3: Gametogenesis and Hormones in Reproduction and Development
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development of gametes
Gametogenesis
Gametogenesis usually not completed until the organism has become
physically mature
Gametogenesis completed in the sexually mature adult, begins at _ times during development, depending on the species
different
Gametogenesis divided into four phases
a.) the extraembryonic origin of the germ cells and their migration into the gonads, b.) an increase in the number of germ cells by mitosis, c.) a reduction in chromosomal number by meiosis, and d.) structural and functional maturation of the eggs and spermatozoa
The first phase of gametogenesis is _ in males and females, whereas distinct differences exist between the male and female patterns in the last three phases.
identical
process of sperm cell production
Spermatogenesis
Spermatogenesis _ process in the adult male
prolific and continuous
Spermatogenesis occurs in the paired male gonads, or testes, specifically in the _
seminiferous tubules
each ejaculation of a human male contains _ sperm cells, and males can ejaculate daily with little loss of fertilizing capacity
100 to 650 million
Primordial germ cells of the embryonic testes differentiate into
spermatogonia
diploid cells that are the precursors of sperm
spermatogonia
are undifferentiated cells located near the outer wall of the seminiferous tubules
Spermatogonia
Spermatogonia undergo repeated _ to produce more spermatogonia.
mitosis
In a mature male, about 3 million spermatogonia per day differentiate into _
primary spermatocytes.
diploid or haploid? Each primary spermatocyte undergoes first meiotic division producing _
haploid secondary spermatocytes.
how many are they? In the second meiotic division, each secondary spermatocyte gives rise to _
two haploid spermatids.
_ are produced from the original primary spermatocyte.
Four spermatids
Spermatids then differentiate into a mature sperm cell or _.
spermatozoa
The differentiation of the spermatids into sperm cells is called _
spermiogenesis
corresponds to the final part of spermatogenesis and comprises the following individual processes that partially proceed at the same time.
spermiogenesis
Spermatogenesis involves association of the developing sperm with _ which transfer nutrients to the spermatozoa
large Sertoli cells
The release of a sperm cell from its connection to a Sertoli cell is known as .
spermiation
During spermatogenesis, the developing sperm are gradually pushed toward the _, flow toward _ and make their way to the _ where they acquire motility.
center or lumen of seminiferous tubules ducts of the testes epididymis
This process from spermatogonia to motile sperm, takes _ in the human male to complete.
64 days