Investigating nurses' quality of life and work-life balance statuses in Singapore.

AIMS: To investigate the key determinants of nurses' quality of life and work-life balance statuses in a tertiary hospital in Singapore. BACKGROUND: Nurses' quality of life can directly and indirectly impact patients' safety and quality of care. Therefore, identifying key factors that influence nurses' quality of life is essential in the healthcare delivery system. METHODS: A descriptive quantitative study design was adopted, and validated questionnaires were used. Data were collected in a period of 3 months (March to May 2014) at a 600-bed tertiary hospital in Singapore. One thousand and forty nurses participated in the study. RESULTS: Social support and sense of coherence were found to be significant predictors for high quality of life in all domains. Most nurses in this study spent more time on work than their private lives. However, there was no significant difference in job satisfaction among the four groups of nurses' proportions of percentages of actual time spent on work and private life. CONCLUSIONS: Cultivating social support from family, friends/colleagues and supervisors can help an individual cope with stress and enhance a nurse's quality of life. IMPLICATIONS FOR NURSING POLICY AND PRACTICE: Even though nurses who spent more time at work were still satisfied with their job, they might need to be aware of their physical health and work environment. Nursing policy related to nurses' physical health and environment should be established. Health promotion programmes such as physical exercise and mindfulness interventions should be conducted to promote nurses' well-being and healthy workplace environments to enhance nurses' quality of life.

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.

Elimination of germ cells during differentiation of the human ovary: an electron microscopic study.

Observations by scanning and transmission electron microscopy during ovarian development (from 7 wk until term of gestation) showed numerous germ cells within the superficial epithelial layer covering the ovary. In early stages of differentiation (between 7 and 11 wk), germ cells appeared to be actively migrating to the surface of the ovary by ameboid-like movements. Later, the transfer of the germ cells to the surface epithelium was also occurring passively, as a consequence of an intense proliferation of germ and somatic cells - arranged in clusters and cords - migrating towards the most superficial areas of the ovary. The present evidence suggests that a number of primordial germ cells - as well as oogonia and oocytes - which lie in the superficial epithelium can leave the ovary and ultimately rest freely upon its surface. Elimination of germ cells during differentiation of the ovary in humans was always paralleled by necrosis of oogonia and oocytes and atretic alteration of primitive follicles. The significance of these processes is discussed in relation to the reduction of the pool of oocytes at birth.

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.

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.

Scanning electron microscopy of nonfunctional human ovaries.

Samples of ovaries taken from fertile and infertile patients, 23 to 32 years of age, were fixed in 2.5% buffered glutaraldehyde, processed by critical point drying, sputter coated with gold palladium and viewed by scanning electron microscopy. Cell cores proliferating from the tunica albuginea into the stroma were made up of an epithelium similar to that covering the ovarian surface. Ovarian papillae, arising from the ovarian surface, were covered with typical polyhedral superficial cells. The oocyte and granulosa cells were connected by means of microvilli, desmosomes and gap junctions. After ovulation the stigma was occupied by a mass of connective tissue to which were attached red blood cells (coagulated blood) and residual follicle cells. In the postovulatory follicle the adjacent superficial epithelium underwent extensive proliferation to repair the rupture point. The anovulatory ovaries were completely covered with superficial epithelium, which was packed tightly and exhibited dense microvilli, blebs, solitary cilia, ruffles, filopodia and different types of cytoplasmic projections. This was in contrast to the ovulatory ovary, in which the superficial epithelium seemed to be localized only in certain areas and the site of the follicular rupture was not completely repaired by superficial epithelium.

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.

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.

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.

Surface ultrastructure of polycystic ovaries as viewed by electron microscopy.

Scanning electron microscopy was used to observe surface fine structure of germinal epithelium and granulosa cells of human ovaries from 24 patients with polycystic ovaries and primary infertility. Synthetic LH-RH was administered intravenously and serum LH was measured at frequent intervals before and after LH-RH injection. The PCO patients were arbitrarily classified into two groups on the basis of ovarian morphology: typical PCO (Type I) with greater LH response than the lower LH response of a typical PCO (Type II). The germinal epithelium which did not completely cover the surface of the normal ovary was characterized by patchy areas of cells with and without dense microvilli. In normal preovulatory follicles, most granulosa cells were polyhedral in shape with smooth surfaces, whereas those facing the follicular cavity were elongated and flattened and were covered with material having a filamentous/reticular texture. In PCO the germinal epithelium surrounding the whole surface possessed dense microvilli, solitary cilia, and blebs, resembling the fetal ovary. In normal ovaries, the follicular cells were uniform in size and shape with microvilli and evaginations. The PCO cells have irregular size and shape with few microvilli.

Germ cells in the ovarian surface during fetal development in humans. A three-dimensional microanatomical study by scanning and transmission electron microscopy.

Observations by correlated scanning and transmission electron microscopy during human ovarian development (from 7 weeks to delivery) have revealed germ cells in the surface epithelium of the ovary. During embryonal differentiation (7/8 weeks) and in early stages of fetal development (9-12 weeks) the ameboid features of some primitive germ cells occurring in the cortical areas of the ovary, would suggest their capability to move and possibly migrate to the superficial coelomic layer covering the gonad. Subsequently the germ cells, gradually transformed in clusters of dividing oogonia and further meiotic oocytes, were closely associated to proliferating somatic cells of sexual cords and often resulted passively pushed and consequently dislocated in the most superficial areas of the ovary. As a result of these intense morphogenetic processes--even when the ovary was fully developed--the germ cells which were early in these superficial areas became included in the surface epithelium of the ovary. Therefore, through all stages of ovarian development and from these areas, germ cells were extruded on the surface of the gonad and ultimately liberated in the peritoneal cavity. Since germ cells were found within the surface epithelium of the ovary even in two newborns, and since some of these oocytes were eliminated from the ovary, it is possible that this extrusion mechanism might even continue to operate during the period between birth and puberty. On the other hand germ cells that in early stages had been more deeply located in the ovarian tissues, closely associated with the proliferating sex cords, maintained this relationship and became later incorporated in primitive follicles. Present evidence suggests that the above morphodynamics can be most likely depending upon a special tropism of germ cells towards the epithelioid components of the surface epithelium and mesonephric cords of the developing ovary. This close and early relationship between somatic and germ components is recognized as crucial to further development and fate of germ cell population in human ovary.

Development of the ovarian surface and associated germ cells in the human fetus. A correlated study by scanning and transmission electron microscopy.

The ovarian surface and associated germ cells have been studied in human fetuses from 12 weeks of age until near term, using light, TEM and SEM techniques. The surface epithelium and related cords proliferate extensively, especially at midterm. The cords of the ovarian cortex appear to be linked with ingrowths from the surface epithelium, and both structures have a common basal lamina. Germ cells are always interspersed among the somatic cells of the surface epithelium and associated cords. These results indicate that both the proliferating cords and surface epithelium may contribute to the formation of early follicles. Furthermore, the occurrence, of elements having some of the features of primitive steroidogenic cells in the regions of cord-surface epithelium continuity, suggests that both structures (surface epithelium and cords) contribute somatic cells, which in addition to becoming granulosa cells, might also contribute to the provision of primitive interstitial cells. Gonocytes tend to migrate through the developing ovarian tissue towards the surface where they become extruded into the peritoneal cavity. This phenomenon might contribute to the reduction in the number of germ cells at birth and parallels the atretic processes within the ovary.

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)

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)

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.

Surface ultrastructure of functional and nonfunctional human ovaries.

Biopsies of human ovaries from functional and nonfunctional polycystic ovary patients 24 to 56 years of age were processed by critical point drying and viewed by scanning electron microscopy. The superficial epithelium was characterized by polyhedral-shaped cells with abundant evenly distributed apical microvilli with some intercellular connection and occasional solitary cilia. The fine structure modifications in the ovarian superficial epithelium (e.g., microvilli, blebs, ruffles, and micropapillae) reflect physiological changes in cell cycle or reproductive cycle. Dramatic changes were noted in the superficial epithelium of polycystic, atrophic, and sclerotic ovaries: distribution of microvilli, proportion of cells of different morphology, abundance of solitary cilia, blebbing, and the size of rufflings. In developing follicles, the granulosa cells were spherical and/or polyhedral in shape and in close contact. In atretic follicles, the granulosa cells were flattened and very irregular in shape without cytoplasmic evaginations. The loss of such evaginations within the atretic follicles may correspond to functional changes, e.g., inability to bind and respond to gonadotropic receptors. Follicles in polycystic ovaries were characterized by the disruption of the granulosa layer. Thus, areas of the follicle were devoid of any granulosa cells and appeared patchy, whereas the granulosa cells were irregular in size and shape.

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".

The ultrastructure of human reproduction. I. The natural history of the female germ cell: origin, migration and differentiation inside the developing ovary.

This presentation, on both printed copy and CD-ROM, summarizes a series of original data on the ultrastructure of human reproduction produced by our research group. In particular, female germ cell behaviour at the time of migration and colonization of the gonad and germ-somatic cell interactions inside the developing ovary are reviewed from a morphodynamic point of view. The results mostly consist of black-and-white transmission and scanning electron microscopy (TEM and SEM) images. Artificially coloured SEM pictures, light microscopy images and drawings have also been selected for iconography to render complex microanatomical details and their morphofunctional relationships more comprehensible. In all, 35 images are presented in this article, each related to a concise text section and accompanied by a self-explaining caption. A list of pertinent references is also provided.

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".

The fetal development of the human uterine cervix from the 12th to the 31st postmenstrual week as revealed by scanning electron microscopy. Anatomical and clinical correlations.

To clarify the differentiation of the human uterine cervix, fetuses of the 12th, 15th, 18th, 20th, 21st, 22nd, and 31st postmenstrual week were studied by Scanning Electron Microscopy. At the 12th week the endocervical epithelium consisted of microvillous cells, often showing single cilia and anlages of tubular glands. At the 15th week the cervical canal was entirely formed and its surface cells appeared columnar. At the 18th week these cells were replaced by flat or slightly raised cells, provided with thin microplicae. At the 20th week the endocervical epithelium appeared pseudostratified with higher, apically-convex and shorter basal cells; glands developed in form of tubular invaginations of the luminal epithelium. At the 21st week in the lower part of the endocervix polymorphic, globose cells with short and stubby microvilli and others elongated, having short microplicae, were observed. These latter likely corresponded to the so-called columnar cells undergoing squamous metaplasia. Among microvillous and/or metaplastic cells, a number of apoptotic cells, as globose elements with a ruffled and invaginated surface, were also noted. At the 22nd week evident plicae palmatae were found, covered by microvillous secreting cells. These showed smooth bulged apices releasing droplets by a "micro-apocrine" mechanism. These features increased at the 31st week, when many droplets were noted also around the mouth of the cervical glands. Only at this phase of development fully ciliated cells were found often contacting secretory material. Mature squamous exfoliating cells with complex microplicae covered an hypertrophied portio vaginalis. The squamous cells extended toward a squamo-columnar junction in form of flat, tongue-like projections. Their tips consisted of immature squamous metaplastic cells, which were endocervical columnar progressively becoming elongated elements, exhibiting short microvilli. The above features are rather similar to those occurring during the adult reproductive age. Therefore, it might be hypothesized that, during pregnancy, a common gestational hormonal background may induce somewhat similar morpho-dynamic processes in the cells and tissues of the fetal reproductive tract mimicking what occurs in the adult female.