Biomedical subjects

S A Nottola

Publications and source records attributed to S A Nottola.

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↗

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

Ultrastructural dynamic features of in vitro fertilization in humans.

The present study on in vitro fertilization in humans demonstrates that three-dimensional (3-D) fine morphology by high resolution scanning electron microscopy (SEM) combined with parallel light and transmission electron microscopy (TEM) can reveal a number of new cellular detailed findings which cannot be detected with other methods. In this study the following aspects have been investigated in early human embryos. 1. Micro-topographical features of the zona pellucida (ZP), surface blastomeres and polar body. 2. Intracytoplasmic features of mature and healthy oocyte, in vitro fertilized (IVF) oocyte and early embryo development. 3. Comparison of general views of intracytoplasmic sperm injection (ICSI) and conventional IVF (C-IVF) of early embryos. 4. Presence of unusual large tubular smooth endoplasmic reticulum (SER) aggregates in 4, 5, and 6-cell embryos after ICSI. 5. Inside views of 3-D blastocysts such as inner cell mass and trophoblast. To our knowledge, this is the first time that such images are reported by using these techniques.

Blastocyst↗

PubMed2001

The human zona pellucida and scanning electron microscopy. Reality or artifacts?

The surface micro-morphology of the zona pellucida (ZP) was investigated in 158 inseminated but unfertilized mature human oocytes derived from assisted reproduction trials (ART) by means of traditional scanning electron microscopy (SEM) techniques (gold coating and conductive staining methods) and saponin-ruthenium red-osmium tetroxide-thiocarbohydrazide method (Sap-RR-Os-TC). The main aspect of the ZP by traditional SEM (122 oocytes) consisted in a porous, net-like structure (97 oocytes), whereas a nearly smooth or compact structure of ZP was detected in 25 oocytes (79.5% vs 20.5%). Using Sap RR-Os-TC method on 36 oocytes, 31 oocytes showed ZP with alternating tight and large meshed networks, whereas 5 oocytes displayed only tight meshed network (86.1% vs 13.9%). Due to our well standardized procedures, to the stabilizing action of the conductive staining on the zona material and similar results obtained with the use of Sap RR-Os-TC method, we confidentially regard the ZP changes, occurring in oocytes of various groups, as genuine features, likely related to their actual maturation status, rather than as artifacts. In addition, we emphasize the concept that a modern view of the ZP surface implies the best evidence of crossing filaments' network. We think that the ZP "spongy" or "compact" appearance is only the result of microfilaments network collapse, not the true three-dimensional (3-D) representation of ZP structure.

Artifacts↗

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

Human embryo development and pregnancies in an homologous granulosa cell coculture system.

PURPOSE: Our purpose was to determine the effects of the coculture of embryos on human granulosa cells (GCs) in patients in the first cycle of IVF-ET treatment and in patients with repeated implantation failures and to investigate the presence of specific proteins in a 48-hr GC conditioned medium and the GC ultrastructural characteristics. METHODS: Eighteen patients with tubal or idiopathic infertility were enrolled in this study: 7 patients (Trial 1) were in the first cycle of IVF-ET treatment and 11 patients (Trial 2) had repeated implantation failures (one to five). Embryos from each patient were cocultured randomly either on homologous granulosa cells or on a conventional culture medium. RESULTS: At the end of the coculture period (day 5 or 6), 50% of the embryos (Trial 1) reached the blastocyst stage, with respect to 35% in Trial 2. The pregnancy rate per retrieval was 14.2 and 9%, respectively, in Trial 1 and in Trial 2. Many conditioned media showed proteins of 24-29 kDa. and some of them showed additional proteins of 90 kDa. The ultrastructural analysis of GCs showed healthy, metabolically active, protein-synthesizing, and mostly steroidogenic cells. CONCLUSIONS: GC cultures improve embryo development but not pregnancy rates both in Trial 1 and in Trial 2.

Adult↗

PubMed2000

Mitochondrial morphology in human fetal and adult female germ cells.

The aim of this study has been to observe, by electron microscopy, the morphological changes affecting mitochondria and associated organelles in the human female germ cell during oogenesis, maturation and fertilization. In the primordial germ cell (PGC), rounded mitochondria with a pale matrix and small vesicular cristae are disposed near the nucleus and significantly increase in number during PGC migration and settlement in the gonadal ridge, where they differentiate into oogonia. In these early stages of mammalian oogenesis, aggregates of mitochondria are typically clustered around or in close relationship with the nuage. In oocytes at early prophase stage, mitochondria proliferate while aligned along the outer surface of the nuclear membrane, contain a more dense matrix than before, and have lamellar cristae. Oocytes of primordial and primary follicles mostly contain round or irregular mitochondria whose matrix has become very light. These mitochondria show typical parallel, arched cristae, and are clustered near the nucleus with other organelles forming the Balbiani's vitelline body. When follicles grow, the mitochondria of the oocytes become even more numerous and are dispersed in the ooplasm. Both paranuclear accumulation and subsequent dispersion of mitochondria in the cytoplasm are likely to be regulated by microtubules. By ovulation, mitochondria are the most prominent organelles in the ooplasm. They form voluminous aggregates with smooth endoplasmic reticulum (SER) tubules and vesicles. These mitochondrial-SER aggregates (M-SER) and the mitochondrial-vesicle complexes (MV) could be involved in the production of a reservoir of substances or membranes anticipating subsequent fertilization and early embryogenesis. Just after fertilization, the mitochondria of the oocyte undergo a further substantial change in size, shape, and microtopography. In the pronuclear zygote, mitochondria concentrate around the pronuclei. During the first embryonic cleavage divisions, round or oval mitochondria with a dense matrix and few arched cristae are gradually replaced by elongated ones with a less dense matrix and numerous transverse cristae. A progressive reduction in size and number of M-SER aggregates and MV complexes also occurs. In summary, oocyte mitochondria show dynamic morphological changes as they increase in number and populate different cell domains within the oocyte. They form complex relationships with other cell organelles, according to the different energetic -metabolic needs of the cell during differentiation, maturation, and fertilization, and are ultimately inherited by the developing embryo, where they eventually assume a more typical somatic cell form.

Adult↗

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↗

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

Bovine cumulus-corona cells in maturing oocytes. A scanning electron microscopic study.

The ultrastructural features of cumulus-corona cells surrounding maturing oocytes in bovine were studied by means of scanning electron microscope in order to provide a detailed description of their surface changes during oocyte maturation. Cumulus corona cell complexes of immature oocytes showed a compact aspect with narrow intercellular spaces. The spaces around mature oocytes enlarged because they were progressively filled with abundant microfibrillar extracellular matrix. In cumulus corona cells complexes of immature oocytes very numerous long and filiform microvilli were observed, whereas the cumulus corona cell surface surrounding mature oocytes showed occasional large cytoplasmic protrusions along with scanty microvilli and numerous blebs.

Animals↗

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↗

PubMed1997

Natural history of the female germ cell from its origin to full maturation through prenatal ovarian development.

This paper contains a number of sketches concerning the main morphological ultrastructural features of the human female germ cell during the prenatal period. The morphodynamic outline of primordial germ cells has been traced, both in their extraembryonic site of origin and during their migration towards the developing ovary. After gonadal settlement, the intraovarian differentiation of the germ cells into primary oocytes through the stage of oogonia, as well as the dramatic fall in the number of germ cells before birth, is described. The presence of morphofunctionally relevant interactions between the differentiating female gamete and the surrounding somatic microenvironment has also been evaluated and discussed.

Cell Count↗

PubMed1996

Heterogeneous distribution of fibronectin, tenascin-C, and laminin immunoreactive material in the cumulus-corona cells surrounding mature human oocytes from IVF-ET protocols--evidence that they are composed of different subpopulations: an immunohistochemical study using scanning confocal laser and fluorescence microscopy.

Monoclonal antibodies and immunofluorescence microscopy, including laser confocal microscopy, were used in this study to point out the production of fibronectin, tenascin-c, and laminin in the cumulus-corona (CC) cells surrounding mature human oocytes from IVF-ET protocols in view of their presumptive importance in the coordination of the processes leading to fertilization and early embryo cleavage, including the final maturation of the ovum, the sperm-egg interaction, and the "complex biochemical dialogue" between the gamete and the oviduct through the tubal luminal environment. One hundred fifty mature oocyte-CC complexes were obtained from IVF-ET protocols and fixed in 4.0% buffered paraformaldehyde. Specimens were incubated with a panel of primary monoclonal antibodies (mabs) recognizing different epitopes of fibronectin, tenascin-c, and laminin and then with fluorescein isothiocyanate-conjugated goat anti-mouse IgG. Observations were made by a scanning confocal microscope (Sarastro 2000) and a photomicroscope (Polyvar, Reichert-Jung) equipped with epifluorescence optics. The immunohistochemical data demonstrated that human CC cells are capable of producing fibronectin and tenascin-c but that their production is not homogeneous in the CC population. In fact, fibronectin immunoreactivity was shown mostly by inner CC cells (mainly corona cells), whereas tenascin was produced by some cells scattered in the entire cumulus mass. Moreover, fibronectin and tenascin-c immunoreactive material was observed in the intracytoplasmic areas, at the plasma membrane level as well as in the extracellular matrix. On the contrary, laminin immunofluorescent material was found around plasma membranes of almost all CC cells, but a clear intracytoplasmic reaction was never observed. This leads us to assume that laminin in the extracellular matrix remains entrapped once produced by granulosa follicular cells and that in the postovulatory period no active secretion occurs in CC cells. Even though the functional role of these extracellular matrix proteins remains still unclear, it is reasonable to suggest that they are necessary in various steps of the reproductive process, i.e., from the pick-up of the oocyte, its transport through the oviduct, and fertilization, up until the early cleavage of the embryo. Finally, functional differences between "corona radiata" and "cumulus" cells during the oocyte denudation may be accounted for particular distribution of these adhesive proteins.

Fertilization in Vitro↗

PubMed1995

Ultrastructure of human cumulus oophorus: a transmission electron microscopic study on oviductal oocytes and fertilized eggs.

The aim of the present study was to assess the heterogeneity of cumulus cells that occurs in human cumuli associated with oviductal oocytes and fertilized eggs. Transmission electron microscopy was used to study the cumulus masses surrounding both unfertilized oocytes and fertilized eggs (a pronuclear and a 4-cell stage) recovered at different intervals after ovulation. The specimens were obtained by flushing the oviducts of normal cycling women who underwent surgical sterilization. The cumuli were expanded due to large and irregular intercellular spaces; small linear gap junctions were seen at cell contacts, whereas annular gap junctions were found only in the cytoplasm of some cells. Both types of junction were less abundant in fertilized specimens. Cells surrounding fertilized eggs projected numerous long, thin microvilli into the intercellular spaces. As a rule, the inner layer of the cumulus mass (corona cells) was composed of cells whose surface was relatively smooth. Cumulus cells showed oval nuclei with one or more nucleoli. The cytoplasm of most cells possessed abundant organelles typical of steroidosynthesis: (i) mitochondria with tubular or villiform cristae; (ii) a well-developed smooth endoplasmic reticulum; and (iii) electron dense lipid droplets often surrounded by a few concentric membranes of smooth endoplasmic reticulum and/or in close contact with microtubules and microfilaments. Microperoxisome-like structures were also present. After fertilization, an enhancement of the steroidosynthetic characteristics occurred in the outer layers of the cumulus mass, but not in the corona cells, which still appeared capable of protidosynthesis. Together, these morphological features support the hypothesis that the cumulus of oviductal oocytes and particularly of fertilized eggs, luteinizes like parietal granulosa cells, generating a steroid hormonal micro-environment in the oviduct which may affect fertilization and zygote segmentation. Cumulus cells showing spermiophagic activity, as well as activated macrophages, leukocytes and red blood cells, were also found in the cumulus mass. The macrophages may play a local role both by phagocytic activity and by modulating the steroid secretion of the neighbouring cumulus cells which occurs in the ovarian follicle and corpus luteum. In conclusion, the cumulus mass surrounding tubal oocytes and fertilized eggs appears to be a heterogeneous and dynamic system, in which the micro-environment for fertilization and early embryo development is provided by diverse cell populations in addition to the oviductal cells.

Adult↗

PubMed1995

Changes of ovarian microvasculature in hCG stimulated rabbits. A scanning electron microscopic study of corrosion casts.

The microvasculature of the ovarian cortex was studied by means of scanning electron microscopy of vascular corrosion casts in estrous and hCG stimulated rabbits in order to establish a better understanding of the structural as well as functional vascular changes which accompany the evolution of the luteofollicular complex. According to the various shape and size seven different morphological types of vascular plexuses corresponding respectively to antral follicles (Types 1-2), atretic follicles (Types 3-4), periovulatory follicles (Type 5), growing pseudopregnant corpora lutea (Type 6) and regressing pseudopregnant corpora lutea (Type 7) were identified. Growing to mature cycling type follicles (Types 1-2) showed a gradual enlargement and proliferation of the theca capillaries. These changes, associated with capillary hyper-permeabilization were observed in ovulatory and post-ovulatory follicles (Types 5), after hCG stimulation. The corpus luteum formation (Types 6) was accompanied by additional capillary dilatation, diffuse angiogenetic sprouts and organization of a more conspicuous venous drainage. The regression of the corpus luteum (Type 7) was characterized by the appearance of avascular areas within the glandular tissue and by regression of vascular dilatation. The atretic follicle (Types 3-4) wall showed large interruptions (avascular areas) and focal invasion of the central cavity by newly formed capillaries randomly arranged. The hCG stimulation did not affect consistently the atretic follicle microvasculature. The present observation shows that both thecal capillary vasodilatation and angiogenetic processes support the gradual increase of ovarian blood flow during follicle growth and corpora lutea formation and that microvascular changes of atretic follicles are possibly related to a type of inflammatory reaction since they seem to be a consequence rather than a primary cause of atresia.

Animals↗

PubMed1993

Ultrastructure of human ovarian primordial follicles after combination chemotherapy for Hodgkin's disease.

Ovarian damage, with consequent permanent infertility, is one of the more common side-effects which occurs during chemotherapeutic treatment of patients affected by Hodgkin's disease. This damage is morphologically represented by a marked loss of primordial and primary follicles. The administration of contraceptive drugs before starting chemotherapy enhances survival of a greater number of ovarian follicles, as revealed by morphometric analyses, nevertheless, total ovarian protection is not assured. This study evaluated the number and the morphology of ovarian follicles, by means of transmission electron microscopy, in patients with Hodgkin's disease treated with multi-drug chemotherapeutic protocols following the administration of medroxyprogesterone acetate. Ovarian biopsies were performed prior to any pharmacological treatment, after medroxyprogesterone therapy, and after this therapy plus chemotherapy. Particular attention was given to the ultrastructure of primordial follicles. After morphometric evaluation, primordial follicles were numerous in controls and medroxyprogesterone therapy (28.55 +/- 6.59/mm3 of ovarian cortex). After chemotherapy and medroxyprogesterone acetate, the number of follicles was slightly reduced (19.37 +/- 3.41/mm3 of ovarian cortex) in contrast to the dramatic loss usually observed when protection is not given, although more follicles were atretic. Medroxyprogesterone may protect follicles only from acute, toxic effects of chemotherapy, which dramatically reduce their number and lead to sterility. Nevertheless, the quality of follicles is still impaired, and many undergo atresia, resulting in a shortened fertility period.

Adult↗