Quest 4 Flashcards
(41 cards)
1
Q
Tonic and Surge Center
A
- Tonic center (flat line)
- allows basal concentration of GnRH to fetus at all times - Surge Center
- follows basal concentration of GnRH and peaks
2
Q
Puberty
A
- sexual maturation (ability to successfully reproduce)
- need:
1. Gamete production
2. Steroid Hormones
3. Development of Reproductive Tissue - since puberty is a gradual process, it is necessary to have fully functional GnRH neurons
- so, must produce a sufficient amount of GnRH (GnRH prod LH and FSH)
3
Q
Morula
A
- all cells have totipotency
- is cleaved, so you can not tell how many cells (ball of cells)
- will become a blastocyst
4
Q
Path to produce estradiol in males
A
- all steroid hormones begin at cholesterol
1. Cholesterol
2. Progesterone
3. Testosterone
4. Estradiol
5
Q
Sex vs Gender
A
- Sex- chromosomes
2. Gender- you (what you identify as)
6
Q
Reproductive Organ Development in males
A
- Germ cells migrate from yolk sac to genital ridge
- Causes proliferation of connective tissue (mass growth)
- Results in the formation of primitive sex cords
- will eventually become seminiferous tubules(1) in the male - Testis Enlarge and begin to press against the kidneys
- – beg at about 10-15mos gestation - The paramesonephric ducts begin to regress
- Retain the mesonephric tubules and they become the efferent ducts(3)
- Mediastinum(2) forms and is a connection point for the seminiferous tubules
- Development of mesonephric duct
- Mesonephric duct gives rise to the epididymis(4) and ductus deferens(5)
- testosterone supports these - Gubernaculum grows as testis get closer to the scrotum (drags testis deep into scrotum)
- There are forces at work to pull and push down testis through peritoneal layers
- Once testis is through the inguinal ring, the gubernaculum will shrink because the job is complete (50-75% of gestation)
* Gubernaculum depends on testosterone
7
Q
Define Differentiation
A
- the process where a group of unspecialized cells develop into recognizable groups of cells that have a common function
8
Q
3 Secretion Patterns of Hormones
A
- Tonic, Basal
- Pulsatile, Surge
- peaks about every 20 days - Sustained
ex: pregnancy when progesterone remains high
- will see all 3 patterns in females
- will only see tonic, basal pattern in males
9
Q
Surge Center in Males
A
- do not need surge center, so need to get rid of it
- Defeminization of brain(gets rid of surge center)
- need testosterone in order to convert it to estrogen/estradiol which will destroy the surge center
10
Q
Signs of Puberty
A
- Males
- reproductive behavior
- secondary sex characteristics
- first sperm seen in ejaculate
- when large number of sperm seen in ejaculate - Female
- reproductive behavior
- secondary sex characteristics
- first estrous cycle (in heat)
- first ovulation
- when pregnancy paired successfully without deleterious effects
11
Q
Endocrinological Study
A
- performed a common endocrinological study of ablation/replacement
1. Dr. Alfred Jost - studied rabbits
- extracted the uterine horn and took the fetus out of the uterus
- Gonadectomized(castrated) the fetus before it developed into a sex
- the rabbit defaulted to female
2. Natalie Josso - discovered that the rabbit developed female because of the extraction of the testis
12
Q
Allantois sac
A
- connected to yolk sac of embryo
- waste
13
Q
Development Sequence of Organs in male
A
- Seminiferous Tubules
- Mediastinum
- Efferent Ducts
- Epididymis
- Ductus Deferens
14
Q
Mammal Chromosomes and Bird Chromosomes
A
- Mammals
- xy = male
- xx = female - Birds
- zz = male
- zw = female
15
Q
Environments Role in the development of hypothalamic GnRH in the female (or onset of puberty)
A
- stress can delay estrous cycle
- light (day length), in horses longer days activate reproduction, in sheep longer nights(dark) activates reproduction
- Social Environment
1. 5 females and 1 male - will be more reproductively active in presence of male
2. 10 females- estrous cycles can link up
3. 5 females
16
Q
Factors that impact the development of hypothalamic GnRH in the female (or onset of puberty)
A
- Environment
- Plane of Nutrition
- Genetics
17
Q
Surge Center in Females
A
- important 4 females, because allows LH production to increase and ovulation to occur
- (alpha)fetoprotein binds estradiol preventing it from crossing the blood-brain barrier and destroying surge center
18
Q
GnRH as a requirement for Puberty
A
- since puberty is a gradual process, it is necessary to have fully functional GnRH neurons
- so, must produce a sufficient amount of GnRH
- Establish a number of GnRH neurons
- make functional
- limiting factor for the onset of puberty is the number of presynaptic neurons
- make those functional and can assist in making GnRH neurons functional
- Kisspeptin is the gate-keeper for GnRH
19
Q
What stages of the sexual differentiation process occurs during puberty?
A
- Hormones
- Anatomy development of individual
- Psyche
20
Q
(alpha)fetoprotein
A
- in females, it is produced by the liver and yolk sac during gestation, declines greatly after birth
- will no longer prevent estrogen from returning to the brain - Leaves the male brain with only the tonic center
- GnRH, FSH, LH and testosterone are still secreted
21
Q
Reproductive Organ Development in females
A
- Germ cells migrate to the genital ridge
- in mammals ameboid movement
- in birds vascular movement - Proliferation of connective tissue
- tubal formation
- fragmented tubes
- > germ cells are encapsulated one germ cell at a time - Penetrate less deeply
- follicles are in the cortex - Regression of Mesonephric Ducts
- Persistence of Paramesonephric Ducts
- Paramesonephric Ducts
- form oviduct and anterior vagina - Urogenital Sinuses
- forms posterior vagina and vulva
22
Q
Two most important hormones is producing male reproductive tract
A
- Testosterone develops male tract
2. Anti-Mullerian Hormone
23
Q
Blastocyst
A
- formed from a morula that had totipotency
- has 2 cell types
1. Trophectoderm - outer cell Mass
- fetal membrane
2. Inner Cell Mass - all cells have pluripotency
- embryo
- contains 3 germ layers
24
Q
3 Germ Layers
A
- within the Blastocysts germ layers rise from Inner Cell Mass
1. Ectoderm (outer layer) - skin, hair, sweat glands, nervous system
2. Mesoderm (middle layer) - skeletal, circulatory, urinary, muscular, reproductive
3. Endoderm (inner layer) - digestive, endocrine, liver, pancreas, lungs
25
Male and female ducts in reproductive tract development
1. Male
- Wolffian ducts, or mesonephric ducts
2. Female
- Mullerian ducts, or paramesonephric ducts
26
Prepubertal vs Postpubertal conc of GnRH released in males and females
1. Prepubertal
- both male and female tonic center only
2. Post Pubertal
- female has surge and tonic center working
- male only has tonic center
27
Plane of Nutritions Role in the development of hypothalamic GnRH in the female (or onset of puberty)
- optimal size
| - can be too thin, or too fat
28
Why normally can placentas in uterine horn not normally share blood supply?
- because where the placenta touches there are necrotic ends to prevent this
29
Female Reproductive Tract Formation Process
- is the default
1. NO Y chromosome, NO SRY, NO TDF
2. Ovarian development-> NO AMH and mullerian ducts persist
3. No AMH -> NO testosterone-> regression of Wolffian Ducts
4. Mullerian Ducts Persist-> vulva, ovaries, anterior vagina, (everything else)
30
Male Reproductive Tract Formation Process
- Y chromosome is present on the male
1. section of Y chromosome that contains the sex determining region of the Y chromosome (SRY)
2. SRY triggers testis determining factors (TDF)
- testis development begins
- Ducts are directly connected to the gonads
3. Sertoli Cell Differentiation triggers the production of ***Anti-Mullerian Hormone(regresses the mullerian/Paramesonephric ducts, xx)*** and Leydig Cell Differentiation
4. Leydig Cell Differentiation produces Testosterone and Dihydrotestosterone
5. ***Testosterone supports the epididymis, ductus deferens and Mullerian/Wolffian ducts
6. Dihydrotestosterone supports production of accessory sex glands, penis and sheath
31
Genital Ridge
- thickened upper portion of bipotential gonads
32
What stages of the sexual differentiation process occurs during fetal development?
1. Genes
2. Gonads
3. Tracts/Ducts
4. Hormones
33
Three variations of Kidneys in Renal System
1. Pronephros (pro = before, nephros = neuron in kidney)
- giant nephron, nonfunctional
- will eventually regress via apoptosis
* *2. Mesonephros (mesa = middle)
- very important in male tract
- contains bipotential gonads at this state and both xy and xx ducts
- closely associated with the mesonephric/Wolffian ducts(xy)
- Mesonephric ducts drain the urine that the mesonephros produces
- functional
- in fish and amphibians permanent
3. Metanephros (last stage of kidney development)
- fully functional adult kidney
- begins to appear by the first 10-15% of gestation and becomes functional by the first 30-35% of gestation
34
Sexual Differentiation Process
1. Genes code for
2. Gonads that develop and produce the
3. Tracts/Ducts which produce
4. Hormones that affect the development of
5. Anatomy development of the individual
6. Psyche develops last
- 1,2,3,4 occur during fetal development
- 4,5,6 occur during puberty
35
Genetics Role in the development of hypothalamic GnRH in the female (or onset of puberty)
```
DOGS
- large dog (8 mos)
- small dog (4 mos)
CATTLE
- dairy (7-9 mos)
- beef (12-13 mos)
- basindicus (24 mos)
PIGS (6 mos)
- Meishan (3 mos)
```
36
Potency of Cells
- the degree of specialization that the cell has the potential for
37
1. If have no AMH, but has Testosterone
2. If have AMH and has Testosterone
3. If have AMH and no Testosterone
4. If have no AMH and no Testosterone
1. Will have both reproductive tracts
- Mullerian Duct AND Wolffian Duct
2. Male reproductive tract (Wolffian Ducts)
3. Will have neither tract
4. Female reproductive tract (Mullerian Ducts)
38
Potency of Cell Types
1. Totipotency
- cell can develop into ANYTHING
2. Pluripotency
- cell can develop into ALMOST anything, EXCEPT PLACENTA
- pluripotent cells will become multipotent
3. Multipotency
- can develop into SOME things
- progenitor cell
4. Oligopotency
- can develop into FEW things based on progenitor cells
5. Unipotency
- can develop into ONE thing
39
Freemartin
- in cattle, co-twins
- male reproductive tract is fine
- female reproductive tract is sterile (no Mullerian Tubes bc males AMH)
- hormones affect because they share a uterus
- anastomosis (placenta vascularity joins together and hormones affect female tract)
40
Feedback Loops
1. Female
- Positive Feedback
- too little estrogen
- decrease sensitivity of GnRH neurons to estrogen
- gradually inc the amount of estrogen to have an affect and activate the surge center
2. Male
- Negative Feedback
- testosterone, some estrogen
- decrease sensitivity of GnRH neurons to testosterone
41
How do germ cells migrate from the yolk sac?
- germ cells migrate from the yolk sac to the genital ridge (thickened upper portion of bipotential gonads)
- how the germ cells populate the gonads is based on sex determination!
