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G Macchiarelli

Publications and source records attributed to G Macchiarelli.

At least 19 recordsLinked to original sources
PubMed2006

Ultrastructure of human mature oocytes after slow cooling cryopreservation using different sucrose concentrations.

BACKGROUND: We studied the ultrastructural characteristics of human mature oocytes frozen/thawed (F/T) using different concentrations of sucrose. Fresh human mature oocytes were used as controls. METHODS: The oocytes (n = 48) were fixed in 1.5% glutaraldehyde at sampling (n = 16) or after freeze/thawing performed using a slow cooling method with propane-1,2-diol 1.5 mol/l and sucrose at either 0.1 mol/l (n = 16) or 0.3 mol/l (n = 16) in the freezing solution. The oocytes were then processed for electron microscopy observations. RESULTS: Fresh and F/T oocytes belonging to both study groups were regularly rounded in sections, with a homogeneous cytoplasm and an intact zona pellucida (ZP). Organelles (mainly mitochondria-smooth endoplasmic reticulum aggregates and mitochondria-vesicle complexes) were abundant and uniformly dispersed in the ooplasm. The amount and density of cortical granules appeared to be abnormally reduced in some F/T samples, independently of the sucrose concentration in the freezing solution: this feature was frequently associated with an increased density of the inner ZP, possibly related to the occurrence of zona 'hardening'. Furthermore, slight to moderate microvacuolization was revealed in the ooplasm of some F/T oocytes, particularly in those treated with sucrose 0.3 mol/l. CONCLUSIONS: Freeze/thawing procedures are associated with ultrastructural alterations in specific oocyte microdomains, presumably linked to the reduced developmental potential of mature cryopreserved oocytes. Further work is needed to determine whether or not a high concentration of sucrose plays a role, at least in part, in producing the above alterations.

Adult↗
PubMed2006

Meiotic spindle configuration is differentially influenced by FSH and epidermal growth factor during in vitro maturation of mouse oocytes.

BACKGROUND: To ascertain whether different hormonal treatment protocols could affect metaphase II (MII) spindle morphology, meiotic spindle organization was detected in prepubertal mouse oocytes matured under conditions allowing spontaneous, FSH- or epidermal growth factor (EGF)-dependent meiotic maturation. METHODS: Oocyte-cumulus complexes (OCCs) were matured either spontaneously (control; n=270) or in the presence of hypoxanthine (Hx) plus FSH (n=400) or EGF (n=370). Spindles were detected by immunofluorescence analysis. In vivo ovulated (IVO) oocytes were processed similarly. RESULTS: IVO oocytes displayed spindles underlying the oolemma and with focused poles marked by spots of gamma-tubulin, whereas the majority (89%) of control oocytes had barrel-shaped spindles, positioned away from the oolemma, and with gamma-tubulin distributed along microtubules. Similar configuration/localization was found in 85% of the oocytes matured in vitro in the presence of Hx and FSH. In the presence of Hx-EGF, 35% of the oocytes showed spindles with an IVO-like configuration, although gamma-tubulin was homogeneously distributed throughout microtubules. Independently of spindle shape, 52% of EGF-stimulated oocytes had spindles positioned near the oolemma, in comparison to just 24% of FSH-treated and 13% of control oocytes. CONCLUSIONS: These results indicate that FSH and EGF can differently affect meiotic spindle morphology, and that EGF might be a stronger contributor than FSH to the acquisition of oocyte competence.

Animals↗
PubMed2005

Three-dimensional distribution of the collagen fibers in the submucosa of the swine terminal ileum.

Collagen has an important role in controlling mechanical function and physiopathology of intestinal wall. Swine small intestine may be used as biomaterial source for tissue repairing. Changes of collagen arrangement and three-dimensional (3D) distribution may be related to the dissimilar biomechanical proprieties showed by different intestine tracts. 3D spatial distribution of collagen bundles of swine submucosal terminal ileum (SSTI) was studied by a correlated analysis of light (LM) and scanning electron microscopy (SEM) of NaOH macerated samples. Bundles of collagen fibers were greatly represented in the submucosa at the mesenteric border and also extended along the longitudinal folds beneath mucosa layer. Polarized LM of picrosirius stained samples evidenced yellow and red fibers (type I collagen), and green fibers (type III collagen). Silver-impregnated sections showed predominant brown-stained fibers and, in a smaller amount, black-stained ones. By SEM submucosal collagen, isolated by NaOH maceration, appeared arranged in wide bundles forming a complicated 3-D network. The bundles presented a sinuous course, opened and closed repeatedly forming meshes fashioned in a regular net. These observations originally demonstrated that 3-D distribution of SSTI collagen is different from that observed in other gut segments and species. The arrangement of SSTI collagen fibers that we observed seems to be morphofunctionally adjusted to provide appropriate resistance to mechanical forces and to assure compliance to deformations induced by intestinal wall motion. The studies for selection of optimal intestinal patches for surgical replacement should take into consideration the basic morphological evaluation of parietal collagen 3D distribution.

Animals↗
PubMed2005

Short-term patency of 1 mm diameter PTFE prosthesis: an angiographic, Doppler-flowmetric and morphological experimental study.

Expanded polytetrafluoroethylene (PTFE) prostheses may be used in peripheral vascular surgery. Due to contradictory results on patency rate and neointimal formation, the effectiveness of this kind of prosthesis in small caliber artery reconstruction is still under discussion. In order to evaluate the effectiveness of this technique 1 mm internal diameter PTFE prosthesis (fibril length 35 microm) interposed in rabbit femoral artery, for 15 and 30 days, were studied functionally and morphologically. Doppler was performed during surgery, at day 2, 15 and 30. Arteriography was carried out at day 1. Light microscopy and scanning electron microscopy were performed on prosthesis sampled at day 15 and 30. Doppler flowmetry showed the full patency in all PTFE prosthesis. Angiography confirmed that all PTFE grafts were patent after 24 h. Doppler flowmetry, performed after 15 and 30 days, showed a reducing patency rate respectively at 70% (21 grafts) and 60% (18 grafts). Morphological studies showed that endothelial lining was not present at 15 day. After 30 days proliferation of blood cells occurred in the graft wall. Lumina presented a fibrous lining and did not show significant endothelial cell growths. These results confirm that PTFE prosthesis represents a suitable alternative to biological graft for the repair of small caliber artery when the latter are not available. Autologous vein is the vascular substitute of choice for peripheral vascular reconstruction, and PTFE prosthesis may be quite successfully used as a secondary choice, when multiple reconstruction are needed and biological grafts are not sufficient.

Angiography↗
PubMed2005

In vitro culture of mammalian early ovarian follicles. Morphofunctional correlates and future perspectives.

In vitro growth culture systems of mammalian oocytes have been developed with the aims of studying regulative processes occurring during oogenesis and folliculogenesis, and of preserving fertility. Although in large mammals IVG technology does not still assure the co-ordinate development of both somatic and germinal cells and the production of high number of viable offspring, their improvement may represent an important therapeutic tool for restoring fertility in women undergoing premature menopause or cancer treatments. Morphological studies of in vitro grown follicles were not performed extensively, especially by means of scanning electron microscopy. In the present paper preliminary ultrastructural observations of in vitro cultured follicles are presented.

Animals↗
PubMed2004

Mouse oocyte meiotic resumption and polar body extrusion in vitro are differentially influenced by FSH, epidermal growth factor and meiosis-activating sterol.

BACKGROUND: In this study, we compared the relative ability of FSH (100 mIU/ml), epidermal growth factor (EGF) (10 ng/ml), and follicular-fluid meiosis-activating sterol (FF-MAS, 10 micromol/l) to induce meiotic resumption and polar body I (PBI) extrusion in mouse oocytes. METHODS: Cumulus-enclosed oocytes (CEO) were co-incubated with meiosis-arresting agents, including 4 mmol/l hypoxanthine (Hx), 0.3 mmol/l dibutyryl cAMP (dbcAMP), and 8.5 micromol/l cilostamide, a selective inhibitor of the oocyte-specific phosphodiesterase 3 (PDE 3). RESULTS: In Hx-treated oocytes, FSH, EGF and FF-MAS induced meiosis resumption at very high rates, but only FSH and EGF also promoted PBI extrusion with high frequency. In experiments conducted in the presence of dbcAMP, FF-MAS was unable to promote an increase in germinal vesicle breakdown (GVBD) rate, whereas FSH and EGF generated a response similar to the Hx groups. Neither FSH, EGF nor FF-MAS caused any change in the meiotic status of CEO when meiotic arrest at the germinal vesicle (GV) stage was maintained by cilostamide. In the presence of Hx, naked oocytes (NkO) co-cultured with their cumulus cells were able to respond to the GVBD-inducing effect of FSH and EGF by resuming meiosis at high rate. CONCLUSIONS: Collectively, these results indicate that: (i) a signal triggered in cumulus cells by either FSH or EGF, but not necessarily coincident with FF-MAS, may contribute to meiotic maturation, supporting GVBD and extrusion of PBI; (ii) the transmission of this signal can occur in a paracrine fashion, at least with reference to the breakdown of the GV. It also appears that concomitant regulation of intra-oocyte cAMP degradation is a prerequisite for meiosis resumption.

Animals↗
PubMed2003

Capillary angiogenesis and degeneration in bovine ovarian antral follicles.

Angiogenesis and capillary degeneration are both evident during ovarian follicle growth. However, the characteristics and distribution of thecal capillary proliferative and degenerative structures have not been fully defined. Indeed, the role of thecal microvasculature changes in follicular atresia is still a matter of debate. The present study examined the distribution of thecal capillary changes occurring during follicular growth and related the changes to capillary morphology (by scanning electron microscopy, SEM, on bovine ovarian corrosion casts) with the incidence of capillary apoptosis (TdT-mediated dUTP nick end-labelling, TUNEL) and follicular status (as confirmed by follicular fluid steroid concentrations). SEM demonstrated well-perfused vascular plexuses of small to large antral follicles with structural and functional changes to capillaries. Angiogenesis was evident mainly in the apical part of the inner capillary layer of medium follicles and the middle or basal part of the inner capillary layer of dominant follicles that exhibited high oestradiol:progesterone ratios. Degenerative capillaries were observed mainly in the outer vascular layers of small follicles, and in the inner and outer vascular layers of medium antral follicles. Although apoptotic structures were present only in the outer capillaries of the theca interna of morphologically healthy antral follicles, atretic follicles showed apoptotic structures in both the outer and inner thecal capillary layers. These results show that angiogenesis increases during bovine follicular growth and occurs unevenly in different inner theca regions of the follicles. The differential angiogenic and degenerative response of theca interna capillaries may reflect differences in the microenvironment of the follicles, which in turn determine the fate of the follicles (continued growth versus atresia).

Animals↗
PubMed2002

Follicular microvasculature in the porcine ovary.

The microvasculature of porcine ovaries, with special regard to the follicles in the interstitial-stromal tissue, was studied by scanning electron microscopy (SEM) of vascular corrosion casts. Porcine ovaries displayed several coiled arteries in the hilus and many branches with small diameters and a tightly spiraling configuration in the cortical areas. However, small arterioles became straight before entering vascular complexes of follicles and finally divided into capillaries. Vascular baskets of various sizes (150-9,900 micro m in diameter) and architecture related to follicles in various developmental stages were observed in the ovarian cortex. Small follicles (150-300 micro m in diameter) began with a polygonal meshwork of a few large capillary meshes and developed to an obvious spherical microvascular network with a thin single layer of capillaries when reaching 500-700 micro m in diameter. The microvascular architecture of follicles 1,000-2,000 micro m in diameter developed further and had a three-layer vascular plexus. With a diameter of more than 2,000 micro m, the microvasculature of antral follicles was arranged as an inner vascular plexus of about 25 micro m, a middle plexus of about 100 micro m, and an outer capillary plexus of about 30 micro m in thickness. The present observations indicate that follicular vascular baskets of diverse sizes and architecture in various developmental stages support the gradual increase of follicular blood flow during follicle growth in the pig.

Animals↗
PubMed2002

A micro-anatomical model of the distribution of myocardial endomysial collagen.

Myocardial connective tissue probably provides passive support for regulating heart tensile strength and stiffness and ultimately for controlling heart mechanics through its endomysial part. However, endomysial collagen micro-arrangement is still a matter of debate. In order to define the fine distribution of left ventricle endomysial collagen, we applied the NaOH-scanning electron microscopy (SEM) maceration method (one of the techniques of choice for studying collagen micro-arrangement) to rabbit heart. Gomori-reticulum staining was used for correlated light microscopy (LM) observations. The SEM-NaOH method allowed isolation of collagen by removing other extracellular matrix components and cells and preserved collagen structure and position. Endomysial collagen appeared arranged in laminae that delimited the lacunae that were left empty by macerated myocytes and small vessels (mostly capillaries). These laminae were formed by reticular fibers, as confirmed by LM observations of Gomorireticulum-stained samples, and were organized in irregularly meshed networks made of thin (single) and thick (composed) filaments. In longitudinal views, collagen laminae extended the entire length of lacunae. In transversal views, the cut surface of the laminae appeared to be made of collagen bundles. These observations provide an updated microanatomical view of endomysial collagen distribution, which integrates previous studies. This model is based on the evidence that collagen laminae enveloped the surface of small vessels and myocytes. Thus, a type of myocyte-myocyte or capillary-myocyte "laminar connection" anchored to the entire cell length here is emphasized, rather than a type of "strut connection" anchored to defined loci, as usually described. This structure explains better how endomysium may provide the necessary support for heart compliance and protection against overstretch.

Animals↗
PubMed2001

In vitro fertilized human eggs. An electron microscopic study.

This paper describes by scanning and transmission electron microscopy the ultrastructure of the human fertilized egg and its vestments (cumulus oophorus and zona pellucida). Data are reported on the ultrastructure of a. conventional in vitro fertilized eggs (pronuclear eggs and cleaving eggs at two-to-four cell stage); b. eggs at the same developmental stage deriving fro intracytoplasmic sperm injection. The present results showed that: 1. The cumulus-enclosed fertilized egg is a highly dynamic structure in which egg vestments play a crucial role, positively affecting fertilization and healthy embryo development; 2. Intracytoplasmic sperm injection technique does not seem to significantly alter fertilized egg morphology.

Cell Nucleus↗
PubMed2000

Ultrastructure and distribution of interstitial glandular cells and associated elements in human fetal ovaries.

In order to understand the fine structure and distribution of the interstitial glandular cells (IGCs) and associated elements in the human fetal ovary, we studied human fetal ovaries at 16 weeks post fertilization (p. f.) by transmission electron microscopy. Semithin sections revealed voluminous typical IGCs usually grouped in clusters, located in the interstitium among the ovigerous cords. Isolated primordial follicles were seen in the cords located close to the interstitium in which IGCs were present. Besides the main ultrastructural characteristics of steroid secreting cells, the IGCs showed lipofuscin granules and stacks of annulate lamellae in their cytoplasm. Fibrocytes, macrophages and mast cells were detected close to the IGCs. In particular, the fibrocytes were located around the IGCs, with which they occasionally formed focal cell contacts. Fibrocytes issued numerous long projections, which, together with collagen fibers, surrounded the clusters of IGCs and small vessels (mainly capillaries), often extending into the intercellular spaces among IGCs. These data indicated that, already at the initiation of folliculogenesis, the IGCs are present numerously in a close association with the ovigerous cords. The morphological aspects of IGCs were comparable to that of fetal testis interstitial (Leydig) cells and hilar cells in adult ovary, and suggest that fetal IGCs may be source of adult ovary hilar cells. In addition, we have here demonstrated for the first time that IGCs are associated with stromal cells whose distribution seems to support IGCs microtopography. Fetal ovarian fibrocytes revealed a structural arrangement similar to that of the "compartmentalizing cells" previously described in the adult testis. Macrophages and mast cells presumably have a role as local modulators of steroid synthesis. Mast cells may also affect fibrocyte organization and vascular permeability. We thus suggest that IGCs and associated cells may form a glandular unit in the human fetal ovary similar to that in the adult testis, and this structure is likely involved in early steroid secretion during gonadal differentiation.

Female↗
PubMed1999

An unusual peritoneal fossa: anatomic report and clinical implications.

The peritoneal fossae are usually related to rotation and adhesion of the abdominal viscera to the posterior abdominal wall during fetal development, and/or the presence of retroperitoneal vessels running just under the peritoneum and raising serosal folds. These fossae, therefore, are regarded as congenital and have been considered clinically and surgically as sites of internal abdominal hernias. The authors describe a peritoneal fossa interposed between the fourth portion of the duodenum and the abdominal aorta. Due to a scoliosis of the lumbar column, the abdominal aorta had shifted to the left of the duodenum, stretching two semilunar avascular peritoneal folds connecting the vessel with the ascending duodenum. These two folds bounded above and below an entrance into a fossa lined by the posterior parietal peritoneum and bordered by the fourth portion of the duodenum on the right and the aorta on the left. This recess extended as far as the anterior surface of the second and third lumbar vertebrae. On the basis of the anatomic findings, the authors suggest that acquired fossae, because of their size and topography, may play a part in the etiopathogenesis of internal abdominal hernias.

Aged↗
PubMed1998

Ultrastructural features of bovine cumulus-corona cells surrounding oocytes, zygotes and early embryos.

Integrated transmission and scanning electron microscopic (TEM and SEM) techniques have provided the first detailed description of the ultrastructural features of the bovine cumulus-corona (CC) cells surrounding oocytes at the time of final maturation, zygotes and early cleaving embryos (2/4 to 6/8 blastomeres). TEM revealed the presence of rough endoplasmic reticulum and Golgi complexes in the cytoplasm of CC cells surrounding immature, mature and fertilized eggs, and also revealed an increasing amount of smooth endoplasmic reticulation membranes, lipid droplets and mitochondria with villiform and/or tubular cristae in the cytoplasm of CC cells during maturation and fertilization of the oocyte. In addition, a loss of cell-to-cell junctions between CC cells was evident. TEM also demonstrated that a few residual CC cells were still associated with early embryos and that these cells showed rather degenerative or apoptotic patterns, the latter pattern also observed on cells associated with fertilized eggs. SEM revealed that the complex of CC cells of immature oocytes was compact with narrow intercellular spaces, which progressively enlarged in size around mature oocytes. This phenomenon is mostly due to the production of abundant extracellular matrix. Immature CC cell complexes possessed characteristic long and filiform microvilli whereas the surface of CC cells surrounding mature oocytes showed numerous blebs and occasional large cytoplasmic protrusions as well as microvilli. Zygotes and early embryos were covered with a few polyhedral CC cells possessing scarce and short microvilli and a large amount of pleomorphic blebs. This study demonstrated a precocious luteinization occurring in bovine CC cells at ovulation until zygote segmentation, and this process was associated with a progressive apoptotic mechanism that ended in the complete denudation of the zona pellucida covering the early embryo. The presence of CC cells around the maturing oocyte and fertilized egg could have important functions related to the microenvironmental requirements of ovum maturation as well as facilitating activities related to fertilization.

Animals↗
PubMed1998

Functional and ultrastructural evidence of myocardial stunning after acute carbon monoxide poisoning.

OBJECTIVE: To study human myocardial ultrastructural changes after carbon monoxide (CO) poisoning inducing reversible cardiac failure. DESIGN CASE REPORT: clinical, functional and morphologic findings. SETTINGS: Public university-affiliated hospital and electron microscopy laboratory. PATIENT: A 25-yr-old woman with functional evidence of cardiac failure after acute CO poisoning. INTERVENTIONS: Hyperbaric and intensive care treatment over 10 days. Scintigraphic and cardiac angiography with endomyocardial biopsy. MEASUREMENTS AND MAIN RESULTS: Scintigraphy with 99mTc hexakis 2-methoxy-2-isobutyl isonitrile (sestaMIBI) showed an uptake defect in the left anterior descending artery territory. The cardiac angiography demonstrated a slight hypokinesis of the superior two thirds of the anterior wall and of the septal region with completely normal coronary angiograms. Electron microscopy of left ventricular biopsies showed slight ultrastructural changes in the myocytes. In addition, large glycogen deposits were mostly associated with swollen mitochondria. The patient was discharged in good clinical condition on day 10. CONCLUSIONS: Presence of glycogen deposits associated with abnormal mitochondria may be signs of the incapability of myocardial cells in utilizing energy substrata. In the presence of normal myocardial perfusion, our findings are consistent with the presence of a stunned myocardium-like syndrome. Early recognition and treatment of this clinical syndrome allow the prevention of myocardial infarction.

Adult↗
PubMed1998

The microvasculature of the corpus luteum in pregnant rabbit. A scanning electron microscopy study of corrosion casts.

The vascular network of pregnant rabbit ovaries was studied by means of scanning electron microscopy (SEM) of corrosion casts, in order to evaluate the morphofunctional changes of the microcirculation of corpus luteum (CL). Pregnant rabbit ovary showed an overwhelming vascularization. Ovarian hilus displayed an increase in the arterial spirallisation. The arterial spiral pattern was present along the entire vessel course, up to CL tissues. The CL of pregnancy was supplied by wide vascular plexuses (2-5 plexuses were found in each pregnant ovary) whose major axis was about 2 mm. Luteal capillaries showed a tortuous course and were arranged in a three-dimensional, wide and rounded-meshed network. Postcapillary venoconstrictions were present. The venous drainage appeared more developed then the arterial supply. Tight artero-venous contacts in hilar, juxtamedullar and medullar regions of the ovary were observed. These results clearly show that the morphofunctional expression of CL of pregnancy is greatly dependent on its hemodynamic control. In particular, the increase of spirallisation exhibited by the arteries during pregnancy is likely to be considered a significant functional change. The spirallisation likely is a device for reducing the blood pressure through the CL. The artero-venous contacts, also previously described in hCG stimulated (pseudopregnant) ovaries, may support a counter-current like system that may allow a veno-arterial exchange of small molecules through the wall of the facing vessels. In addition, in 10-day pregnant rabbit CL the consolidation of a well-developed capillary network was revealed, which is a sign that the CL of pregnancy reached the full morphofunctional maturation. Furthermore, the CL of 10-day pregnant rabbit did not present significant capillary permeabilization and dilation or angiogenic processes, aspects that were previously found in stimulated periovulatory ovaries. Indeed, changes of the arterial supply and venous drainage of the CL of pregnancy were demonstrated. This suggests that the control of the blood flow through the CL of pregnancy may be transferred from the local capillary microcirculation to the regional artero/venous circulation. This may be probably related to the significant increase of the ovarian blood flow necessary for the maintenance of CL endocrine functions during pregnancy.

Animals↗
PubMed1998

Egg-sperm interactions in humans: ultrastructural aspects.

A large cumulus mass usually covers the human ovulated oocyte, and voluminous clusters of cumulus cells are still seen after fertilization around the egg. Cumulus cells surround oocytes and fertilized eggs also during in vitro fertilization (IVF) procedures. This study describes, by transmission and scanning electron microscopy, the morphology and the microtopography of the cells forming the human cumulus mass surrounding IVF samples (insemined but not fertilized oocytes and fertilized eggs). Particularly emphasized is their morphodynamic role in sperm-egg interactions. A comparison with the behavior in vivo of cumulus-enclosed oocyte/fertilized eggs has been also performed. All patients have given their informed consent to participate in this protocol. An inner layer (corona radiata cells) and an outer layer (proper cumulus cells) can be microtopographically recognized in the cumulus mass. Numerous cumulus-corona cells, particularly after fertilization, showed ultrastructural characteristics typical for steroid synthetic cells, thus undergoing a sort of "luteinization" parallel to that occurring in the sister granulosa cells of the postovulatory follicle. This steroid synthetic activity, particularly enhanced in vitro but present also in vivo, may be finalized to the release of small amount of steroids (estrogens and progesterone) in the oocyte/fertilized egg milieu. Various proteins, secreted by other cell subpopulations--as revealed in other studies by our research group--, may even enrich this milieu. Lymphocytes and macrophages were often found in the cumulus mass. They may modulate the steroid secretion of the neighboring cumulus cells by production of cytokines, mimicking what occurs in the ovarian follicle and, later, in the corpus luteum. Spermatozoa, both normal (acrosome-intact or--reacted) and abnormal, were frequently seen in the cumulus mass, free in the intercellular spaces or close to the cumulus cells, that can induce sperm capacitation and acrosome reaction. Leukocytes and cumuluscorona cells appeared both capable of actively phagocytizing supernumerary and/or abnormal sperms. Such spermiophagic response is present in a lesser extent around oocytes and eggs fertilized in vivo. In vitro, instead, cumulus spermiophagy leads to the elimination of a large part of the excess spermatozoa that have reached the oocyte, thus restoring in an extracorporeal medium the spermiophagic activity physiologically exerted by leukocytes and epithelial cells in the female and male genital tracts. In conclusion, the cumulus mass surrounding oocytes and fertilized eggs appears as a highly dynamic system, in which various subpopulations of cells cooperate in order to provide a suitable and healthy microenvironment for fertilization and early embryo development.

Blastomeres↗
PubMed1997

The angioarchitecture of estrous, pseudopregnant and pregnant rabbit ovary as seen by scanning electron microscopy of vascular corrosion casts.

Ovarian angioarchitecture was studied by scanning electron microscopy of vascular corrosion casts in estrous, pseudopregnant (stimulated with human chorionic gonadotropin) and pregnant rabbits. In all samples, the proper ovarian branch of the ovarian artery (ramus ovaricus) entered the ovarian hilus near the caudal pole of the organ and ran parallel to the major axis of the hilus. The extraovarian venous drainage was formed by several vessels emptying into a distal large vein. The ramus ovaricus exhibited various degrees of coiling and branched in the medulla. The coiling of the ramus ovaricus and its ramifications were maintained in all samples. A venous meshwork and/or flat vein branches closely enveloped the arterial coils found in the hilus and outer medulla. At this level numerous arteriovenous contacts were demonstrated in all samples. The coiled arteries, prior to entering the ovarian cortex, supplied several small peripheral follicles which were drained by the hilar veins. In the cortex the coiled arteries branched in numerous thin, straight or slightly undulated arterioles which supplied developing estrous follicles and pseudopregnant corpora lutea. The arterioles supplying the pregnant corpora lutea were long, large and tightly spiraled. The venous drainage followed the modifications of the arterial supply. These data demonstrate that ovarian cycle and pregnancy induced significant changes in the cortical vessels, which adapted their structure to the temporary functional needs of the recruited follicles or corpora lutea. Hilar and medullary vessels have permanent structures that may represent morphological devices for (a) a continuous control of the blood flow (spiral arteries) and (b) a local recirculation of endocrine products (arteriovenous contacts) comparable to the "countercurrent mechanism" previously shown to operate in ovaries of other species, but not yet found in rabbits.

Animals↗