Gametes & HPG Flashcards
What’s spermiogenesis?
Maturation of spermatids into fully differentiated spermatozoa
What morphological changes occur from spermatids to spermatozoa?
Formation of a head containing the nucleus
Formation of acrosome from the golgi apparatus
Formation of a tail from a single centriole
Loss of excess cytoplasm
What are gametes?
Sperm/ova
Specialised sex cells that allow us to pass our genes on to the next generation
What’s the difference between haploid and diploid cells?
Haploid = 23 individual chromosomes Diploid = 23 chromosome pairs
What type of cell forms from fusion of sperm and ovum?
Diploid cell that divides to form an embryo
What’s gametogenesis and what week?
Production of gametes
Germ cells migrate to gonads at about 6 weeks development
Germ cells colonise gonad Proliferate by mitosis Reshuffle genetic material Reduce to haploid by meiosis Mature into sperm/ova
How does mitosis/meiosis relate to spermatogenesis?
Spermatogonia divide by mitosis to form primary spermatocytes at the beginning of puberty
Meiosis I forms two haploid cells from the primary spermatocytes = secondary spermatocytes
Meiosis II forms 4 haploid spermatids per primary spermatocyte
What’s the role of the acrosome on spermatozoa?
Cap surrounding the head that contains digestive enzymes to break down the zona pellucida (glycoprotein layer) surrounding the ovum
What are spermatogenic waves?
Sperm are produced continuously to exploit time limitations of female fertility
Spermatogenesis occurs in sequential waves along the length of the seminiferous tubules
Outline oogenesis
Female germ cells colonise cortex of the ovaries
Proliferate by mitosis forming oogonia
Meiosis produces a diploid primary oocyte
Meiosis I produces 1 haploid secondary oocyte and the first polar body
Meiosis II produces a mature haploid ovum and the second polar body
What 3 things does successful reproduction require?
Fertilisation
System of support for the conceptus, embryo and finally foetus in the female
Birth at the right time
What reproductive hormone does the hypothalamus secrete?
Gonadotrophin Releasing Hormone -> anterior pituitary
What 6 peptide hormones does the anterior pituitary gland produce?
Growth hormone Adrenocorticotrophic hormone (ACTH) Thyroid stimulating hormone (TSH) Follicle stimulating hormone (FSH) Luteinising hormone (LH) Prolactin
What hormone is produced from what part of the pituitary gland for labour and lactation?
Oxytocin released form posterior pituitary gland
How is gonadotrophin releasing hormone controlled/released?
Produced in hypothalamus and pulsatile release along pituitary stalk every 1-2 hours
It’s a decapeptide hormone produced by cleavage of Pre-Pro-GnRH = acts on specific membrane receptors for intracellular signal transduction via second messengers
