Biomedical subjects

S Makabe

Publications and source records attributed to S Makabe.

At least 19 recordsLinked to original sources

PubMed2006

Microplicae-like structures of the fallopian tube in postmenopausal women as shown by electron microscopy.

Female reproductive aging is associated with several morphological changes of the genital tract with a subsequent decline in fertility; however, ultrastructural changes occurring after menopause have still not been well illustrated. Our aim was to characterize the three-dimensional microanatomy of the luminal surface of the human fallopian tube in perimenopause and postmenopause. Twenty bioptic samples of fallopian tubes were obtained after surgery under the informed consent of the patients. Samples were processed for transmission electron microscopy (TEM) and field-emission scanning electron microscopy (FE-SEM). As age increases the surface epithelium of the fallopian tube appeared somewhat flattened. Correlated TEM/FE-SEM observations showed gradual shortening of microvilli and deciliation. The most interesting finding was the gradual formation of microplicae-like structures on the surface epithelium, particularly from late perimenopause to postmenopause. Microplicae-like structures, associated with other regressive changes, represent an important adaptation of the epithelium of the fallopian tube; these are likely induced by the physiological process of aging, thus better withstanding hormonal changes associated with the advent of the menopause.

Aged↗

PubMed2005

Microscopical survey of the development and differentiation of the epithelium of the uterine tube and uterus in the human fetus.

The development and differentiation of the coelomic epithelium lining the paramesonephric ducts in human fetus, that gives rise to the female genital organs, have been ultrastructurally examined. The epithelium appeared pseudostratified, consisting of basal, microvillous and ciliated cells. In younger fetuses (12th gestational week) ciliogenic elements could be detected mainly on the developing tubal fimbriae, but most of the cells showed microvilli and often single cilia. In the subsequent phases of development, morphodynamics of cell renewal were documented by aspects of apoptosis. Fully ciliated cells were numerous on the fimbriae and at the utero-tubal junction, but not in the uterus; however, these were less abundant than those showing microvillous. In older fetuses (31st gestational week) microapocrine secretion by microvillous cells, in the form of droplets contacting cilia, could be observed. In the same fetuses the ectocervix was covered by a mature squamous epithelium, made up of polygonal flat desquamating cells, showing labyrinthine surface microplicae. Our observations demonstrated that ciliation in the human female genital organs, like that of other systems, is neither simultaneous nor uniform, and ciliated cells are gathered preferentially in strategic sites, to mediate germ cell migration and blastocyst implantation in adult life. These ultrastructural data seem to indicate that the female genital tract epithelium, at least in its general features, is sketched since fetal life, and cell morphodynamics, including microvillous and ciliated cell differentiation, as well as the secretory activity, are the morphological expression of the complex molecular mechanisms, involved in developmental biology and reproductive physiology.

Aborted Fetus↗

PubMed2005

Pietro Motta's latest studies on the microanatomy of menopause: revised concepts on the beauty of aging.

Menopause signs a hallmark in women's life. When compared to traditional two-dimensional techniques, scanning electron microscopy (SEM) allows to discover the impressive microcosm of the human body and offers original views of the real three-dimensional ultrastructure of reproduction. On the basis of Prof. Motta's last and original book, herein we show a selection of microscopic images that characterize the 3D changes taking place on the surface epithelia of the aging woman's reproductive tract. Biopsies of ovaries, tubes, uteruses, cervices and vaginas were obtained from women (45-72 years old) during surgical or endoscopical procedures and after the informed consent of the patients. Samples were processed for SEM as reported elsewhere. Reproductive aging is associated to epithelial flatness, higher stromal density, absence of ovarian follicles, thickening of vascular walls and lack of glandular secretion. The uterus and the tube show a morphodynamic sequence of gradual microvilli shortening, patchy to complete deciliation and formation of microplicae like structures. The formation of microplicae like structures is interpreted as an adaptive mechanical response of the genital epithelia to the new microenvironment. We can propose that these structures may represent the initial stage of a physiologic metaplasia. In conclusion, imaging of menopause through the use of SEM allows a better understanding of the morphological and physiopathological bases of female aging and represents a perfect blend of art and aesthetics: a further confirmation of the endless beauty of our inner microscopic anatomy.

Aged↗

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

Ultrastructural morphodynamics of human Sertoli cells during testicular differentiation.

Our study reviews and ultrastructurally characterises human pre-Sertoli cells between the 6th and the 20th week of gestation by means of integrated light microscopy, transmission electron microscopy and high resolution scanning electron microscopy (standard or following ODO maceration). The morphofunctional differentiation of Sertoli cells defines testicular differentiation. These somatic cells are mostly of mesonephric origin and can be first morphologically recognised in 7 week-old embryos altogether with the formation of testicular cords. The latter organise as primordial germ cells surrounded by pre-Sertoli cells. Due to the great synthetic activity of pre-Sertoli cells the rough endoplasmic reticulum develops. The basal lamina of the cords becomes distinguishable at 7 to 8 weeks of gestation. Both prespermatogonia and pre-Sertoli cells actively proliferate but the latter greatly outnumber prespermatogonia. Many interdigitations and cytoplasmic processes are observed between neighbouring pre-Sertoli cells. Due to cell proliferation a sort of compartmentalisation is established inside the cords in which pre-Sertoli cells tend to localise closer to the basal membrane embracing prespermatogonia with long and thin cytoplasmic processes. One of the main typical features of differentiating pre-Sertoli cells is the irregular nucleus and the prominent nucleolus. When the embryo is 14 to 20 weeks-old pre-Sertoli cells maintain their general morphology whereas the most significant change is the maximum development of Leydig cells. Testicular cords do not show any lumen at all so they cannot be termed "tubules".

Cell Differentiation↗

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

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

Aging and oxidative stress in neurodegeneration.

The effect of oxidative stress on the function of brain synapse, the difference in susceptibility of synapse to hyperoxia with age, and the changes in vitamin E status by stress and aging were investigated. Synaptic membrane permeability to sucrose was increased with age. When rats were subjected to hyperoxia, the membrane permeability on each age increased significantly. The susceptibility of synapse of 25 month old rats exposed to stress was about 2.5 times higher than unexposed old rats. The synaptic plasma membrane fluidity decreased significantly either in response to hyperoxia or during aging. The thiobarbituric acid reactive substances (TBARS) in the synaptic plasma membranes increased with age, and those in the membranes of oxygen-exposed rats were higher than in the unexposed rats. The cholesterol/phospholipids (C/P) ratio of the membranes increased significantly with age, and the values in the membranes of oxygen-exposed rats increased more significantly than in unexposed rats of each age. In a measurement of fatty acid content in the membranes, the content of docosahexaenoic acid (DHA, C22:6) decreased significantly during aging and by hyperoxia. These results suggest that free radicals derived from oxygen may attack nerve terminals and peroxidize the membrane, resulting in the deterioration of function of brain synapse, and that susceptibility of synapse to oxidative stress was significantly increased with age. Vitamin E content in the synaptic plasma membranes decreased with age. When rats were subjected to oxidative stress, the content was lower in each age than in normal rat membranes. An intraperitoneal administration of vitamin E prior to stress reduced these abnormalities. It is obvious that vitamin E contributes to the protection against nerve terminal dysfunction caused by oxidative stress.

Aging↗

PubMed1998

A three-dimensional study of human fetal endocervix with special reference to its epithelium.

The development of human fetal cervix has been systematically studied by SEM, obtaining a detailed map of its fine structure, particularly concerning the differentiation and maturation of the endocervical epithelium, including its "eversion" and "squamous metaplasia", normally occurring in postnatal life, but not yet observed in detail by electron microscopy in the fetus. Cervices from spontaneous abortion at 12, 15, 18, 20, 21 and 22 weeks and from intrauterine fetal death (hydrocephalus) at 31 weeks of development have been examined. At 12-15 weeks, as the canalization of the cervix proceeded, the endocervical epithelium consisted of high polyhedral cells, with regularly flattened or concave apices exhibiting scarce microvilli and often single primary cilia. Some narrow intercellular infoldings probably corresponded to primordial tubular glands. At the 18th week the epithelium was made up of a mosaic of flat or slightly raised polygonal cells, whose apical surface showed thin microplicae. At the 20th week a pseudostratified epithelium with many apically convex cells lined the cervical canal and the tubular glands. At 21 and 22 weeks "plicae palmatae" developed, covered by cells, often showing a smooth central area surrounded by microvilli, provided with a primary cilium and swollen by secretory material. This also formed rounded masses on the epithelium. In the lower part of the endocervix some very elongated cells showed short microplicae resulting from fusion of microvilli. At the 31st week secretion increased and its products spreading from the bottom of the glands contacted isolated ciliated cells at their openings and diffusely covered the surface epithelium. Most of the ectocervix exhibited squamous elements, with well-developed labyrinthine microplicae. These cells could overlap each other and also desquamate. The zone of the portio vaginalis around the os of the cervical canal appeared infolded and hypertrophic. Here, an indented squamo-columnar junction between the ectocervical and endocervical epithelium, caused by tongue-like prolongations of squamous epithelium directed toward the endocervix, was found. Their tips consisted of elongated cells, rich only in short microvilli. Our data indicate that the features of the microvillous cells are an expression of a hormone-dependent differentiative process. Thus, their secretion might be stimulated by progesterone. Similarly microplicae on the ectocervical epithelium (a sign of squamous maturation) might be promoted by estrogens. Furthermore, two aspects were significative: 1) the finding--in an early phase only (18th week)--of endocervically-located squamous cells, although devoid of microplicae; and 2) the occurrence--in the latest phase (31st week)--of an indented squamo-columnar junction on the surface of the portio. These features are in agreement with the caudal shift of the squamo-columnar junction near the uterine cavity to the ectocervix after cervico-vaginal demarcation; the squamous metaplasia of this everted endocervical epithelium has been reported by some authors. It is likely that these processes, occurring in fetal life as well as in pregnant women, are related to a common hormonal background, arising from the mother to her fetus.

Cervix Uteri↗

PubMed1998

Microanatomy of the female reproductive organs in postmenopause by scanning electron microscopy.

The detailed three-dimensional ultrastructural features of the reproductive organs of menopausal and postmenopausal women were studied by means of integrated transmission and scanning electron microscopy (SEM) and reported in a new colored microtopographical fashion. These methods revealed significant alterations in the microanatomy of the various reproductive organs specifically related to the decline of plasma estrogen levels. In particular, the ovary progressively showed characteristic wide areas of loss of epithelium with consequent exposure of the underlying connective tissue. Both endometrial and tubal mucosa demonstrated a gradual but often dramatic decrease in the number of ciliated cells which was more evident in the tube. In addition, the non-ciliated (microvillous secretory) cells of the uterus, including both endocervix and tubal mucosa, became flattened and, in some instances, their apical poles developed unusual wrinkles (microridges or microplicae). The ectocervix and vaginal squamous cells presented a reduction in the number of their microridges and changes in the typical structural organization. These microtopographical results showed that the decline of estrogen during the menopause and postmenopause induces important and complex structural changes of the woman's reproductive system, much more detailed than those revealed to date by the use of only conventional optical and transmission electron microscopy (TEM). The three-dimensional findings offer the opportunity to re-evaluate the classic histopathology of the above aging organs using more refined microtopographical and morphophysiopathological parameters.

Cervix Uteri↗

PubMed1998

Ultrastructural dynamics of human testicular cords from 6 to 16 weeks of embryonic development. Study by transmission and high resolution scanning electron microscopy.

When the embryo is 6-week-old the gonad is composed mostly of migrating primordial germ cells, surface coelomic mesothelium and mesenchymal cells. At 7 weeks of gestation (wg) testicular cords consist of prespermatogonia, larger, with a more regular outline and higher mitotic activity than primordial germ cells, embraced by somatic pre-Sertoli cells. The morphofunctional development of Sertoli cells defines testicular differentiation. Towards 7.5 wg the gonad is finally in its differentiated stage; the basal lamina of the cords becomes distinguishable, testicular cords radially branch and elongate, and Leydig cells are clearly recognized. Primordial germ cells are large and spherical, with rounded and eosinophilic nuclei and large nucleoli. Pre-Sertoli cells, in turn, show round or columnar nuclei and rough endopasmic reticulum. Prespermatogonia and mostly pre-Sertoli cells actively proliferate. Many interdigitations and cytoplasmic processes are observed between neighboring pre-Sertoli cells and between pre-Sertoli cells and prespermatogonia. A sort of com partmentalization is established inside the cords in which pre-Sertoli cells tend to localize closer to the basal membrane embracing the prespermatogonia with long and thin cytoplasmic processes. Between 14 and 16 wg the most significant changes besides maximum development of Leydig cells are differentiation of mesenchymal cells around the cords into future peritubular cells and maturational changes of pre-Sertoli cells. These likely reveal a peak coinciding in time with reported increases in either testosterone production and Müllerian Inhibiting Substance secretion. During the period herein considered testicular cords show no lumen neither any sign of canalization so they cannot be termed "tubules".

Embryonic and Fetal Development↗

PubMed1997

Oxidative injury of synapse and alteration of antioxidative defense systems in rats, and its prevention by vitamin E.

In order to define whether active oxygen species actually induce oxidative damage to the nervous system, and how antioxidative defense systems are changed by oxidative stress, morphological and functional changes in the nervous system and antioxidant status were investigated. When rats were exposed to 100% oxygen in a chamber, many morphological changes, e.g. swollen astrocytes around vessels, deformed nuclei in nerve cells, pigmentation, swollen mitochondria, and abnormal accumulation of synaptic vesicles in swollen nerve terminals, were observed by electron microscopy. When synaptosomes isolated from oxygen-exposed rats were stimulated by KCl, acetylcholine release from the terminal was decreased more significantly than in synaptosomes from unexposed rats (P < 0.01). Synaptic plasma membrane fluidity decreased in response to oxygen exposure, and plasma membrane permeability to sucrose was increased significantly (P < 0.05). The cholesterol/phospholipid ratio of the plasma membranes was increased by oxidative stress and the content of unsaturated fatty acids, especially arachidonic acid and docosahexaenoic acid, decreased. The levels of thiobarbituric-acid-reactive substances in the plasma membranes of oxygen-exposed rats were significantly higher than in unexposed rats (P < 0.01). These results suggest that free radicals derived from oxygen may attack nerve terminals and peroxidize the plasma membrane. It was found that in response to the oxidative stress, the status of the defense system in synapse, i.e. the concentration of vitamin E, activities of superoxide dismutase and glutathione peroxidase changed, and that many of the changes observed were reduced remarkably by the intraperitoneal administration of vitamin E prior to stress. Data support the idea that vitamin E contributes to the protection against nerve dysfunction caused by oxidative stress.

Acetylcholine↗

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↗

PubMed1995

Ultrastructure of human Leydig cells at early gonadal embryogenesis.

The ultrastructure of human Leydig cells at different stages of the testicular prenatal development is described by means of transmission and scanning electron microscopy. Between 5 and 7 weeks of gestation (w.g.) the interstitial tissue of the gonad is filled with small undifferentiated mesenchymal cells, migrating primordial germ cells and blood vessels. When the embryo is 7 to 8 weeks-old Leydig cells (LC) appear in basically two morphological patterns, light and dark cells. Their most significative feature is the development of the smooth endoplasmic reticulum (SER) as a dense tubulo-vesicular network and the presence of numerous pleomorphic mitochondria with mainly lamellar cristae. At 14 and 16 w.g. the testicular interstitium reaches the maximum development; the cytoplasm of the LC shows a widespread network of anastomosing tubules of the SER and mitochondria with tubular cristae. Fetal LC show a partial cell coat, lack the crystals of Reinke, have few lipid droplets and show no signs of massive cell degeneration, at least until 16 w.g. These ultrastructural modifications in fetal LC are in accordance with the changes in both steroidogenic activity and hCG levels reported by the literature to occur at this stage of development. Junctional complexes were often observed among LC from 7 to 8 w.g. onwards.

Age Factors↗

PubMed1994

An ultrastructural study of epithelium differentiation in the human fetal fallopian tube.

The epithelial structure of the developing human fetal Fallopian tube has been studied systematically by parallel light, transmission and scanning electron microscopy. The specimens for this study were collected from spontaneous abortions at the 14th, 18th, 20th and 22nd weeks and from cases of intrauterine fetal death at the 24th and 31st weeks (hydrocephalus). The epithelium lining the wall of the female genital ducts was pseudostratified in a columnar fashion. It consisted of differentiating ciliated and microvillous cells and some degenerating elements. Microvillous cells-by far the most abundant in the early phases of tubal development-often showed a solitary cilium. Ciliated elements, though always less numerous than microvillous cells, were more densely concentrated on the developing fimbriae and at the uterotubal junction than in the ampulla. On the mucosal surface of the same regions, rounded intercellular holes delimited many crypts, from which ciliated elements sometimes sprouted. Notable aspects of cell proliferation and ciliogenesis were commonly observed and are likely to be related to circulating estrogens. These ultrastructural data indicate that the typical pattern of the adult oviduct is already sketched in fetal life. Furthermore, a strategic gathering of cilia was noted primarily at the sites of the developing oviduct, which will serve to mediate the passage of sperm and/or ova and promote fertilization in adult life.

Cell Differentiation↗

PubMed1994

Oocyte follicle cells association during development of human ovarian follicle. A study by high resolution scanning and transmission electron microscopy.

Morphodynamics of oocyte follicle cells association during the development of human ovarian follicles were studied by transmission electron microscopy and high resolution scanning electron microscopy including the ODO method. For this study primordial, primary, growing preantral and antral follicles were systematically analysed in a total of 20 adult and fetal (3-8 months and at term) ovaries. In early stages of follicle development (primordial and primary stages) the flattened and/or polyhedral cells, closely associated with the growing oocyte, project an increasing number of microvillous processes. These are in apposition with the oolemma, and form bulbous terminals presenting attachment zones such as zonula adherens, desmosomes and communicating junctions (gap junctions). "Focal contacts" between oolemma, and lateral microvillous extensions of follicle cells were also present. Unusual forms of contact between follicle cell microvilli and oocytes in the early stages of growing primordial and primary follicles were also observed. These consist of long, thin extensions penetrating into the oocyte through deep invaginations of the oolemma. The aid of high resolution SEM of specimens subjected to the ODO method clearly reveals their 3-D arrangement within the ooplasm. They appear as long tortuous microvilli coming very close to the nucleus, and in their course are closely associated with a variety of organelles such as Golgi vesicles, endoplasmic reticulum membranes and nascent forms of smooth endoplasmic reticulum. Using integrated observations by TEM and SEM, there may be as many as 3-5 "intraooplasmic processes" even in only one plane of fracture of an oocyte. Therefore, if the total volume of the oocyte and associated cells is considered, their amounts appear to be higher than previously reported. Thus, they have to be considered as normal devices of deep contact between the ooplasm and associated follicle cell extensions. The presence of such structures within the ooplasm in early developing follicles well coincides with the great increase in volume of the oocyte. Although it is commonly believed that the activation of the growing oocyte may depend on the numerous contacts between the oolemma and follicle cells (mostly via gap junctions), the finding of these additional intraoocytic extensions suggests that they may in someway contribute to the initiation of growth in the human. In fact, these microvilli penetrate deep into the ooplasm, much like a sword in its sheath.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

PubMed1992

A new approach to the study of ovarian follicles by scanning electron microscopy and ODO maceration.

The ultrastructure of the follicle-oocyte complex in rodents and humans was revealed by high resolution scanning electron microscopy (SEM) following the Osmium-DMSO-Osmium maceration method (TANAKA and NAGURO, 1981). In primary follicles, the majority of oocyte organelles such as mitochondria and Golgi complex components are concentrated in a juxtanuclear area. In particular, many spherical mitochondria are oriented all around the nucleus. After maceration of the ooplasm matrix, most of these mitochondria appear intermingled with numerous microtubules (MT) and associated with many Golgi vesicles. Such a nuclear polarization of organelles, essential to the oocyte metabolism, might depend upon a MT activity. MT might guide mitochondria to gather in the perinuclear region and further maintain their close associated to the nuclear envelope. A similar relationship among microtubules, vesicular Golgi complex and mitochondria has been also observed when, in maturing oocytes, these organelles migrate and gather in other areas of the ooplasm. A pattern common only to human developing follicles appears in the occurrence of long microvilli projected from follicle cells deep into the oocyte. These unusual microvilli running within the ooplasm are surrounded by several vesicles of the Golgi complex and endoplasmic reticulum, and often end close to the nucleus. In the antral follicle, the microvilli of corona cells, directed toward the oocyte (after their full exposure through the chemical dissolution of the zona pellucida matrix) are extremely numerous (up to 70/cell), long (up to 7/10 microns) and tortuous. They resemble epididymal stereocilia, may be ramified and possess bulbous tips. In contrast, oocyte microvilli are thin and short.(ABSTRACT TRUNCATED AT 250 WORDS)

Dimethyl Sulfoxide↗