Biology 4.1 - Spermatogenesis and Oogenesis.

Spermatogenesis

• Spermatogenesis is the formation of spermatozoa in the seminiferous tubules of the testes.

• Germinal epithelium cells (diploid) divide by mitosis to form diploid spermatogonia and more germinal epithelium cells. 
• The spermatogonia also undergo mitosis to form diploid primary spermatocytes and more spermatogonia. 
• The primary spermatocytes undergo meiosis I to form haploid secondary spermatocytes. 
• The haploid secondary spermatocytes undergo meiosis II to form haploid spermatids. 
• The spermatids mature to form spermatozoa. 
• The Sertoli cells protect and nourish the spermatozoa. 
• The Leydig (interstitial) cells secrete testosterone, which is involved in stimulating the process of spermatogenesis

Oogenesis 

• Oogenesis is the production of a secondary oocyte in the ovary.

PART 1 - BEFORE BIRTH

• Diploid germinal epithelium cells divide by mitosis to produce diploid oogonia, and more germinal epithelium cells. 
• The oogonia divide repeatedly by mitosis to form diploid primary oocytes, and more…