Reproduction and development

TASK 1: Budding yeast

NP: suspension of yeasts

Prepare a native preparation of yeast and observe the buds on the surfaces of some of the cells.


Fig.: Budding yeast.

TASK 2: Cytological changes in vaginal mucosa during estral cycle

PP: stained vaginal swab of rat in different phases of estral cycle "proestrus, estrus, metestrus, and diestrus".

Observe and draw a specimens from four different phases of estral cycle. Each phase has its typical finding: proestrus (large epithelial cells with dark nuclei), estrus (corneous cells without nuclei), metestrus (cells with large nuclei, mucus), diestrus (mucus and leukocytes).


Fig.: Phases of estral cycle with typical findings in vaginal mucosa.

TASK 3: Cleavage of rabbit egg

PP: egg surrounded by follicular cells and egg consisting of two blastomeres; photographs of egg with two polocytes and egg consisting of eight blastomeres - "vajíčka králíka".

Observe permanent preparations and photographs.


Fig.: Rabbit egg: A – surrounded by follicular cells, B – with two polocytes, C – consisting of two blastomeres, D – consisting of eight blastomeres.

TASK 4: Ontogenic development of different animal species

PP: the insect with imperfect metamorphosis (chicken louse Menacanthus stramineus, Degeeriela rufa), flasks with developmental stages of holometabolous insect (gypsy moth Lymantria dispar), fish (common trout Salmo trutta), amphibian (common frog Rana temporaria), bird (domestic fowl Gallus gallus), mammal (brown rat Rattus norvegicus; human fetus Homo sapiens).


Fig.: Ontogenic development of different animal species: A – chicken louse Menacanthus stramineus (egg, 3 nymphs, imago), B – gypsy moth Lymantria dispar (egg, larva, pupa in cocoon, imago), C – common trout Salmo trutta (egg, embryo, hatched larva with yolk sac (=alevin), adult fish), D – common frog Rana temporaria (egg, tadpole, frog with tail, frog), E – domestic fowl Gallus gallus (egg, embryo, chicken after hatching, adult), F – brown rat Rattus norvegicus (uterus in early and late stage of gravidity, fetus and adult of rat).