BIO1140 Introduction to Cell Biology BIO1140 Lab 5 Meiosis BIO1140 Introduction to Cell Biology

BIO1140 Introduction to Cell Biology Objectives Identify selected meiotic phases and their characteristics Microsporogenesis in Lilium Meiosis in Ascaris. Identify various stages during micro-sporogenesis. Study spermatogenesis in the rat testis and oogenesis in the rabbit ovary. Capture digital images of assigned material and draw a biological drawing based on those photos. BIO1140 Introduction to Cell Biology

Separation of homologous  chromosomes Separation of chromatids Meiosis Reductive division of cells Diploid cell (2n) Pre-mieotic interphase Duplication of chromosomes tetraploid cell (4n) Separation of homologous  chromosomes First division (2n) Separation of chromatids Second division haploid cells (n)

BIO1140 Introduction to Cell Biology I- Meiosis in plants Lily microsporogenesis Formation of male gametes (pollen) in Anther Identify stages and structures using prepared slides visit also website: http://www.iasprr.org/old/iasprr-pix/lily/male.shtml BIO1140 Introduction to Cell Biology

pa f Meiosis in plants anther pc e tapetum Meiosis in Lillium anther (early prophase): e: epidermis; f: filament; pa: parenchyme; pc: pollen cell precursor (prophase) pollen sacs (microsporangia)

BIO1140 Introduction to Cell Biology II- Meiosis in Animals Meiosis in Ascaris BIO1140 Introduction to Cell Biology

BIO1140 Introduction to Cell Biology Selected stages Sperm entrance Primary oocyte arrested in prophase 1 (no shell) Penetration of the spermatozoid (sp) triggers the egg nucleus (n) to continue meiosis sp n BIO1140 Introduction to Cell Biology

BIO1140 Introduction to Cell Biology Selected stages Metaphase I Presence of shell (s) Chromosomes lined up at equator (c) No polar body Male pronucleus visible (p) at center of cell p s c BIO1140 Introduction to Cell Biology

BIO1140 Introduction to Cell Biology Selected stages Anaphase I Homologous chromosomes separate and are moving to opposite spindle poles BIO1140 Introduction to Cell Biology

BIO1140 Introduction to Cell Biology Selected stages Metaphase II Similar to metaphase I but with the presence of a polar body (pb) in the perivitelline space (ps) pb ps BIO1140 Introduction to Cell Biology

BIO1140 Introduction to Cell Biology Selected stages Anaphase II Centromeres split chromatids separate then move to cell poles BIO1140 Introduction to Cell Biology

BIO1140 Introduction to Cell Biology Selected stages Interphase Following telophase II, haploid male and female pronuclei (pn) in interphase prior to fusion (fertilization). Second polar body expelled (not visible here) The resulting zygote (2n) continues to divide by mitosis. pn BIO1140 Introduction to Cell Biology

BIO1140 Introduction to Cell Biology Selected stages Mitotic cleavage of the embryo Stop after this slide BIO1140 Introduction to Cell Biology

BIO1140 Introduction to Cell Biology Meiosis in mammals Gametogenesis in rat testis and rabbit ovary You’ll be assigned one species for your lab report Observe both species (exam material) Resume talk here BIO1140 Introduction to Cell Biology

Rat (Rattus norvegicus) spermatogenesis Occurs within the walls of the seminiferous tubules Recognize stages by position (immature stages near outside of tubule, mature stages near lumen). See http://www.ouhsc.edu/histology/ for details You should follow the link and show students the main structures seen on testis CS – Or use next slide BIO1140 Introduction to Cell Biology

BIO1140 Introduction to Cell Biology sc bl ps st sg ss sp L bl: basal lamina, L: lumen of the tubule, sc: sertoli cell nucleus, sg: spermatogonia, ps: primary spermatocyte, ss: secondary spermatocyte, sp: sperm cells (cross section), st: spermatids BIO1140 Introduction to Cell Biology

Rabbit (Sylvilagus floridanus) oogenesis Identify maturation stages of the follicles depending on position in the ovary, number of layers of follicular cells and presence of fluid-filled cavities See http://www.ouhsc.edu/histology for details BIO1140 Introduction to Cell Biology

BIO1140 Introduction to Cell Biology Primordial follicle Primordial follicle (pf) are located underneath the ovary epithelium (ep) Surrounded by one layer of squamous (=flat) follicular cells ic: interstitial cells pf ic ep BIO1140 Introduction to Cell Biology

Primary unilaminar follicle Located deeper in the ovary Surrounded by one layer of cuboidal follicular cells (fc) Contains a primary oocyte (po) n: oocyte pronucleus po n fc BIO1140 Introduction to Cell Biology

Growing follicle (primary multilaminar): Slightly deeper in the ovary Surrounded by several layers of follicular cells (fc) Contain primary oocyte (dash lines). n: oocyte pronucleus fc n BIO1140 Introduction to Cell Biology

Mature or Graafian Follicle Largest follicle Many layers of follicular cells (fc) One big or several fluid-filled cavities (fca) Contains secondary oocyte (so) stopped in metaphase II = mature oocyte Comes near to ovarian epithelium prior to ovulation so fca fc BIO1140 Introduction to Cell Biology

BIO1140 Introduction to Cell Biology Lab5 Report: 3 pages Page 1: Title page Page 2: Annotated picture printout Page 3: Biological drawing You must take 2 pictures during the lab that you will use for your lab report: Report instructions BIO1140 Introduction to Cell Biology

Rabbit ovary (Sylvilagus floridanus) Picture 1: Global view at 10x showing follicles at various stages (at least 2 stages, such as primordial and unilaminar) plus (if possible) ovarian epithelium. Picture 2: close-up view at 40x of picture 1 showing a unilaminar or multilaminar follicle. (picture 2 must be a subset of picture 1, taken at 40x) BIO1140 Introduction to Cell Biology

Rat testis (Rattus norvegicus) Picture 1 : Global view at 10x of a cross section showing several seminiferous tubules. Picture 2: magnified view at 40x of picture 1 showing both the lumen and the periphery of one seminiferous tubule. (picture 2 must be a subset of picture 1, taken at 40x) BIO1140 Introduction to Cell Biology

BIO1140 Introduction to Cell Biology Lab5 Report Annotated picture (picture 1): use template file (download on lab website) to print picture (grayscale), then label either on computer or by hand. Biological drawing (picture 2): read instructions in lab manual appendix. Remember: no shading, stippling, patterns, all lines have same thickness. Follow biological drawing instructions relative to labels and caption for both pages BIO1140 Introduction to Cell Biology

BIO1140 Introduction to Cell Biology Lab5 Report Take pictures showing the required view and structures then call one of your TAs so they can check the content of your pictures and evaluate their quality Do not leave without saving (and/or emailing) the pictures or you won’t have any material for your assignment (penalty will apply) Add a scale bar AND a caption to both the printout and the drawing pages BIO1140 Introduction to Cell Biology

Lab 5 Report and evaluation Available documents (lab manual and/or Lab web): List of structures you can observe on sections - use this list to label your drawing. Instruction file for lab5 and biological drawing. Guide Biolabo: labeling, scale bar and caption sections of the “Biological drawings” chapter. Don’t forget: Tech skill marks: 15% of lab5 mark (cleanliness, microscope use and quality of pictures taken). BIO1140 Introduction to Cell Biology

Corrected lab5 reports and Final lab marks Corrected lab5 reports will be available to pick up about 3 weeks after your lab (date and location will be announced on website). All lab marks (including the final mark) will be posted on the lab website (soon). Corrector office hours are posted on the contact page of website. If the corrector for your section is not listed, contact your TA. BIO1140 Introduction to Cell Biology

FINAL EXAM: SATURDAY APRIL 11th 1PM-2:30PM Contact coordinator today if you have a conflict with another course or exam. Exam rooms: see final exam page of website Materiel covered: all Lab manual content (including appendices), lab experiments, specimens (including Lab5 structure list) and lab reports. Format: multiple choice, short answers and identification of structures on pictures. similar to prelab quizzes. BIO1140 Introduction to Cell Biology