Introduction to male embryology and spermatogenesis Flashcards
what do supporting cells in males which are derived from the surface epithelium of the testis become and what happens at the same time
sustentacular cells, or Sertoli cells.
At about the same time, PGCs give rise to spermatogonial stem cells
what happens to the sex cords in males shortly after puberty
they acquire a lumen and become the seminiferous tubules
At regular intervals, cells emerge from this stem cell population to form ____________
typeA spermatogonia and their production marks the initiation of spermatogenesis
The last cell division produces type B spermatogonia which ______________
divide to form primary spermatocytes
describe formation of spermatids.
Primary spermatocytes then enter a prolonged prophase (22 days) followed by rapid completion of meiosis I and formation of secondary spermatocytes. During the second meiotic division, these cells immediately begin to form haploid spermatids
from the time type A cells leave the stem cell population to formation of spermatids why is cytokinesis incomplete
so that successive cell generations are joined by cytoplasmic bridges
________________________ remain embedded in deep recesses of Sertoli cells throughout their development.
spermatogonia and spermatids
what is the function of the sertoli cells
support and protect the germ cells, participate in their nutrition, and assist in the release of mature spermatozoa
how does LH work
it binds to receptors on Leydig cells and stimulates testosterone production, which in turn binds to Sertoli cells to promote spermatogenesis
what is the function of FSH
binds to Sertoli cells and stimulates testicular fluid production and synthesis of intracellular androgen receptor proteins.
what changes occur during spermiogenesis
- formation of the acrosome
- condensation of the nucleus
- formation of neck, middle piece, and tail
- shedding of most of the cytoplasm
what phagocytize residual bodies
sertoli cells
where do spermatozoa go after being fully formed
enters the lumen of seminiferous tubules, pushed towards the epididymis by contractile wall of seminiferous tubules.
where do spermatozoa gain full motility
in the epididymis
what are he most common chromosomal abnormalities in abortuses?
45, X (turner syndrome), triploidy and trisomy 16
what is down syndrome caused by
extra copy of chromosome 21 (trisomy 21)
what causes patau syndrome
trisomy 3
what causes Klinefelter syndrome
The cells have 47 chromosomes with a sex chromosomal complement of the XXY type and a sex chromatin (Barr) body is found in 80 % of cases
what causes Turner’s Syndrome
45, X karyotype
what causes cri-du-chat syndrome
caused by partial deletion of short arm of chromosome 5
what causes Angelman’s Syndrome
Microdeletion occurs on the long arm of chromosome 15 (15q11-15q13).
what causes Prader-Willi Syndrome
micro-deletion occurs on the paternal chromosome
what causes DiGeorge Syndrome
deletion in 22q11
what is used to assess chromosome number and integrity and what is its requirement
Cytogenetic analysis requiring it in only dividing cells
what does FISH (Fluorescence in situ hybridization) use
specific DNA probes to identify ploidy for a few selected chromosomes and for detecting microdeletions bu hybridizing chromosomes
what do micro-arrays use
use spots of specific DNA sequences (probes) attached to a solid surface, usually glass or silicon.
what can micro-arrays detect
Results can detect single nucleotide polymorphisms, mutations and changes in expression levels
