Search results
Results From The WOW.Com Content Network
Spermatogenesis is the process by which haploid spermatozoa develop from germ cells in the seminiferous tubules of the testicle. This process starts with the mitotic division of the stem cells located close to the basement membrane of the tubules. [ 1 ]
The sperm genome is unable to undergo transcription during spermiogenesis, impeding its ability to respond to new challenges, such as DNA damage. [ 5 ] Associated with proper genome packaging to create mature germ cells there is a transition from histone protein binding to protamine protein binding and this transition is associated with ...
Spermatogonial stem cells are the precursors to spermatozoa, which are produced through a series of differentiation steps. [4] This is the alternative SSC outcome to self-renewal. SSCs survive within microenvironments, termed niches, which provide extrinsic stimuli that drive stem cell differentiation or self-renewal. [ 24 ]
During mouse spermatogenesis, the mutation frequencies of cells at the different stages, including pachytene spermatocytes, are 5 to 10-fold lower than the mutation frequencies in somatic cells. [11] Because of their elevated DNA repair capability, spermatocytes likely play a central role in the maintenance of these lower mutation rates, and ...
Spermatogenesis occurs in the germinal epithelium of the seminiferous tubules. Spermatogonia undergo meiosis to produce spermatids that later mature into spermatozoa. The spermatogonia duplicate their DNA to obtain 46 chromosomes in preparation for the primary division. At this stage, the germ cells are now referred to as primary spermatocytes. [3]
Acrosome reaction on a sea urchin cell. For fertilization to happen between a sperm and egg cell, a sperm must first fuse with the plasma membrane and then penetrate the female egg cell to fertilize it.
Also apoptosis decreases with age suggesting that the increase in damaged DNA of sperm as men age occurs partly as a result of less efficient cell selection (apoptosis) operating during or after spermatogenesis. [18] DNA damages present in sperm cells in the period after meiosis but before fertilization may be repaired in the fertilized egg ...
The stem cells involved are called spermatogonia and are a specific type of stem cell known as gametogonia. Three functionally separate spermatogonia cell types are recognized on the basis of the appearance of the nuclei : type A dark spermatogonia (Ad), type A pale spermatogonia (Ap), and type B spermatogonia (B).