Page 117 - Atlas of Histology with Functional Correlations

Meiosis is a special type of cell division that is restricted to male and female
germ cells. This type of division produces an ovum and a spermatozoon whose
chromosome numbers have been reduced from diploid (46 chromosomes) to
haploid (23 chromosomes).

The process of meiosis involves two successive cell divisions after one DNA

replication. This ensures that haploid cells are produced from every cell that
enters meiosis. The recombination of genes and the establishment of a full
chromosome count occur at fertilization of the ovum by the sperm, thus ensuring
viability of the progeny. Additional information concerning the meiotic process

is described in Chapters 20 and 21.

Supplemental micrographic images are available at
www.thePoint.com/Eroschenko13e under Cell and Cytoplasm.

Summary

Cells and the Cell Cycle

CELL POPULATIONS IN ADULTS

Permanent—nerve and muscle cells are not replaced when damaged
Stable cell population—liver cells can proliferate to replace removed or
damaged cells
Renewing cell population—skin, gastrointestinal organs, blood cells in red

bone marrow, and germ cells in testes are constantly replaced

CELL CYCLE: INTERPHASE AND

MITOSIS

Divided into interphase and mitosis
Interphase is prolonged and consists of different phases that replicate cell
contents

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