Cell Division, Development - English

Atlas of 24 OHP Transparencies size 22 x 28 cm, comprising over 95 color pictures. Specially selected and beautiful multicolored photomicrographs are presented in this atlas.

Typical Cell Division in the Root Tip of the Hyacinth. An unique series to illustrate the normal sequence of mitosis. The photomicrographs show each stage in a high degree of magnification. The cell components are differentiated in contrasting colours by a special staining technique. - Interphase, the resting nucleus the chromatin, nuclear membrane and nucleoli - Early prophase, chromosomes as fine threads - Late prophase, chromosome threads shorten by contraction - Early metaphase, daughter chromosomes are formed - Metaphase, chromosomes arranged to the equatorial plate - Early anaphase, chromatids separate in daughter chromosomes - Late anaphase, daughter chromosomes reach the opposite cell poles - Early telophase, chromosomes form the daughter nuclei - Late telophase, new cell wall is formed and nucleoli are reformed - Reconstruction of interphase nuclei. Complete separation of the daughter cells. -
Development of the Microspore Mother Cells of Lilium (Anthers). New combination of hereditary traits and reduction of the number of chromosomes are the aim of meiotic division. Lilium is highly suitable because of the large size and clearness of its chromosome structures - Young anther of lily. t.s. - Microspore mother cells, resting stage - Leptotene, chromosomes appear as fine threads - Zygotene, homologous chromosomes associate in pairs - Pachytene, complete pairing - Diplotene, bivalent chromosomes split, interchange of genetic material - Diakinesis, contraction of bivalents - Metaphase of the first (heterotypic) division, formation of the equatorial plate - Equatorial plate, showing duplicated chromosomes - Metaphase, a spindle is formed - Anaphase, movement of daughter chromosomes towards the cell poles, two haploid sets of chromosomes are separated - Telophase, new cell wall is formed - Prophase of second (homeotypic) division - Metaphase of second division - Pollen tetrads. Four nuclei are formed, each bearing the haploid number of chromosomes - Uninuclear microspores after separation of daughter cells - Prophase, Metaphase, Anaphase and Telophase of the third division. - Mature two-nucleate pollen grain at the time of shedding, with tube cell and generative cell - Mature pollen grain w.m. - Growing pollen grain showing pollen tube - Growing pollen tube, l.s. showing division of generative cell into two sperm nuclei. -
Development of the Megaspore Mother Cells of Lilium (Embryosac). Meiotic and mitotic divisions also take place in the development of the female gametophyte. In order to produce this series, thousands of sections had to be prepared - Ovary of lily, t.s. for general study - Very young ovary - Developing embryosac mother cell - Megaspore mother cell, pachytene stage of prophase. - Anaphase of first (heterotypic) division. Spindle fibres - Telophase of first division. Each daughter nucleus contains the haploid number of chromosomes - Two-nucleate embryosac, prophase of the following second division - Anaphase of the second (homeotypic) division, two division figures and spindles - Telophase of the second division - Primary four-nucleate stage - Primary four-nucleate stage, three nuclei migrate to the chalazal end, one remains in the micropylar end - Prophase of third division - Metaphase of third division, after the three chalazal nuclei have fused - Telophase of third division - Second four-nucleate stage, two haploid and two triploid nuclei. - Metaphase and Anaphase of fourth division - Eight-nucleate stage, the mature embryosac. Egg nucleus, synergid, polar, and antipodal nuclei - Double fertilization by the two sperm nuclei of the pollen tube - Formation of embryo, early and later stage. Integument with young embryo and endosperm - Young embryo with suspensor cells, l.s. - Older embryo, l.s. with cotyledon. -
Maturation and Cleavage of Ascaris megalocephala bivalens. Due to its low number of chromosomes (only four), Ascaris is an ideal zoological example to demonstrate the phenomena of reduction divisions, fertilization and early cleavage in animals - Primary germ cells in growing zone of oviduct - Entrance of spermatozoon in the oocyte - Early oocyte, two tetrads, each with four chromosomes - First maturation division. Eight chromosomes visible. - First polar body - Second maturation division. Four chromosomes - Second polar body. Only two chromosomes remain in the oocyte - Mature oocyte with male and female pronuclei. Both polar bodies can be seen - The maternal and paternal chromosomes become visible (fertilization) - Metaphase of the first cleavage, equatorial plate with four chromosomes. - Metaphase, side view shows chromosomes, spindle fibres, centrioles - Anaphase, movement of the daughter chromosomes towards the poles - Early telophase, constriction of the cell body - Telophase, further division - Late telophase, complete division of the cell body - Second cleavage with two division figures - Later stage showing young embryo. - Development of the Female Gametophyte of Pinus. With many species of pine, the ovules mature within two vegetation periods. In the first year, pollination and growth of female gametophytes takes place. The formation of archegonia and fertilization takes place in following spring. - Young female cone, median l.s. - Bract scale, ovuliferous scale and ovule, l.s. - Young ovule before pollination, l.s. with megaspore mother cell - Growing ovule at free nuclear stage - Growing ovule, later stage with young macroprothallium - Mature archegonium, median l.s. showing neck canal cells, ventral canal cell, egg nucleus, jacket cells, paranuclei - Fertilization of archegonium by entrance of the pollen tube - First division of fertilized egg nucleus, anaphase - Four-nucleate stage, nuclei in the centre - Four-nucleate stage, nuclei migrate towards the base of archegonium - Sixteen-nucleate stage, the nuclei lie in four tiers of four. Rosette cells, suspensor cells, embryonic cells - Young proembryo with short suspensor cells - Older proembryo with elongated suspensor cells and four embryos - Mature embryo with endosperm, median l.s. showing cotyledons, radicle, hypocotyl, plumule - Mature embryo with endosperm, t.s. showing the eight cotyledons.

The notes are in English but the transparencies are in German.