Talk:2010 BGD Practical 3 - Gametogenesis

Spermatazoa Statistics

The following data is based normal human male values for reproductive ages between 20 to 50 years:

45 to 207 million spermatozoa produced per day within the two testes
2,000 spermatozoa approx per second each day
Compare this to adult human red blood cell production of about 250,000 million RBCs per day
182 million spermatozoa stored (epididymal reserves) up to per epididymis
440 million spermatozoa extragonadal stored
225 million extragonadal spermatozoa in the ductuli deferentia and caudae epididymides per ejaculation
23 million spermatozoa approx (all animals) per gram testicular parenchyma per day

(Data: Amann RP, Howards SS., 1980 and Gordon-Smith EC., 2007)

Female Oogenesis

Meiosis initiated once in a finite population of cells

1 gamete produced / meiosis

Completion of meiosis delayed for months or years

Meiosis arrested at 1st meiotic prophase and reinitiated in a smaller population of cells

Differentiation of gamete occurs while diploid (in first meiotic prophase)

All chromosomes exhibit equivalent transcription and recombination during meiotic prophase

Male Spermatogenesis

Meiosis initiated continuously in a mitotically dividing stem cell population

4 gametes produced / meiosis

Meiosis completed in days or weeks

Meiosis and differentiation proceed continuously without cell cycle arrest

Differentiation of gamete occurs while haploid (after meiosis ends)

Sex chromosomes excluded from recombination and transcription during first meiotic prophase

NCBI Bookshelf - Endocrinology: An Integrated Approach. Nussey, S.S. and Whitehead, S.A. Oxford, UK: BIOS Scientific Publishers, Ltd; 2001. The ovary - folliculogenesis and oogenesis | Spermatogenesis

Mitosis and Meiosis: MBoC Fig 20-6

Oogenesis: MBoC ch20f16.gif

Spermatogenesis: Dev Biol Ch19f18.jpg

Seminiferous Tubule: Dev Biol ch19f17.jpg