Intro and embryo sex differentiation (Dr. Seg) Flashcards
List reproductive hormones produced by the placenta
- Progesterone
- Estradiol
- hCG
- eCG
- Oxytocin
- PGF2a
What are totipotent cells?
- Can give rise to any tissue in the body
- Begins at the 2 to 16-cell stage
What happens during the morula stage of embryo development?
- Cells differentiate into 2 groups: Inner cell mass and Trophoblast
- Inner cell mass form the embryo
- Trophoblast develops the chorion (external portion of placenta)
What is the function of the trophoblast?
- Develops into the chorion (external portion of the placenta)
- Pumps Na+ into intracellular space, embryo fills with “water” which forms blastocele
The anterior and posterior pituitary gland is considered part of the ______
A. Endoderm
B. Mesoderm
C. Ectoderm
C. Ectoderm
_________ is the external embryonic tissue that gives rise to the placenta
Trophoblast
What is the innermost layer that surrounds the developing embryo?
Amnion
What is the outermost layer surrounding the developing embryo, that lies against the uterus?
Chorion
What is a clinical implication of the schistosomus reflex?
- Mother will have dystocia
- Rare but fatal
- Occurs more commonly in ruminants
What is the schistosomus reflex?
- Abnormality in organogenesis where vital organs develop OUTSIDE of the embryo (before skin)
__________ is when there are extra or missing chromosomes
Aneuploidy
Gonadal sex is determined by?
SRY gene and testis determining factor hormone
What is the pathway of sex determination in males?
Presence of SRY gene → secretes testis determining factor (TDF) → forms testis → Sertoli cells secrete AMH → paramesonephric duct degenerates → AMH causes leydig cells to differentiate → Testosterone produced to develop male duct system → dihydrotestosterone produced to develop phenotype (penis, scrotum, accessory sex glands) → its a boy!!
What is the pathway of sex determination in females?
Absence of SRY gene (No testis determining factor) → forms ovary → paramesonephric duct/ Mullerian hormone continues to form (due to no AMH) → Develops uterus, oviducts, cervix and cranial vagina to develop → its a girl!!
What is chimera?
- 2 different zygotes in a single embryo
- Ex: hermaphrodite
What is mosaic?
- 2 different cell lines originating from 1 zygote
- Ex: Turners syndrome
What is the function of AMH in males?
- Develops Leydig cells which then produce testosterone to form the male duct system
What is the function of leydig cells?
- Triggered by AMH in male sex differentiation
- Produces testosterone to form the male duct system
What is the pathophys behind males having only a tonic center?
- Testosterone crosses the BBB in males THEN converts into estradiol to defeminize and and destroy the surge center
Estradiol is bound to alpha fetal protein in FEMALES which CAN’T cross the BBB (requires testosterone)
What happens with Freemartinism?
- Female and Male twins
- AMH and testosterone from male transfers to the female placenta
- Female has normal external features but abnormal internal repro tract (small ovaries, small uterus)
What are the phases of testicular descent?
- Transabdominal phase
- Inguinoscrotal phase
What occurs during the transabdominal phase of testicular descent?
- Testosterone degenerates the CSL
- Leydig cells produce Insulin like hormone 3 (INSL3) which controls gubernacular development and thickening
What occurs during the inguinoscrotal phase of testicular descent?
- Thickened gubernaculum and abdominal pressure causes dilation of the inguinal canal for testis to descend
