Reproduction Flashcards
What is the meaning of viviparous?
Live young which have developed inside the body of a parent
What does the hypothalamic pituitary gonodal axis drive?
sexuality and performance
What is the meaning of GnRH?
Gonadotropin-releasing hormone
In Females the release of GnRH stimulates the growth and development of what?
The uterus and the mammary glands
When is reproduction risky for males?
When stags rutt
When is reproduction risky for females?
Childbirth - 1 in 16 births in Sub-saharan Africa results in the death of the mother (1 in 2800 in developed countries)
What are the functions of male reproduction?
To produce lots of sperm continuously and to deliver the sperm to the female
What are the functions of female reproduction?
Production of the ova
Ovulation
Reception of sperm
Transport of sperm and ova for fertilisation
At what phase of development to the ova arrest during fetal development?
Late prophase /diplotene stage of meiosis
How many germ line cells are present for a female at birth? (considering the development of the ova)
7 million
How many oocytes are present in the ovaries at puberty?
400,000
How many oocytes are fertile in the life time of a woman?
400-500
By which hormone is the placenta maintained? And where is this hormone released from?
Progesterone released from the Corpus Lutea / Placenta
What does the term Parturation mean?
The action of giving birth to young (childbirth)
What is colostrum?
The first substance released from the mammary glands which contains antibodies to protect the newborn from disease
What is lactogenesis?
The onset of milk production from the mammary glands around the time of parturation
By which hormones is lactogenesis maintained?
Prolactin (and growth hormone in cattle)
Which hormone stimulates milk ejaculation?
Oxytocin
How is gonadal sex determined?
Gonadal sex is determined on the basis of the gonadal tissue (ovarian/ testicular) present. It is determined by genetic sex.
What determines genetic sex?
The sex chromosomes (XX- female) (XY- male)
What is a gonad?
An organ which produces gametes (testes or ovaries)
What does hCG stand for and when is it produced?
Human Chronic Gonadotrophin is produced by the embryo upon plantation in the wall of the uterus (it is detected by some pregnancy tests)
Which reproductive organs does the mullerian duct develop into?
Female reproductive organs
Which reproductive organs does the Wolffian duct develop into?
Male reproductive organs
What does SRY stand for?
Sex determining region Y (found on the Y chromosome)
What the transcription of the SRY gene cause?
Differentiation of Sertoli cells (formation of male reproductive organs)
Where are sertoli cells found and what process are they involved in?
They are found in the seminiferous tubule and are involved in spermogenesis
What does the differentiation of the sertoli cells cause?
The activation of the SOX9 gene, the protein transcribed from this gene helps to inhibit the formation of the female reproductive system
What causes Mullerian duct regression in males?
An increase in anti-mullerian hormone (AMH) and a decrease in aromatase (also called oestrogen synthase - involved in the biosynthesis of oestrogen)
What happens when there is no SRY gene? e.g. in females
There is a decrease in the transcription of SOX9
A decrease in SOX9 causes what?
An increase in ovary development factors, a decrease in anti- mullerian hormone (AMH) and an increase in aromatase
Is the undifferentiated brain male or female?
Female
Androgens control which male characteristics?
Masculinity (mounting and sexual behaviour), defeminisation (curvature of the spine, sexual receptivity and a surge in LH are all characters associated with females)
When is genome imprinting?
When one allele from one parent is silenced so only the allele from the other parent is expressed, can be caused by oestrogen in males (females have oestrogen binding proteins to prevent this)
When does puberty occur in females?
When the release of LH increases in both frequency and amplitude, and when there is a reduce response to negative feedback from oestradiol
What does LH stand for?
Luteinizing hormone
What is oestradiol?
A major oestrogen produced in the ovaries
In males is testosterone produce cyclically or constantly?
Constantly
What is the difference between the oestrus cycle and the menstral cycle?
In the oestrus cycle the endometrium (uterine lining) is reabsorbed but in the menstrual cycle it is shed. Another difference is that animals with an oestrus cycle are only sexually active when they are in oestrus (in heat) compared to menstrual cycle animals which can be sexually active at all times of their cycle.
What is the follicular phase?
The phase of the oestrus or menstrual cycle in which the follicles in the ovary mature
What process occurs whilst a follicle is maturing an ovary before ovulation?
The Corpus Luteum is formed
The primary follicle contains a primary oocyte arrested at which meiotic division?
The first
Which cell layer develops in the primary and secondary follicles?
A single layer of granulosa cells
What stimulates ovulation?
A surge in LH
Which events are caused by a surge in LH?
Follicle stops producing oestrogen, meiosis restarts in the oocyte, paracrines PGE2 and PGF2 alpha are produced, follicular cells differentiate into luteal cells
What is the luteal phase?
The late phase of the menstraul cycle or the early stage of the estrous cycle
What is the first stage of the luteal phase?
The formation of the Corpus Luteum
Which hormone maintains the Corpus Luteum?
Progesterone
During the luteal phase which hormone stimulates the uterus to secrete the paracrine PGF2 alpha?
Oxytocin
In the event that there has been no implantation of an egg in the uterus, the secretion of PGF2 alpha stimulated by oxytocin initiates what?
Luteolysis (the degradation of the corpus luteum), a decrease in progesterone is also needed
During the luteal phase which hormone increases the oestrogen receptors in the uterus?
Progesterone
In pregnancy the production of luteolytic proteins does what?
Decreases oxytocin receptors, a decrease in PGF2 alpha synthesis and a prevention of luteolysis
Which hormone is required through the whole of pregnancy?
Progesterone
Progesterone is released from the corpus leutum in the ovaries but in addition it can be released from where?
The placenta
Which hormone, which is increasing produced during pregnancy suppresses gonadotrophin releasing hormone and gonadotrophin hormone production?
Oestrogen
High levels of oestrogen do what in a pregnant female?
Prepare the cervix and uterus for parturation
Which hormone released by the placenta is involved in aiding fetal lung maturation, increasing oestrogen production, decreasing progesterone production and increasing PGF2 alpha release?
Corticotropin-releasing hormone
High oestrogen levels stimulated what?
Increased oxytocin receptors in the smooth muscle tissue of the womb (myometrium)
Pressure of the fetus against the cervix, high oxytocin and PGF2 alpha all contribute to what?
Uterine contractions
