نتایج جستجو برای: haploid spermatids
تعداد نتایج: 7038 فیلتر نتایج به سال:
Haploid cells in rat kangaroo corneal endothelium cultures and x-ray-induced chromosome aberrations.
N the reproduction of mammals? germ cells undergo two maturation divisions I to yield haploid gametes which, through union with gametes from the opposite sex, give rise to the next generation. Based on the existence of haploid status in gametes, investigators in the 1940’s and 50’s experimentally induced haploid cells in parthenogenetically developed blastocysts or in very early embryos of rabb...
ELECTRON MICROSCOPIC STUDY OF THE GOLGI ZONE OF THE RAT SPERMATIDS REVEALED TWO MAIN TYPES OF VESICULAR STRUCTURES: flat vesicles generally accumulated in stacks and spheroidal vesicles of various sizes. The Golgi zone of young spermatids showed a predominance of flat vesicles and small spherical vesicles, while the "residual" Golgi zone of the maturing spermatids displayed an increased number ...
proposed that could activate transcription of numerous genes in spermatids. If a gene is transcribed and its protein accumulates in spermatids, it is very possible that the protein will function there. Regulation of holoenzyme levels might also contribute to other cases of cell-type-specific gene regulation. Although no other cells seem to accumulate as much of the basal transcription machinery...
Male germ cell differentiation is a highly regulated multistep process initiated by the commitment of progenitor cells into meiosis and characterized by major chromatin reorganizations in haploid spermatids. We report here that a single member of the double bromodomain BET factors, Brdt, is a master regulator of both meiotic divisions and post-meiotic genome repackaging. Upon its activation at ...
BACKGROUND The use of testicular sperm in assisted reproduction depends on the availability of sperm in wet preparations. It is not always possible to recover sperm from the testis, even with previous sperm-positive histopathological findings. The purpose of this study was to evaluate the sperm-negative wet preparation search results with flow cytometric ploidy analysis and histopathological ex...
The fresh water catfish is the most predominant species of the teleost bred in captivity in Nigeria and has provided a model for the study of reproduction in aquatic vertebrates, but information on the number of mitotic divisions and spermatogonial generations remains inconclusive. This investigation aimed at assessing the number of generations of spermatogonia produced prior to meiotic divisio...
Unwanted childlessness affects approximately one in six couples worldwide. According to the World Health Organization, in nearly 40% of cases the cause can be attributed to the female, in 20% to the male, in 25% to both, and in 15% the cause remains unknown. The incidence of male factor infertility in the general population is approximately 7%. The majority of these men experience irreversible ...
During spermiogenesis, haploid round spermatids undergo dramatic cell differentiation and morphogenesis to give rise to mature spermatozoa for fertilization, including nuclear elongation, chromatin remodeling, acrosome formation, and development of flagella. The molecular mechanisms underlining these fundamental processes remain poorly understood. Here, we report that MNS1, a coiled-coil protei...
The production of tubular fluid (TF) and interstitial fluid (IF) in normal and irradiated testes was compared in the same growing rats submitted at 25 days of age to unilateral, scrotal X-ray, exposure. Twelve rats were sacrificed each week from 32 to 81 days of age. In both normal and irradiated testes, IF increased in parallel with the testicular weight until 67 days of age and declined sligh...
Chimpanzees and humans are genetically very similar, with the striking exception of their Y chromosomes, which have diverged tremendously. The male-specific region (MSY), representing the greater part of the Y chromosome, is inherited from father to son in a clonal fashion, with natural selection acting on the MSY as a unit. Positive selection might involve the performance of the MSY in spermat...
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