Environmental Impacts on Sexual Development Flashcards
What did industrial effluents do to fish and what does this imply?
Male fish upregulated vitellogenin which is an egg component normally only found in the female. It implied estrogens in industrial effluent.
How was this similar in aligators?
Genital abnormalities in neonatal alligators in florida everglades. (Places close to industrial effluents)
Why are alligators not a good model for genital malformations in humans?
Their sex determination is temperature dependent whereas in humans it is dependent on hormones dependent on SRY - so confounding effects??
What are the clinical trends in:
a) birth defects
b) sperm
c) testicular cancer
a) Increasing cryptorchidism and hypospadias
b) Increased incidence of Decreased sperm counts (oligozoospermia). This is thought to be linked to decreased fetal sertoli cells.
c) Decreased sperm counts are a risk factor for testicular cancer and vica versa. Increased incidence of this reflects abnormal development of fetal germ cells. It can also reflect testicular dysgenesis.
How are sertoli cells involved in spermatogenesis?
They provide graded microenvironments for the sperm. Their number determines the spermatogenic capacity of the testes. Estrogens or environmental estrogen mimics are toxic to sertoli cells.
What are the different sources of environmental estrogens?
The pill Phytoestrogens (soy) Polychlorobisphenols (PCB) phthalates - both the above are plasticizers) anionic detergents
What is testicular dysgenesis?
Disorder of testes histology due to abnormal sertoli/leydig cell development and therefore poorly formed seminiferous tubules.
What is its link to testicular cancer?
It is commonly seen in the contralateral testis of men with unilateral testicular cancer.
What are the main characteristics of it?
Immature/lack of sertoli cells
Foci of leydig cell hyperplasia.
What was the effect of dibutyl phthalate on the pups of treated pregnant rats?
Only 2/10 fertile
6/10 hypospadias
all were cryptorchid.
How was testicular descent related to testicular weight?
Those that descended displayed catch up growth.
Why would there be leydig cell hyperplasia?
Reduced testosterone production would lead to high LH levels (as no negative feedback) so Leydig cells would hyperplasia to catch up.
How did DBP affect the seminiferous tubules?
Sertoli cell only tubule with no lumen - very little spermatogenesis.
Why would incomplete formation of seminiferous tubules be very bad?
There would be a lack of blood-testes barrier leading to inflammation.
Summarise the primary defects in TDS.
Incomplete sertoli cells formation
Lack of germ cells but inclusion of Leydig cells in STs.
Decreased leydig cell testosterone output and subsequent leydig cell hyperplasia, cryptorchidism and/or hypospadias.
How did sewage sludge affect lambs born to grazing sheep?
It had an adverse impact on ovarian development, hypothalamic development
- Decreased Kiss-1 mRNA
- Decreased hypothalamic kisspeptin
