spermatogenesis Flashcards
spermatogonia?
spermatogonia are diploid germ cells in the testes that maintain their numbers by mitosis, tus maintaining spermatozoa numbers through life.
they contain both X and Y sex chromosomes. at a certain point, a spermatogonium will stop its other duties and begin meiosis
in males meiosis occurs during spermatogenesis, in which spermatogonia in the testes become ?
spermatozoa
when does spermatogenesis occur
at puberty
what are two parts to spermatogenesis?
- spermatocytogenesis
- spermiogenesis
what is spermatogenesis
when germ cells in the seminiferous tubules become haploid spermatozoa (mature sperm)
what is spermatocytogenesis?
first stage of spermatogenesis
- spermatogonia A cells -> spermatogonia B cells - meosis I
- divide until become primary spermatocytes (diploid) (homologous recombination occurs)
- meosis II secondary spermatocytes (haploid) - spermatids (haploid)
spermiogenesis?
- rounded spermaid cell changes shape, becoming elongated and developing the familiar head and tail
what does the acrosome of sperm contain and what is its function
contains enzymes
help sperm penetrate outer layers of ovum during fertilization
where does mitochondria go in sperm
concentrated in first part of tail
when spermatids become spermatozoa do they lose their cytoplasm?
yes and the nucleus is packed into the head
what hormones are in charge of regulation of spermatogenesis?
GnRH from hypothalamus
LH and FSH from anterior pituitary
what does LH stimulate leydig intersitial cells to do?
production of testosterone
LH indirectly promotes spermatogenesis by inc intratesticular testosterone (promotes maturation of sperm)
what does FSH do?
stimulates sertoli cells to support spermatogenesis (sertoli cells are required for the progression of spermatogonia to sperm)
what do sertoli cells look like and where are they found?
found as irregular columns in shape in a simple columnar epithelium and they extend from the basement membrane to the luminal surface of the seminiferous epithelium.
recognised by their prominent nucleoli
what do Sertoli cells do?
support and nutrition of developing germ cells
compartmenalization of seminiferious tubule by tight junctions which provides a protected environment for germ cells
controlled release of mature spermatids into tubular lumen
secretion of fluid, proteins and growth factors
phagocytosis of degenerating sperm cells.
