Inbreeding and outbreeding : their genetic and sociological significance / by Edward M. East ... and Donald F. Jones ... 46 illustrations.

  • East, Edward M. (Edward Murray), 1879-1938.
Date:
[1919], ©1919
Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Inbreeding and outbreeding : their genetic and sociological significance / by Edward M. East ... and Donald F. Jones ... 46 illustrations. Source: Wellcome Collection.

    42/320 (page 38)
    38 INBREEDING AND OUTBREEDING are similar in all essential features, as may be seen in Fig. 9, the elimination of three out of four of the oocytes taking spermatogenesis Spermato- Éor.Ia OOGENílSIS I Multiplication . period i (4V vk tY) Oogenia 1 V 6ro«th period 1 / •. „ Primary , Spermatocyte lik 1 Pairing of Chr-oTsosomes J ! \ j- Keducing division Secondary ■•ermato- cytes ■•J'y l/^ sperm|to- yc-o !f!Sr 0 (t Sperw- ie\ atozoa Primary oocyte Secondary oocyte {ovüm ana f irst polar body) Maturo ovum and polar bodies Mature ovum Zv¿ote of férti]}zea ovum with full number of chromosomes restored Fig. 9.—Diagram of gametogenesis showing the parallel between maturation of the eperm cell and maturation of the ovum. (After Guyer.) place in order that their store of nutritive materials may go to make one large egg. Fertilization consists in the fusion of one egg with one sperm, thus bringing back the double number of chromo-