Reproduction
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Molecular regulation of spermatogonial stem cell renewal and differentiation The intricate molecular and cellular interactions between spermatogonial stem cells (SSCs) and their cognate niche form the basis for life-long sperm production. To maintain long-term fertility and sustain sufficiently high levels of spermatogenesis, a delicate balance needs to prevail between the different niche factors that control cell fate decisions of SSCs by promoting self-renewal, differentiation priming or spermatogenic commitment of undifferentiated spermatogonia (Aundiff ). Previously the SSC niche was thought to be formed primarily by Sertoli cells. However, recent research has indicated that many distinct cell types within the testis contribute to the SSC niche including most somatic cell populations and differentiating germ cells. Moreover, postnatal testis development involves maturation of somatic supporting cell populations and onset of cyclic function of the seminiferous epithelium. The stochastic and flexible behavior of Aundiff further complicates the definition of the SSC niche. Unlike in invertebrate species, providing a simple anatomical description of the SSC niche in the mouse is therefore challenging. Rather, the niche needs to be understood as a dynamic system that is able to serve the long-term reproductive function and maintenance of fertility both under steady-state and during development plus regeneration. Recent data from us and others have also shown that Aundiff reversibly transition between differentiation-primed and self-renewing states based on availability of niche-derived cues. This review focuses on defining the current understanding of the SSC niche and the elements involved in its regulation.
Reproduction - Tập 158 Số 5 - Trang R169-R187 - 2019
Absence of mDazl produces a final block on germ cell development at meiosis The autosomal gene DAZL is a member of a family of genes (DAZL, DAZ, BOULE), all of which contain a consensus RNA binding domain and are expressed in germ cells. Adult male and female mice null for Dazl lack gametes. In order to define more precisely the developmental stages in germ cells that require Dazl expression, the patterns of germ cell loss in immature male and female wild-type (+/+, WT) and Dazl -/- (DazlKO) mice were analysed. In females, loss of germ cells occurred during fetal life and was coincident with progression of cells through meiotic prophase. In males, testes were recovered from WT and DazlKO males obtained before and during the first wave of spermatogenesis (days 2-19). Mitotically active germ cells were present up to and including day 19. Functional differentiation of spermatogonia associated with detection of c-kit positive cells did not depend upon expression of Dazl. RBMY-positive cells (A, intermediate, B spermatogonia, zygotene and preleptotene spermatocytes) were reduced in DazlKO compared with WT testes. Staining of cell squashes from day 19 testes with anti-gamma-H2AX and anti-SCP3 antibodies showed that germ cells from DazlKO males were unable to progress beyond the leptotene stage of meiotic prophase I. It was concluded that in the absence of Dazl, germ cells can complete mitosis, and embark on functional differentiation but that, in both sexes, progression through meiotic prophase requires this RNA binding protein.
Reproduction - Tập 126 Số 5 - Trang 589-597 - 2003
In-vivo and in-vitro effects of ethanol on mouse preimplantation embryos
Reproduction - Tập 80 Số 1 - Trang 49-57 - 1987
Melatonin deprival modifies follicular and corpus luteal growth dynamics in a sheep model This study assessed the effect of melatonin deprival on ovarian status and function in sheep. Experimental procedures were carried out within two consecutive breeding seasons. Animals were divided into two groups: pinealectomised (n =6) and sham-operated (n =6). The completeness of the pineal gland removal was confirmed by the plasma concentration of melatonin. Ovarian status was monitored by ovarian ultrasonography for 1 year to study reproductive seasonality. Follicular and corpus luteal growth dynamics were assessed during an induced oestrous cycle. As the effects of melatonin on the ovary may also be mediated by its antioxidant properties, plasma Trolox equivalent antioxidant capacity (TEAC) was determined monthly for 1 year. Pinealectomy significantly extended the breeding season (310±24.7 vs 217.5±24.7 days in controls;P <0.05). Both pinealectomised and sham-operated ewes showed a well-defined wave-like pattern of follicle dynamics; however, melatonin deficiency caused fewer waves during the oestrous cycle (4.3±0.2 vs 5.2±0.2;P <0.05), because waves were 1 day longer when compared with the controls (7.2±0.3 vs 6.1±0.3;P <0.05). The mean area of the corpora lutea (105.4±5.9 vs 65.4±5.9 mm2 ;P <0.05) and plasma progesterone levels (7.1±0.7 vs 4.9±0.6 ng/ml;P <0.05) were significantly higher in sham-operated ewes compared with pinealectomised ewes. In addition, TEAC values were significantly lower in pinealectomised ewes compared with control ones. These data suggest that melatonin, besides exerting its well-known role in the synchronisation of seasonal reproductive fluctuations, influences the growth pattern of the follicles and the steroidogenic capacity of the corpus luteum. Free Italian abstract An Italian translation of this abstract is freely available athttp://www.reproduction-online.org/content/147/6/885/suppl/DC1 .
Reproduction - Tập 147 Số 6 - Trang 885-895 - 2014
Carbohydrate mediation of boar sperm binding to oviductal epithelial cells in vitro After mating, mammalian spermatozoa are transported to the lower oviductal isthmus. Spermatozoa are sequestered at the isthmus by attaching and interacting with oviductal epithelial cells, hence forming a sperm reservoir. In several mammalian species, specific carbohydrates mediate sperm-oviductal epithelial cell binding. A quantitative in vitro free cell bioassay was developed to investigate the involvement of carbohydrate recognition in pig sperm-oviductal epithelial cell interactions. This assay was validated. The sensitivity of the assay was such that it was possible to discriminate between different sperm concentrations and sperm-oviductal epithelial cell co-incubation periods, spermatozoa with damaged plasma membranes and epithelial cells of non-reproductive origin. Optimal conditions were used to incubate spermatozoa and oviductal epithelial cells in the presence of six hexose sugars at concentrations of 0, 2, 10 and 50 mmol l(-1). A significant (P < or = 0.05) reduction in the binding of spermatozoa to the oviductal epithelium was detected with 2, 10 and 50 mmol maltose l(-1), 50 mmol lactose l(-1) and 50 mmol mannose l(-1). These findings support the hypothesis that attachment of pig spermatozoa to oviductal epithelium before fertilization is mediated by carbohydrate recognition.
Reproduction - Tập 122 Số 2 - Trang 305-315 - 2001
Factors in seminal plasma of bulls that affect the viability and motility of spermatozoa
Reproduction - Tập 68 Số 2 - Trang 275-280 - 1983
Effects of seminal vesicle fluid components on sperm motility in the house mouse
Reproduction - Tập 83 Số 1 - Trang 169-176 - 1988
Development of an assay to assess the functional integrity of the human sperm membrane and its relationship to other semen characteristics
Reproduction - Tập 70 Số 1 - Trang 219-228 - 1984
VARIATIONS IN PLASMA LH LEVELS DURING THE OVULATORY CYCLE OF THE HEN, GALLUS DOMESTICUS
Reproduction - Tập 35 Số 3 - Trang 561-564 - 1973
LYSOSOMAL ENZYMES IN THE ACROSOME AND THEIR POSSIBLE ROLE IN FERTILIZATION
Reproduction - Tập 21 Số 3 - Trang 501-515 - 1970
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