BIO1140 Lab 5 Meiosis BIO1140 Introduction to Cell Biology.

BIO1140 Lab 5 Meiosis

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.


MeiosisReductive division of cells

Diploid cell (2n)

Pre-mieotic interphaseDuplication of chromosomes

tetraploid cell (4n)

First division (2n)

Second division haploid cells (n)

Separation of homologous chromosomes

Separation of chromatids

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

http://www.iasprr.org/old/iasprr-pix/lily/male.shtml

tapetum

pollen sacs (microsporangia)

e

e: epidermis; f: filament; pa: parenchyme; pc: pollen cell precursor (prophase)

pc

f

pa

Meiosis in Lillium anther (early prophase):

anther

Meiosis in plants

II- Meiosis in Animals


Meiosis in Ascaris

Selected stages


Sperm entrancePrimary oocyte arrested in prophase 1 (no shell)Penetration of the spermatozoid (sp) triggers the egg nucleus (n) to continue meiosis

sp

n

Selected stages


Metaphase IPresence of shell (s)Chromosomes lined up at equator (c)No polar bodyMale pronucleus visible (p) at center of cell

s c

p

Selected stages


Anaphase IHomologous chromosomes separate and are moving to opposite spindle poles

Selected stages


Metaphase IISimilar to metaphase I but with the presence of a polar body (pb) in the perivitelline space (ps)

pb

ps

Selected stages


Anaphase IICentromeres splitchromatids separate then move to cell poles

Selected stages


InterphaseFollowing 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

Selected stages


Mitotic cleavage of the embryo

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)


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


http://www.ouhsc.edu/histology/




sc

sg

ps

ss

st

L

bl

sp

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

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


http://www.ouhsc.edu/histology

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

ep

ic

Primary unilaminar follicle


Located deeper in the ovarySurrounded by one layer of cuboidal follicular cells (fc)Contains a primary oocyte (po)n: oocyte pronucleus

fcfc

po

n

Growing follicle (primary multilaminar):


Slightly deeper in the ovarySurrounded by several layers of follicular cells (fc)Contain primary oocyte (dash lines).n: oocyte pronucleus

nfc

Mature or Graafian Follicle


Largest follicleMany layers of follicular cells (fc)One big or several fluid-filled cavities (fca)Contains secondary oocyte (so) stopped in metaphase II = mature oocyteComes near to ovarian epithelium prior to ovulation

so

fcafc

Lab5 Report: 3 pages


Page 1: Title pagePage 2: Annotated picture printoutPage 3: Biological drawing

You must take 2 pictures during the lab that you will use for your lab report:

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)


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)


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


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


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).


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.



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 Lab 5 Meiosis BIO1140 Introduction to Cell Biology.

Documents

Transcript of BIO1140 Lab 5 Meiosis BIO1140 Introduction to Cell Biology.