File:Morgan 1925 fig34.jpg

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Fig, 34. Diagram illustrating the two maturation divisions of the germ cells in the male

In a the chromosomes appear as thin threads (leptotene stage). These conjugate in pairs, b, beginning at the two ends of each loop.

The threads contract, and a spindle appears, d, near the nucleus. The conjugating chromosomes enter the spindle, d. There they separate, e, moving to opposite poles of the spindle. The cell protoplasm begins to constrict, f.

The chromosomes may without entering upon a resting nuclear stage pass onto a new spindle that has developed by the division of each of the centrosomes of each daughter cell, g. Each chromosome now splits throughout its length (equational division) ; half of each goes to one or the other pole. The two daughter cells then divide, giving four cells, each of which differentiates into a spermatozoon.


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Reference

Morgan, T. H. (1925). Evolution and genetics. Princeton: Princeton University Press.


Cite this page: Hill, M.A. (2024, April 20) Embryology Morgan 1925 fig34.jpg. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/File:Morgan_1925_fig34.jpg

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