Reproductive physiology Flashcards
What are the regulatory hormones of the male reproductive system, and where are they secreted from?
Gonadotrophin releasing hormone (GnRH)- hypothalamus
Luteinising hormone (LH)- anterior pituitary
Follicle stimulating hormone (FSH)- anterior pituitary
Testosterone (T)- testis
What are the stages in spermatogenesis?
Primordial germ cell converted to spermatogonium in seminiferous tubules
Mitotic division
Primary spermatocyte
Meiotic division I
Secondary spermatocyte
Meiotic division II
Spermatids
Mature sperm
Discuss male reproductive function.
Starts at puberty
Functions continually
Normally continues throughout the rest of life
Sperm quantity and quality generally decreases with increasing age
LH stimulates testosterone production
FSH and testosterone sustain Sertoli cell function
Sertoli cells support spermatogenesis
Discuss female reproductive function.
Starts at puberty
Functions cyclically
Normally operates until ~45 years of age
Egg quality generally decreases with increasing age
FSH stimulates (some) development of ovarian follicles and 17-beta-oestradiol synthesis
LH stimulates progesterone production
The steroids regulate uterine endometrium
Describe the HPO axis in the follicular phase.
Hypothalamus secretes GnRH which stimulates the anterior pituitary to secrete FSH and LH.
FSH and LH stimulate the ovaries to produce oestradiol.
Oestradiol has a negative feedback effect on the anterior pituitary and the hypothalamus.
Describe the HPO axis mid-cycle.
Hypothalamus secretes GnRH which stimulates the anterior pituitary to secrete FSH and LH.
FSH and LH stimulate the ovaries to produce oestradiol.
Rapid peak of LH and FSH = ovulation.
Oestradiol has a positive feedback effect on the anterior pituitary and the hypothalamus.
Describe the HPO axis in the luteal phase.
Hypothalamus secretes GnRH which stimulates the anterior pituitary to secrete FSH and LH.
FSH and LH stimulate the ovaries to produce progesterone.
Oestradiol has a negative feedback effect on the anterior pituitary and the hypothalamus.
What are the stages in oogenesis?
Primordial germ cell
Oogonium
Primary oocyte
Secondary oocyte and first polar body
Ovum and second polar body
What are the stages in folliculogenesis?
Primordial follicle
Primary oocyte
Primary follicle
Growing follicle
Antral follicle
Ruptured follicle
Secondary oocyte
Ovulation
Corpus luteum
Degenerating corpus luteum
Summarise the process of oogenesis.
Ovulation = release of mature oocyte (egg) from the ovary
Oocyte is 2n at this stage, in meiotic arrest (metaphase II)
Enters the Fallopian tube
Needs to be fertilised within 24 hours, as it degenerates after this
What are the stages of fertilisation?
Sperm swim towards egg in fallopian tube.
Sperm bind to zona pellucida on outside of egg.
Egg is surrounded by cells of corona radiata.
Sperm produces digestive enzymes to digest their way through the cells and zona pellucida.
One sperm releases its nucleus into the cytoplasm of the egg.
Nucleus expands rapidly in size and converts itself to the male pronucleus (haploid).
Egg completes meiosis- becomes haploid, female pronucleus.
Pronuclei merge.
What are the processes that follow fertilisation?
Meiosis of maternal chromosomes resumes, forming female pronucleus (23 chromatids), and second polar body
Sperm chromosomes decondense to form male pronucleus (23 chromatids)
Chromatids in both pronuclei are duplicated
They align on the mitotic spindle, and are separated into 2 identical ‘daughter’ cells (first cleavage division of the embryo)
