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.

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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.

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.

This study investigated the status of work-life imbalance among hospital nurses in Japan and impact of work-life imbalance on job satisfaction and quality of life. A cross-sectional survey of 1,202 nurses (81% response rate) was conducted in three Japanese acute care hospitals. Participants were divided into four groups for actual work-life balance (Group A: 50/50, including other lower working proportion groups [e.g., 40/50]; Group B: 60/40; Group C: 70/30; and Group D: 80/20, including other higher working proportion groups [e.g., 90/10]). We also asked participants about desired work-life balance, and private and work-related perspectives. Satisfactions (job, private life, and work-life balance), quality of life, and stress-coping ability were also measured. All data were compared among the four groups. Most nurses sensed that they had a greater proportion of working life than private life, and had a work-life imbalance. Actual WLB did not fit compared to desired WLB. When the actual working proportion greatly exceeds the private life proportion, nurses’ health could be in danger, and they may resign due to lower job satisfaction and QOL. Simultaneous progress by both management and individual nurses is necessary to improve work-life imbalance.

The aim of this article is to summarize and update, through an integrated analysis by transmission electron microscopy (TEM) and high resolution scanning electron microscopy (SEM) after osmium-dimethyl sulfoxide-osmium (ODO) maceration, the studies of our research group on the morphodynamics of oocyte-follicle cell associations during follicle development in humans. In resting oocytes, follicular cells project few and short cytoplasmic processes in the perioocytic space. They often form bulbous terminals very close to the oolemma where zonulae adherentes, maculae adherentes, and gap junctions are present. The oolemma mostly appears smooth with short and scanty microvilli. In early growing follicles, follicular cell projections appear as (a) long and tortuous microvilli or (b) large and short extensions. The oolemma shows numerous short microvilli. By TEM, long and thin follicular "intraooplasmic processes" have been seen to penetrate deeply into some oolemma invaginations. In macerated samples, they are observed by SEM to come very close to the nucleus and contact different oocyte organelles. These processes are more likely involved in early oocyte growth. In late growing follicles, oocyte-somatic cell interactions-now established through the interposition of the zona pellucida (ZP)-preserve the general features of early growth stage, with the exceptions of "intraooplasmic processes," which are no more present. In mature follicles subjected to a long ODO maceration, corona cells appear to contact the oocyte through an apical plume of numerous very long "curly hair-like microvilli." Corona cell microvilli, quite likely provide a sort of cytoplasmic skeleton for the ZP and they are possibly involved in (a) release of nutrients or removal catabolites to/from oocyte and vice versa and (b) transfer of substances to build up ZP. In conclusion, among oocyte and somatic cells a structural and functional association is revealed. This association, certainly highly dynamic in vivo, plays a key role in regulating the healthy folliculogenesis to assure a correct and timed oocyte maturation and ovulation.

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