Reproduction and Embryology course

Course on Reproduction and Embryology for medical studies.

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Gametes, gametogenesis and spermatogenesis

Essential Concepts

• Gametes are haploid reproductive cells with 23 chromosomes.
• Mature gametes only form at puberty.
• They originate from germ cells that appear in the 3rd week of development / 21st day
• Meiosis consists of 2 successive specific cell divisions
  • Meiosis I:
    • consists of the segregation of homologous chromosomes into 2 daughter cells
  • Meiosis II:
    • consists of the segregation of sister chromatids in each daughter cell
  • Genetic recombination (crossing-over) occurs during the first meiotic division
  • Non-disjunction anomalies lead to monosomies and trisomies, including sex chromosome syndromes (that should be known).
  • Meiosis is fixed and continuous in males, but discontinuous and incomplete in females.
• Spermatogenesis:
  • Spermatogenesis can only occur correctly if the testicles descend into the scrotal position early during fetal life (between the 7th and 9th month).
  • The testicle plays both an endocrine and exocrine role.
  • Spermatogenesis occurs in the seminiferous tubules.
  • Sertoli cells play a major role in spermatogenesis. Know the characteristics of Sertoli cells and their role.
  • The seminiferous tubules are divided into two compartments in which different germ cells are found.
  • Between the seminiferous tubules is located the interstitial tissue where Leydig cells are found, which produce testosterone.
  • The blood-testis barrier (barrière homéotesticulaire) (know its constitution) plays an immune role (know the different roles).