Sex Determination Flashcards
Primary sex traits
anatomy
Secondary sex traits
Features that contribute to reproductive success
Excological sex traits
Traits that allow M/F to inhabit different habitats to lower competition
Role of chromatin (KDM6B) in TSD
Hight temp –> Ca 2+ channels open –> Stat3 ON –| KDM6b –> Female genes
KDM6b removes a methyl group from histone H3K27 which enhacnes DMRT1 transcription
Role of DMRT1 in TSD
DMRT1 is a txn factor for sex determination that is active whe KDM6b is activated.
Turner’s and Kleinfelter’s Syndromes
Turner: XO karyotype - sterile female, no ovaries or eggs
Kleinfelter’s: XXY karyotype - sterile male, few sperm, small testes
1 degree sex determination
Specification of the sex of the gonad, determined by chromosomes
Second degree sex determination
Specification of the bodily phenotype, the internal and external genitalia. Determined by hormones produced by the gonad
Somatic cells of the gonad
From the mesoderm
Forms as a genital ridge - a precursor to the gonads - on the surface of the mesonephos (embryonic kidney)
Provide structural framework and signaling for development of germ cells into sperm or eggs
Germline cells of the gonad
Specialized cells that give rise to gametes
Specified in the posterior of the embryo
Primordial gem cells (PGCs) migrate through the hindgut, multiplying as they migrate.
The fate of the germline cells is determined by the gonadal environment created by the somatic cells.
Bipotential gonad
The early, undifferentiated stage of gonad development in mammals where the gonadal primordium has the capacity to develop into either testis or an ovary
Wollfian Ducts
Male, represent the embryoinic precursors to the male internal reproductive structures
Mullerian Ducts
Female, embryonic precursors to the female internal reproductive structures including oviducts, uterus, and cervix.
How the gonad forms (Male)
- Formation of the genital ridges by somatic cells.
- Migration of PGCs through chemotaxis with SDF1
- Germ cells arrive at the genital ridges and are enveloped by somatic cells
- SRY genes is activated within the somatic cells producing SRY protein.
- SRY activates SOX9
- SOX9 txn factor turns wnt off and initiates the differentiation of Sertoli cells (testis cords).
- Sertoli cells produce anti Mullerian hormone
- Leydig cells (somatic cell) produce testosterone which promotes the differentiation of the Wolffian Ducts
How the gonad forms (female)
- Formation of the genital ridges by somatic cells.
- Migration of PGCs through chemotaxis with SDF1
- Germ cells arrive at the genital ridges and are enveloped by somatic cells
- in the absence of SRY, other transcription factors activate the Wnt signling pathway
- Wnt –> B-cat accumulates which regulates ovary development and promotes the differentiation of somatic cells into granulosa cells
- R-spondin1 enhances wnt signaling for xx pathway
- Granulosa cells and thecal cells for follicles and work together to produce estrogen.
