Mitosis and Meiosis

Onion (Allium) Root Tip

Location of Mitotic Cells on Root Tip Root cap Observe cells in the region just above the root cap

Stages of Mitosis in Onion Root Tip

Whitefish Blastula Mitotic stages

Grasshopper Testis

Spermatogenesis: Grasshopper Testes Spermatogonia (not yet in meiosis)

Primary Spermatocyte in Meiosis I: 2n chromosomes, tetrads Secondary Spermatocyte in Meiosis II, 1n chromosome, dyads

Grasshopper Testis

Spermatids, 1n

Mature Spermatozoa, 1n

Mammalian Testes: Slide #10 p. 3 diagram Seminiferous tubules: tightly coiled tubules (~ 500 m) where millions of sperm are produced. Epididymis: sperm travels and matures in a 1-3 week journey.

Interstitial space: Leydig cells  Testosterone

Interstitial space: Leydig cells  Testosterone

P. 4 diagram Ascaris Oviduct & Uterus Sperm Penetration Notice: Sperm head (haploid) have entered the eggs. Meiosis in the egg can only resume after sperm penetration. Note the lack of extensive membranes which will be seen to surround the egg later.

Ascaris

Ascaris

Ascaris