Seminiferous Tubules (human) Ovary (cat) Ovum (squirrel) Primordial Follicle (human) Secondary Follicle (human) Addition of Yolk to Oocyte by Follicle Cells Maturing Secondary Follicle (monkey) Secondary Ooocyte in Antral Follicle (human) Oogenesis – formation of polar bodies (rat, human, and mouse, respectively) (Click on the link to run the animation) Meiosis http://biology-web.nmsu.edu/houde/MEIOSIS.mov (Close the movie window to return to this presentation) Frog (Xenopus) Oogenesis http://biology-web.nmsu.edu/houde/frogoogenesis.mov Fertilization - Acrosome Reaction and Cortical Reaction Sea Urchin rhodamine phalloidin staining of fertilization cone (explosive actin polymerization) http://biology-web.nmsu.edu/houde/Rhphalloidinstainingfertilizationcone.mov Inositol triphosphate (IP3) is a second messenger released from phosphatidyl inositol bisphosphate (PIP) by phospholipase C, and binds to and activates a calcium channel in the endoplasmic reticulum, releasing a wave of Ca++ that spreads across the ovum. Calcium ion stimlates the release of cortical granules to the perivitelline space, which widens as a slow block to polyspermy and deactivates bindin receptors. Sea Urchin Cortical Reaction phase contrast left intracellular Ca++ right http://biology-web.nmsu.edu/houde/mk0780641001.mov Sea Urchin fusion of egg and sperm pronuclei http://biology-web.nmsu.edu/houde/Fusioneggspermpronuclei.mov Ascidean Cortical Rotation frog (Xenopus) cortical rotation (follows gravitational rotation) http://biology-web.nmsu.edu/houde/corticalrotation.mov frog (Xenopus) gravitational rotation, Cleavage http://biology-web.nmsu.edu/houde/fert2.mov Branchiostoma Cleavage and Blastulation Xenopus Blastulation frog (Xenopus) Blastulation http://biology-web.nmsu.edu/houde/xenopus embryo.mov Branchiostoma Gastrulation Xenopus Zygote Cytoplasmic Fate Map Xenopus median section blastulation – bottle cells Xenopus Vegetal and Median Gastrulation Frog (Xenopus) Gastrulation, formation of yolk plug, Neurulation http://biology-web.nmsu.edu/houde/RKellergastrulation.mov Xenopus Median and Parasagittal Gastrulation Frog (Xenopus) Gastrulation – median optical section http://biology-web.nmsu.edu/houde/froggastmedianopticalsection.mov Keller sandwich Cutout (frog) http://biology-web.nmsu.edu/houde/sandwich_cutout.mov Keller sandwich explant (chordaneural elongation) http://biology-web.nmsu.edu/houde/Kellersandwichdorsallipexplant.mov Branchiostoma Neurulation Xenopus Neurulation