Lakhasly

Unfortunately, the same end points were not examined in ovarian fragments and cultured follicles, no rotational control group was included, and the number of replicates per group and other experimental details were not provided.By contrast, exposure to either simulated microgravity or simulated hypergravity lengthened oestrous cycles due to lengthened dioestrous, whereas space flight resulted in cessation of cycling, suggesting that other exposures (such as stress or circadian rhythm disruption) during space flight besides microgravity affect the hypothalamic-pituitary-ovarian axis. By contrast, nearly 40% of morula or early blastocyst stage embryos cultured in simulated microgravity progressed to the expanded blastocyst stage by 48 h. Both simulated microgravity and rotational control morula or early blastocyst stage embryos had upregulation of SAPK (a stress-activated protein kinase) phosphorylation at Thr183 or Thr185, a marker for activation of SAPK signalling, after 24h of culture compared with static controls; all of these effects were similar but less severe in rotation controls than in animals in simulated microgravity. As a result of the similarity of lengthened vaginal dioestrous during microgravity with lengthened vaginal dioestrous during pseudopregnancy in rodents (which is elicited by cervical stimulation that causes a surge of prolactin secretion), suppression of prolactin secretion was tested and found to block the induction of lengthened dioestrous by hypergravity52.Exposure of pregnant rats to hypergravity during the second half of gestation did not alter gestation length, duration of parturition (time from birth of first pup to birth of last pup), litter size or birth weights; however, the frequency of lordosis contractions during labour decreased by half45 and neonatal pup mortality was increased in rats exposed to hypergravity46,59. Oocytes were harvested at the germinal vesicle stage (which is the metaphase of the first meiotic division) from immature Kunming mice 48h after injection of 7.5IU equine chorionic gonadotropin to stimulate development of a cohort of preovulatory follicles.This finding under microgravity was related to abnormal meiotic spindle formation during both the first and second meiotic divisions, with abnormal localization of ?-tubulin (which is essential for spindle formation) around the chromosomes of oocytes cultured in simulated microgravity.Exposure of female and male mice to hypergravity before mating and through gestation decreased pregnancy rates up to 2.9g (with no pregnancies at 3.5 g), decreased fetal size and altered skeletal development (the longest dimension of most bones measured was increased at 2.3 g, the longest dimension and perimeter of most bones were decreased at 2.6g and these parameters were decreased for all bones at 2.9 g) compared with 1 g controls48.Rather, decreased neonatal survival of pups born to dams exposed to hypergravity was associated with decreased glucose oxidation and lipogenesis in mammary glands, decreased size of adipocytes with decreased rate of lipolysis and an increased rate of glucose incorporation into lipids in the liver53.Fertilization of mouse oocytes occurred normally under microgravity simulated using a 3D clinostat; however, continued culture under microgravity resulted in delayed development to the blastocyst stage and fewer trophectoderm cells in those embryos that reached the blastocyst stage compared with embryos at normal gravity57.No differences in mating ability or gestation length were observed in rats adapted to hypergravity (2.2g or 3.1g), but the number of fetuses and maternal care of pups were dose-dependently decreased compared with those of 1g controls50.In other work, luteal cells from the corpora lutea of pregnant rats were cultured in microgravity simulated using a high aspect ratio vessel and compared with cells from spinner flask controls or in microgravity simulated using a clinostat with static controls.Luteal cells cultured in the clinostat model for 2 days had increased DNA damage as measured by the Comet assay, increased apoptosis and decreased numbers of active mitochondria compared with static controls42.In contrast to the abnormal organization of microtubules, microfilament organization and function, which are necessary for migration of the chromosomes and spindles to the periphery of the oocyte, were not disrupted under simulated microgravity55.Preimplantation development of mouse embryos has also been investigated using a rotary cell culture system with high aspect ratio culture vessels to simulate microgravity compared with static culture controls and rotation controls58.Luteal cells cultured in both microgravity models exhibited decreased progesterone secretion compared with their respective control cultures during up to 8 days of culture42,43.Moreover, exposure to hypergravity for >=8 h during the dioestrous phase of the oestrous cycle, but not during other cycle stages, induced a surge of prolactin secretion49.

Unfortunately, the same end points were not examined
in ovarian fragments and cultured follicles, no rotational
control group was included, and the number of replicates per group and other experimental details were not
provided. Therefore, although the results of this study
suggest that microgravity has an adverse effect on growth
and development of secondary follicles, these results
need to be confirmed in future studies.
The effects of simulated microgravity on maturation
of oocytes were investigated using a rotary cell culture
system with high aspect ratio culture vessels to reduce
shear stress55. Oocytes were harvested at the germinal
vesicle stage (which is the metaphase of the first meiotic
division) from immature Kunming mice 48h after injection of 7.5IU equine chorionic gonadotropin to stimulate development of a cohort of preovulatory follicles. The
oocytes were then cultured in a medium supplemented
with FSH, LH and oestradiol for up to 16h in simulated
microgravity or at normal gravity in static culture (control
group). No rotational control group was included to control for shear forces, turbulence and vibrations. Meiosis
resumption, as assessed by breakdown of the oocyte
nuclear envelope, did not differ between the two groups.
However, the percentage of oocytes that reached metaphase of the second meiotic division, assessed as the presence of extrusion of the first polar body, was 73% under
1 g but only 9% under microgravity. Moreover, 13% of
oocytes cultured under microgravity showed cytoplasmic
projections or blebbing, whereas these features were rare
(