منابع مشابه
chromosomal & cytogenetic : studies in a case of klinefelters syndrome
a 21 year old boy was first seen because of gynecomastia and primary hypogonadisme. a biopsy specimen from the testes revealed hyalinization of the seminiferous tubules with spermatogenic arrest, and tissue studies showed positive sex chromatin and the karyotype was 47 (xyy).
متن کاملMeiosis
Why should a biologist care about rheology? Actually, biologists used to care a lot more about rheology than they have lately. A prominent physiology text from the 1950s (An outline of general physiology by L. Heilbrunn) stated that “In any attempt to interpret the machinery of a living cell, it is essential to know something about the mechanical properties of the protoplasm in the cell that is...
متن کاملMeiosis.
Sexual reproduction requires the production of haploid gametes (sperm and egg) with only one copy of each chromosome; fertilization then restores the diploid chromosome content in the next generation. This reduction in genetic content is accomplished during a specialized cell division called meiosis, in which two rounds of chromosome segregation follow a single round of DNA replication. In prep...
متن کاملMeiosis: How Male Flies Do Meiosis
In meiosis in male fruitflies, chromosome pairing events do not facilitate genetic exchange, but rather create bivalents that can be sequestered to discrete pockets of the prophase nucleus. This assignment of homologs to a common pocket likely facilitates the orientation of homologous centromeres to opposite poles.
متن کاملMitosis and Meiosis
Introduction As we discussed in class, biological growth is a multi-dimensional phenomena. In essence, the basic unit of life, the cell, must duplicate itself. One "mother" cell must become two "daughter" cells, through the process of Cell Division, mostly MITOSIS. This is a completely asexual event and involves replication of the nucleus and its constituents and dividing up of the cytoplasm, t...
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ژورنال
عنوان ژورنال: Human Reproduction
سال: 2002
ISSN: 0268-1161,1460-2350
DOI: 10.1093/humrep/17.11.3006-a