نتایج جستجو برای: headed sperm cells

تعداد نتایج: 1418975  

2013
Gunasekaran Krishnamoorthy Kandaswamy Selvakumar Prabhu Venkataraman Perumal Elumalai Jagadeesan Arunakaran

Sertoli cell proliferation is attenuated before attaining puberty and the number is fixed in adult testes. Sertoli cells determine both testis size and daily sperm production by providing physical and metabolic support to spermatogenic cells. Polychlorinated biphenyls (PCBs) exposure disrupts functions of Sertoli cells causing infertility with decreased sperm count. On the other hand, lycopene ...

Journal: :Human reproduction 2004
J Erenpreiss K Jepson A Giwercman I Tsarev Je Erenpreisa M Spano

BACKGROUND Sperm DNA integrity (SDI) is an important factor in the prognosis of male fertility. Here we compare the toluidine blue (TB) image cytometry test, recently proposed by us for SDI assessment, with two other tests-the sperm chromatin structure assay (SCSA) and the terminal nick-end labelling (TUNEL) assay. METHODS Sperm samples from 35 men were evaluated for standard sperm parameters...

2015
Sandhya Anand Hiren Patel Deepa Bhartiya

BACKGROUND Extensive research is ongoing to empower cancer survivors to have biological parenthood. For this, sperm are cryopreserved prior to therapy and in younger children testicular biopsies are cryopreserved with a hope to mature the germ cells into sperm later on for assisted reproduction. In addition, lot of hope was bestowed on pluripotent embryonic and induced pluripotent stem cells to...

Journal: :Plant physiology 2008
Filipe Borges Gabriela Gomes Rui Gardner Nuno Moreno Sheila McCormick José A Feijó Jörg D Becker

In flowering plants, the two sperm cells are embedded within the cytoplasm of the growing pollen tube and as such are passively transported to the embryo sac, wherein double fertilization occurs upon their release. Understanding the mechanisms and conditions by which male gametes mature and take part in fertilization are crucial goals in the study of plant reproduction. Studies of gene expressi...

2017
Sung Woo Kim Byung Chul Jee Seul Ki Kim Seok Hyun Kim

Objective The aim of this study was to compare the efficacy of swim-up and density gradient centrifugation (DGC) for reducing the amount of sperm with fragmented DNA, sex chromosome aneuploidy, and abnormal chromatin structure. Methods Semen samples were obtained from 18 healthy male partners who attended infertility clinics for infertility investigations and were processed with swim-up and D...

Journal: :Communicative & Integrative Biology 2015

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2013
Clinton T Morgan Daniel Noble Judith Kimble

Germ cell fate decisions are poorly understood, despite their central role in reproduction. One fundamental question has been whether germ cells are regulated to enter the meiotic cell cycle (i.e., mitosis-meiosis decision) and to be sperm or oocyte (i.e., sperm-oocyte decision) through one or two cell fate choices. If a single decision is used, a male-specific or female-specific meiotic entry ...

Journal: :Development 2002
Noriyoshi Sakai

Because cell culture systems are easily accessible for experimental genetic manipulation, male germ cell culture is of great usefulness in creating sperm vectors. This report describes that cultured male germ cells of zebrafish (Danio rerio) underwent mitosis and transmeiotic differentiation, including the entire process of meiosis, to develop into functional sperm. Enzymatically dissociated te...

Journal: :The Plant cell 1994
H. S. Yu S. D. Russell

Tobacco sperm cells contain intact mitochondria within their nuclei with a frequency of 0.35 [plusmn] 0.13 per cell. These inclusions appear to originate from mitochondria found among chromatids in the highly elongated metaphase plate of the dividing generative cell. These organelles are apparently captured during the reconstitution of the nuclear envelope. Only sperm cells were observed to con...

Journal: :The Plant journal : for cell and molecular biology 2003
Michele L Engel Annie Chaboud Christian Dumas Sheila McCormick

Although double fertilization in angiosperm was discovered in 1898, we still know nothing about the proteins that mediate gamete recognition and fusion in plants. Because sperm are small and embedded within the large vegetative cell of the pollen grain, mRNAs from sperm are poorly represented in EST databases. We optimized fluorescence-activated cell sorting (FACS) in order to isolate Zea mays ...

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