12. Sex determination and differentiation Flashcards
There are only 2 anterior pit hormones that are controlled by both releasing and inhibiting hormones. What are they?
prolactin and growth hormone
What are the 3 hormones needed for breast milk production?
PRH, PIH (DA), Prolactin
Within the breast tissue also known as the _________ gland there are 15 to 20 milk lobes. Each lobe is subdivided into _______, which contain _______ which secrete milk
mammary, lobules, alveoli
Put the following in order for where secreted milk travels
a) mammary ducts
b) lactiferous ducts
c) alveoli
d) secondary tubules
e) nipple
c -> d -> a -> b -> e
Where is breast milk produced?
the alveoli
T or F - during pregnancy the breast tissue grows and milk is produced
F - milk production is prevented at this time
What prevents the milk production during pregnancy?
the presence of the placenta causing INC secretion of estrogen which causes a negative feedback activating the PIH which DEC prolactin secretion
What are the two major roles of the placenta during pregnancy?
- INC estrogen which DEC prolactin preventing production of milk
- INC estrogen and progesterone INC growth and development of the breast tissue
We all know that the placenta prevents milk production during pregnancy but why does this stop after birth?
birth causes the removal of the placenta causing a DEC in estrogen release. This in turn INC the secretion of prolactin
Describe the roles of the following hormones wrt breast milk
a) prolactin - 2
b) oxytocin - 2
a) Its from the anterior pit and only controls milk production
b) its from the posterior pit and only controls milk secretion
What triggers the release of oxytocin?
baby related stimulus such as visual/auditory cues or even thinking about them
Draw a flow chart of the stimulus and response wrt breast milk using the following terms; posterior pit, anterior pit, hypothalamus, suckling, milk ejection, prolactin, oxytocin, milk production , sensory input (make sure to indicate which ones are involved in the stimulus vs the response)
T or F - since oxytocin is used to help the release of breast milk it is only produced in females
F - it is produced in both males and females due to it having multiple fxns
We know that oxytocin is used to help the release of breast milk but what is it mostly known as? Why?
the trust hormone as it promotes social behaviour
What is the SRY gene?
a) sex determining region of the Y = a region on the Y chromosome that is important for male determination
What develops into a gonad during the development of sex differentiation?
bipotential primordium
Describe the 4 steps involved in the female sex differentiation using the following steps; SRY protein, bipotential primordium, ovaries, uterus, vagina, fallopian tube, testosterone, Wolffian duct Mullerian duct, Mullerian inhibition factor (MIF), Sertoli cells.
- lack of SRY protein causes the bipotential primordium to develop into the ovaries
- the lack of testosterone causes the Wolffian duct to degenerate
- Due to the absence of Sertoli cells no MIF is produced allowing for the development of the Mullerian duct
- the Mullerian duct becomes the fallopian tube, uterus, and vagina
Describe the 4 steps involved in the male sex differentiation using the following steps; SRY protein, bipotential primordium, testes, seminal vesicles, vas deferens, epididymis , testosterone, Wolffian duct Mullerian duct, Mullerian inhibition factor (MIF), Sertoli cells.
- presence of SRY protein causes the bipotential primordium to develop into the testes
- the presence of testosterone causes the development of the Wolffian duct
- Due to the presence of Sertoli cells MIF is produced causing the degeneration of Mullerian duct
- the Wolffian duct becomes the seminal vesicles, vas deferens (carries sperm out of testes) , and epididymis
a) What is this an image of
b) How old is the fetus at this time?
c) what sex is the fetus at this time?
a) bipotential primordium
b) 6 weeks
c) unknown
a) All somatic cells have _____ chromosomes making them ______, while all germ cells have ___ chromosomes making them ______
b) Genetic females are genetically ____ while males are ___. Meaning that the _____ determine the sex of the baby
a) 46, diploid, 23, haploid
b) XX, XY, father
a) What does TDF stand for?
b) What is it also known as?
a) testis determining factor
b) SRY
What is happening in this image? - 3
- Transfer of SRY gene to the X chromosome
- the offspring that got the recombined X chromosome despite genetically being XX appears male due to the presence of the SRY gene
- the offspring that got the recombined Y chromosome despite genetically being XY appears due to the absence of SRY gene
T of F - SRY is the ultimate ‘maleness gene’
F - while it plays a major role in sex determination it is not the only factor
Aside from SRY what else plays a role in sex determination? explain - 4
- INSR = insulin receptor
- IGF1R = insulin-like growth factor 1 receptor
- INSSR = insulin receptor-related receptors
mutations to all three of these can cause a female phenotype despite the presence of both SRY and the indiv being genetically XY
