Talk:Spermatozoa Development

Dimensions of human ejaculated spermatozoa in Papanicolaou-stained seminal and swim-up smears obtained from the Integrated Semen Analysis System (ISAS(®))

Asian J Androl. 2010 Sep 20. [Epub ahead of print]

Bellastella G, Cooper TG, Battaglia M, Ströse A, Torres I, Hellenkemper B, Soler C, Sinisi AA.

[1] Centre of Reproductive Medicine and Andrology of the University, Münster D-48149, Germany [2] Department of Clinical and Experimental Medicine and Surgery, Endocrinology and Medical Andrology Section, Seconda Universita`di Napoli, Napoli 80131, Italy.

Objective measurements are required for computer-aided sperm morphometric analysis (CASMA) machines to distinguish normal from abnormal sperm heads. The morphometric characteristics of spermatozoa in 72 samples of semen and of spermatozoa from 72 other semen samples after swim-up were quantified by the semi-automated Integrated Sperm Analysis System (ISAS) computer-aided system, which measured the sperm head parameters length (L), width (W), area (A), perimeter (P), acrosomal area (Ac), and the derived values L/W and P/A. For each man a homogeneous population of distributions characterized seminal spermatozoa (7 942 cells: median values L 4.4 μm, W 2.8 μm, A 9.8 μm(2), P 12.5 μm, Ac 47.5%, L/W 1.57, P/A 1.27), and there was no significant difference in within- and among-individual variation. Different men could have spermatozoa of significantly different dimensions. Head dimensions for swim-up spermatozoa from different men (4 812 cells) were similar to those in semen, differing only by 2%-5%. The values of L, W and L/W fell within the limits given by the World Health Organization (WHO). Although these samples were not biologically matched, linear mixed-effects statistical analyses permitted valid comparison of the groups. A subpopulation of 404 spermatozoa considered to fit the stringent criteria of WHO 'normal' seminal spermatozoa from both semen and swim-up were characterized by median values (and 95% confidence intervals) of L, 4.3 μm (3.8-4.9), W, 2.9 μm (2.6-3.3), A, 10.2 μm(2) (8.5-12.2), P, 12.4 μm (11.3-13.9), Ac, 49% (36-60), L/W, 1.49 (1.32-1.67) and P/A, 1.22 (1.11-1.35). These median values fall within the 95th centile confidence limits given by WHO, but the confidence intervals for L and W were larger. Although these differences in head dimensions among men and after swim-up could be detected by CASMA, the small differences make it unlikely that technicians would be able to distinguish them. The values could be used as default sperm head values for the CASMA machine used here.

PMID: 20852650

Microgravity promotes differentiation and meiotic entry of postnatal mouse male germ cells

Pellegrini M, Di Siena S, Claps G, Di Cesare S, Dolci S, Rossi P, Geremia R, Grimaldi P. PLoS One. 2010 Feb 4;5(2):e9064. PMID: 20140225 | PLoS One

"A critical step of spermatogenesis is the entry of mitotic spermatogonia into meiosis. Progresses on these topics are hampered by the lack of an in vitro culture system allowing mouse spermatogonia differentiation and entry into meiosis. Previous studies have shown that mouse pachytene spermatocytes cultured in simulated microgravity (SM) undergo a spontaneous meiotic progression. Here we report that mouse mitotic spermatogonia cultured under SM with a rotary cell culture system (RCCS) enter into meiosis in the absence of any added exogenous factor or contact with somatic cells."

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2847216/?tool=pubmed

A comparative view of sperm ultrastructure

Fawcett DW. Biol Reprod. 1970 Jun;2:Suppl 2:90-127. PMID: 5521054

http://www.biolreprod.org/content/2/Supplement_2/90.long

Spermatogenesis-Specific Features of the Meiotic Program in Caenorhabditis elegans

(excellent meiosis images) http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2720455/?tool=pmcentrez

All You Wanted to Know About Spermatogonia but Were Afraid to Ask

http://www.andrologyjournal.org/cgi/reprint/21/6/776

"During mammalian spermiogenesis, histones at the onset of the differentiation process are gradually replaced by transition proteins and protamines (14,22) and although the replacement is almost complete in most species, in humans ~15% of the mature sperm chromatin remains associated with histone variants"

Sequence-specific packaging of DNA in human sperm chromatin

http://www.ncbi.nlm.nih.gov/pubmed/3576213

"The DNA in human sperm chromatin is packaged into nucleoprotamine (approximately 85%) and nucleohistone (approximately 15%). Whether these two chromatin fractions are sequence-specific subsets of the spermatozoon genome is the question addressed in this report. Sequence-specific packaging would suggest distinct structural and functional roles for the nucleohistone and nucleoprotamine in late spermatogenesis or early development or both. After removal of histones with 0.65M NaCl, exposed DNA was cleaved with Bam HI restriction endonuclease and separated by centrifugation from insoluble nucleoprotamine. The DNA sequence distribution of nucleohistone DNA in the supernatant and nucleoprotamine DNA in the pellet was compared by cloning size-selected single-copy sequences and by using the derived clones as probes of nucleohistone DNA and nucleoprotamine DNA. Two clones derived from nucleohistone DNA preferentially hybridized to nucleohistone DNA, and two clones derived from nucleoprotamine DNA preferentially hybridized to nucleoprotamine DNA, which demonstrated the existence of sequence-specific nucleohistone and nucleoprotamine components within the human spermatozoon."