Page 673 - First Aid for the USMLE Step 1 2020, Thirtieth edition [MedicalBooksVN.com]_Neat
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RepRoductive ` REPRODUCTIVE—ANATOmy RepRoductive ` REPRODUCTIVE—PHySIOlOgy SectioN iii 629
` REPRODUCTIVE—PHySIOlOgy
Spermatogenesis Begins at puberty with spermatogonia. Full “Gonium” is going to be a sperm; “Zoon” is
development takes 2 months. Occurs in “Zooming” to egg.
seminiferous tubules. Produces spermatids Tail mobility impaired in ciliary dyskinesia/
that undergo spermiogenesis (loss of Kartagener syndrome infertility.
cytoplasmic contents, gain of acrosomal cap) Tail mobility normal in cystic fibrosis (in CF,
to form mature spermatozoa. absent vas deferens infertility).
Spermiogenesis
Spermatogonium 1° spermatocyte 2° spermatocyte Spermatid Mature spermatozoon
Diploid Diploid Haploid Haploid Haploid
(2N, 2C) (2N, 4C) (1N, 2C) (1N, 1C) (1N, 1C)
Sperm
23 Acrosome Tail
single
23 (sex= X) Head
sister Nucleus
Blood-testis chromatids
barrier (sex= X-X) 23 Neck
single
46 46 (sex= X) Middle
single sister piece
chromo- Tight junction chromatids
somes ( X-X )
sex=
(sex= X-Y) Y-Y 23
single
23 (sex= Y)
sister N = ploidy
chromatids C = # of chromatids
(sex= Y-Y) 23
single
Replication
(interphase) Meiosis I Meiosis II (sex= Y)
FAS1_2019_15-Repro.indd 629 11/7/19 5:52 PM
