acrosomic system and the nuclear morphology changes using the PAS-H staining technique, the transformation of spermatids into spermatozoa was divided into 15 steps. The first 12 steps were used to identify 12 stages or cellular associations and the other three steps were spread among the first six stages of the cycle of the seminiferous epithelium. The relative frequencies found for stages I through XII were: 13.15; 8.06; 8.98; 6.48; 5.37; 6.71; 7.36; 7.45; 7.27; 5.83; 11.53 and 11.81, respectively. Stage I had the highest frequency while stage V proved the lowest frequency among the XII stages. The pattern of spermatogenesis is similar to those of rodents used as laboratory animals. The present description is the first for this rodent and provides the foundation for a variety of future studies of the testis in this animal. © 2002 Elsevier Science Ltd. All rights reserved.

Ultrastructure of the salivary glands of Pachycondyla (=Neoponera) villosa (Fabricius) (Formicidae: Ponerinae): Functional changes during the last larval instar

The cells of secretory region of the salivary glands of Pachycondyla (=Neoponera) villosa at the time of enzyme production presents the basal cellular membranes profusely folded and the intercellular junctional membranes present a few enlarged spaces. The rough endoplasmic reticulum and the Golgi bodies shift from being flat and small vesicular cisternae to enlarged vesicular cisternae according to the cell physiological state and characterize an asynchronic cell cycle. Enzymes are released into the lumen by microapocrine secretion. The stage of silk production is detected after a behavioral act, when the nurse worker separates the mature larva. At this time, the salivary gland cells present only one physiological state (synchronized secretory cycle): this state was characterized by basal cellular membrane poorly folded, intercellular junctions presenting some small spaces, rough endoplasmic reticulum compounded by flat cistenae, enlarged Golgi bodies with fibrous material inside and a few secretory vesicles containing silk, which undergo exocytosis. The silk in the lumen shows 2 forms: tactoid and flocculent material.

Spermiophagy in the spermatheca of Melipona bicolor lepeletier, 1836 (Hymenoptera, Apidae, Meliponini)

The presence of spermatozoa in vesicles in the cytoplasm of the epithelial cells that constitute the spermathecal wall of Melipona bicolor queen (Meliponini) is discussed in relation to the organ structure. The epithelial wall is lined by an apparently continuous cuticle in the luminal surface that should be a non-transposable barrier to the luminal spermatozoa. However, some spermatozoa were seen crossing the cuticle through interruptions that was first interpreted as sectioning defects. Nevertheless, the sperm cells in well-structured cytoplasmic vesicles, bound by membranes and sometimes associated to multivesicular bodies, as well as cytoplasmic structures representative of intracellular digestion and the occurrence of the phenomenon in two of the three spermathecae studied, suggest a real spermiophagic hole in the spermathecal epithelial cells.

The ultrastructure of the intestinal epithelium in Oreochromis niloticus on a diet with different concentrations of zinc

The effects of diets with variable zinc levels on the midgut epithelial cells were studied in Oreochromis niloticus L. One hundred and twenty fry of tilapia were apportioned into 4 experimental groups (I, II, III and IV groups), with 30 fish in each treatment, 5 replicate aquaria per treatment containing 6 fish each. The animals of the 4 groups were fed with isonitrogenous (30% crude protein) and isoenergetic (3000 Kcal/Kg of digestible energy) diets with increasing quantities of zinc (44.59; 149.17; 309.93; 599.67 mg Zn/kg of diet), twice a day, for 93 days. Three fish from each group were sacrificed at 36, 66 and 93 days and samples of midgut were removed for ultrastructural analysis. After 93 days of treatment, 3 animals of each experimental group were used for the analysis of zinc concentration by atomic absorption spectrophotometry. The comparative relative index (CRI) revealed that the animals in groups II, III and IV contained, respectively, 1.99%, 34.67% and 22.78% more zinc than the mean concentration in animals from group I. The ultrastructural analysis showed enterocytes with swelling of smooth surfaced endoplasmic reticulum and dilated mitochondria with variable matrix rarefaction and cristae number reduction in the fish exposed to 599.67 mg Zn/Kg of diet at 66 and 93 days of treatment.

Glandular dots of Caesalpinia echinata Lam. (Leguminosae): Distribution, structure and ultrastructure

The structure and ultrastructure of immature to fully mature glandular dots in the leaf, floral organs and fruit, and their secretion components were described in Caesalpinia echinata Lam. (Leguminosae) for the first time. Data showed that glandular dots were groups of idioblasts with contents that reacted positively for both lipophilic and hydrophilic substances. Idioblasts originated from successive divisions of the ground meristem cells or mesophyll cells of an ovary of a fertilized flower. Following division, cells enlarged, the cytoplasm became denser and its content became full. No idioblasts were observed after fruit sclerification. Besides these mixed-content idioblasts, some cells in the sepals, petals and mesocarp were found to contain phenolic compounds, which probably represent a kind of constitutive defense mechanism, once the flowers and fruits become highly fitness-valued parts of the plant and can be commonly attacked. The contents of the idioblasts are released as the growth rate of the embryo increases, indicating that the plant probably diverts the precursors of secondary metabolites into the primary metabolism, at this critical time of embryo development.

Cryopreservation of dog spermatozoa: Effect of bovine serum albumin on acrosomal integrity and pregnancy rates after artificial insemination

The objective of the present study was to compare the in vitro and in vivo profile of frozen dog semen with Tris-bovine serum albumin (TB) and Tris-egg yolk (TE) extenders. Twenty dogs were used as donors. Each dog was stimulated by penile massage and only the sperm-rich fraction was collected weekly until 40 ejaculates were obtained. After macroscopic and microscopic analysis, equal parts of each ejaculate were diluted with TB and TE by the one-step method at 37 °C. The semen was added to 0.5-mL French straws which presented normal characteristics before freezing and after thawing. Acrosomal integrity was evaluated by double Trypan blue-Giemsa staining, in which alive intact (LI), alive reacted (LR), dead intact (DI) and dead reacted (DR) spermatozoa, were identified by the time of thawing and up to 4 h of incubation at 39 °C, the TE being significantly superior to TB (P<0,01) in the LI and LR variables. The TB being significantly superior to TE (P<0,01) in the DR variable. Female dogs in natural heat were submitted to artificial insemination, 20 receiving TE-semen and 20 receiving TB-semen with the Osiris probe (IMV, L'Aigle, France) and the numbers indicate that TE was significantly better than TB (P<0,01) to pregnancy rate and number of puppies/delivery. We concluded from this study, that TE was better than TB, because this, induced an eady acrossome reaction in dog's sperm.

Seleção de espermatozoides para ICSI

The application of assisted reproduction techniques has provided help to many men seeking to father a child, although the current success of these procedures remains suboptimal. Today some protocols allow sperm to be selected according to their ultrastructural morphology or surface molecular characteristics. On the other hand, successful human reproduction relies partly on the inherent integrity of sperm DNA. Therefore, it is now necessary to improve the safety of the sperm selection method. It is urgent to optimize procedures to isolate spermatozoa for ICSI with low risk of DNA damage. In recent years, two technologies have attracted the attention of specialists as methods capable of identifying a spermatozoon with low risk of DNA damage: Ultrastructural morphology sperm selection at high magnification and sperm head birefringence selection. This review analyses these two technologies. © Todos os direitos reservados a SBRA - Sociedade Brasileira de Reprodução Assistida.

Ultrastructure of sheep primordial follicles cultured in the presence of indol acetic acid, EGF, and FSH

The aim of this study was to investigate the ultrastructural characteristics of primordial follicles after culturing of sheep ovarian cortical slices in the presence of indol acetic acid (IAA), Epidermal Growth Factor (EGF), and FSH. To evaluate ultrastructure of primordial follicles cultured in MEM (control) or in MEM containing IAA, EGF, and FSH, fragments of cultured tissue were processes for transmission electron microscopy. Except in the control, primordial follicles cultured in supplemented media for 6d were ultrastructurally normal. They had oocyte with intact nucleus and the cytoplasm contained heterogeneous-sized lipid droplets and numerous round or elongated mitochondria with intact parallel cristae were observed. Rough endoplasmic reticulum (RER) was rarely found. The granulosa cells cytoplasm contained a great number of mitochondria and abundant RER. In conclusion, the presence of IAA, EGF, and FSH helped to maintain ultrastructural integrity of sheep primordial follicles cultured in vitro. © 2011 Evelyn Rabelo Andrade et al.

Effect of roscovitine and cycloheximide on ultrastructure of sheep oocytes

It is believed the temporary meiosis arrest with roscovitine or cycloheximide may improve the in vitro developmental competence of oocytes in different animal species. However, little is known about the effects of these inhibitors on ultrastructure of ovines cumulus-oocyte complexes (COCs). The aim of this study was to evaluate the progression of cytoplasmic maturation and the ultrastructural changes in sheep COCs exposed to roscovitine or cycloheximide, at acceptable concentrations. COCs were in vitro cultured for 24. h in maturation medium (control group) containing 100 μM roscovitine or 1 μg/mL cycloheximide (treatment groups). After this time, some COCs were cultured for further 22. h in inhibitor-free medium. The ultrastructure organization of COCs was evaluated by transmission electron microscopy before (immature group) and after in vitro culture for 24 and 46. h. As expected, signs of immaturity and maturity were observed in immature and control groups, respectively. In treatment with roscovitine, there were cumulus cells degeneration, swelling of mitochondrias, few cortical granules and many vesicles with electron-dense material. However, in cycloheximide treatment there were not signs of degeneration or cellular senescence. Metabolic units and mitochondrial pleomorphism were found in all experimental groups. These evidences demonstrate that roscovitine promoted irreversible ultrastructural changes while cycloheximide did not affect the cytoplasmic maturation. However, the implications on embryo development are still unclear. © 2012 Elsevier B.V.

The reproductive cycle of the male sleep snake Sibynomorphus mikanii (Schlegel, 1837) from southeastern brazil

This study describes the male reproductive cycle of Sibynomorphus mikanii from southeastern Brazil considering macroscopic and microscopic variables. Spermatogenesis occurs during spring-summer (September-December) and spermiogenesis or maturation occurs in summer (December-February). The length and width of the kidney, the tubular diameter, and the epithelium height of the sexual segment of the kidney (SSK) are larger in summer-autumn (December-May). Histochemical reaction of the SSK [periodic acid-Schiff (PAS) and bromophenol blue (BB)] shows stronger results during summer-autumn, indicating an increase in the secretory activity of the granules. Testicular regression is observed in autumn and early winter (March-June) when a peak in the width of the ductus deferens occurs. The distal ductus deferens as well as the ampulla ductus deferentis exhibit secretory activities with positive reaction for PAS and BB. These results suggest that this secretion may nourish the spermatozoa while they are being stored in the ductus deferens. The increase in the Leydig cell nuclear diameter in association with SSK hypertrophy and the presence of sperm in the female indicate that the mating season occurs in autumn when testes begin to decrease their activity. The peak activity of Leydig cells and SSK exhibits an associated pattern with the mating season. However, spermatogenesis is dissociated of the copulation characterizing a complex reproductive cycle. At the individual level, S. mikanii males present a continuous cyclical reproductive pattern in the testes and kidneys (SSK), whereas at the populational level the reproductive pattern may be classified as seasonal semisynchronous. © 2012 Wiley Periodicals, Inc.

Effect of Hot Air Drying on Ultrastructure of Crambe Seeds

This study was conducted to evaluate the morphologic modifications in tissues of the fruit and seed of the crambe (Crambe abyssinica Hochst. Ex R.E. Fr.) after drying at different temperatures. Fruits with a water content of 0.38 kg water/kg dry matter were harvested and manually homogenized. Drying was accomplished at 35, 45, 60, 75, and 90°C and at 21,9,7,5, and 2% relative humidity, respectively. After drying, the structure of the pericarp and tegument of the seed were evaluated and the embryo was removed from the fruit/seed for morphological analysis (structural and ultrastructural and the histolocalization of reserve substances). Drying at different temperatures did not affect the cellular structure of the tissues composing the pericarp of the fruits, but it disorganized the structure of the seed tegument. The cells of the tegument and cotyledons presented a contraction in their volumes. The lowest contractions in the cellular volumes of both the tegument and cotyledons occurred after drying at 35 and 45°C. The cytoplasm of the cotyledon cells contains oil drops and the protein bodies contain protein granules and starch grains. There were no changes in the cellular walls of the embryos of the fruits dried at different temperatures; however, ungluing of the medium lamella occurred. This damage occurred with greater intensity after drying at temperatures above 60°C. The form of the oil drops in the cytoplasm of the cotyledon cells was altered after drying. At temperatures above 60°C, the drops broke up and coalesced. After drying at 45 and 60°C, the form of some protein bodies was altered, whereas at 75 and 90°C coalescence of the protein bodies occurred in some cells. It was concluded that the identified alterations can affect the physiologic quality of crambe seeds. © 2013 Copyright Taylor and Francis Group, LLC.